Combined Effects of the North Atlantic Oscillation and the Arctic Oscillation on Sea Surface Temperature in the Alborán Sea

We explored the possible effects of the North Atlantic Oscillation (NAO) and Arctic Oscillation (AO) on interannual sea surface temperature (SST) variations in the Alborán Sea, both separately and combined. The probability of observing mean annual SST values higher than average was related to NAO and AO values of the previous year. The effect of NAO on SST was negative, while that of AO was positive. The pure effects of NAO and AO on SST are obscuring each other, due to the positive correlation between them. When decomposing SST, NAO and AO in seasonal values, we found that variation in mean annual SST and mean winter SST was significantly related to the mean autumn NAO of the previous year, while mean summer SST was related to mean autumn AO of the previous year. The one year delay in the effect of the NAO and AO on the SST could be partially related to the amount of accumulated snow, as we found a significant correlation between the total snow in the North Alborán watershed for a year with the annual average SST of the subsequent year. A positive AO implies a colder atmosphere in the Polar Regions, which could favour occasional cold waves over the Iberian Peninsula which, when coupled with precipitations favoured by a negative NAO, may result in snow precipitation. This snow may be accumulated in the high peaks and melt down in spring-summer of the following year, which consequently increases the runoff of freshwater to the sea, which in turn causes a diminution of sea surface salinity and density, and blocks the local upwelling of colder water, resulting in a higher SST.     

Cyclic Negative Feedback Systems: What is the Chance of Oscillation?

Many biological oscillators have a cyclic structure consisting of negative feedback loops. In this paper, we analyze the impact that the addition of a positive or a negative self-feedback loop has on the oscillatory behavior of the three negative feedback oscillators proposed by Tsai et al. (Science 231:126–129, 2008) where, in contrast with numerous oscillator models, the interactions between elements occur via the modulation of the degradation rates. Through analytical and computational studies we show that an additional self-feedback affects the oscillatory behavior. In the high-cooperativity limit, i.e., for large Hill coefficients, we derive exact analytical conditions for oscillations and show that the relative location between the dissociation constants of the Hill functions and the ratio of kinetic parameters determines the possibility of oscillatory activities. We compute analytically the probability of oscillations for the three models and show that the smallest domain of periodic behavior is obtained for the negative-plus-negative feedback system whereas the additional positive self-feedback loop does not modify significantly the chance to oscillate. We numerically investigate to what extent the properties obtained in the sharp situation applied in the smooth case. Results suggest that a switch-like coupling behavior, a time-scale separation, and a repressilator-type architecture with an even number of elements facilitate the emergence of sustained oscillations in biological systems. An additional positive self-feedback loop produces robustness and adaptability whereas an additional negative self-feedback loop reduces the chance to oscillate.     

Desflurane Preconditioning Induces Oscillation of NF-κB in Human Umbilical Vein Endothelial Cells

Background

Nuclear factor kappa B (NF-κB) has been implicated in anesthetic preconditioning (APC) induced protection against anoxia and reoxygenation (A/R) injury. The authors hypothesized that desflurane preconditioning would induce NF-κB oscillation and prevent endothelial cells apoptosis.

Methods

A human umbilical vein endothelial cells (HUVECs) A/R injury model was used. A 30 minute desflurane treatment was initiated before anoxia. NF-κB inhibitor BAY11-7082 was administered in some experiments before desflurane preconditioning. Cells apoptosis was analyzed by flow cytometry using annexin V–fluorescein isothiocyanate staining and cell viability was evaluated by modified tertrozalium salt (MTT) assay. The cellular superoxide dismutases (SOD) activitiy were tested by water-soluble tetrazolium salt (WST-1) assay. NF-κB p65 subunit nuclear translocation was detected by immunofluorescence staining. Expression of inhibitor of NF-κB-α (IκBα), NF-κB p65 and cellular inhibitor of apoptosis 1 (c-IAP1), B-cell leukemia/lymphoma 2 (Bcl-2), cysteine containing aspartate specific protease 3 (caspases-3) and second mitochondrial-derived activator of caspase (SMAC/DIABLO) were determined by western blot.

Results

Desflurane preconditioning caused phosphorylation and nuclear translocation of NF-κB before anoxia, on the contrary, induced the synthesis of IκBα and inhibition of NF-κB after reoxygenation. Desflurane preconditioning up-regulated the expression of c-IAP1 and Bcl-2, blocked the cleavage of caspase-3 and reduced SMAC release, and decreased the cell death of HUVECs after A/R. The protective effect was abolished by BAY11-7082 administered before desflurane.

Conclusions

The results demonstrated that desflurane activated NF-κB during the preconditioning period and inhibited excessive activation of NF-κB in reperfusion. And the oscillation of NF-κB induced by desflurane preconditioning finally up-regulated antiapoptotic proteins expression and protected endothelial cells against A/R.     

Review article. Studying climate effects on ecology through the use of climate indices: the North Atlantic Oscillation, El Niño Southern Oscillation and beyond

Whereas the El Niño Southern Oscillation (ENSO) affects weather and climate variability worldwide, the North Atlantic Oscillation (NAO) represents the dominant climate pattern in the North Atlantic region. Both climate systems have been demonstrated to considerably influence ecological processes. Several other large-scale climate patterns also exist. Although less well known outside the field of climatology, these patterns are also likely to be of ecological interest. We provide an overview of these climate patterns within the context of the ecological effects of climate variability. The application of climate indices by definition reduces complex space and time variability into simple measures, ''packages of weather''. The disadvantages of using global climate indices are all related to the fact that another level of problems are added to the ecology-climate interface, namely the link between global climate indices and local climate. We identify issues related to: (i) spatial variation; (ii) seasonality; (iii) non-stationarity; (iv) nonlinearity; and (v) lack of correlation in the relationship between global and local climate. The main advantages of using global climate indices are: (i) biological effects may be related more strongly to global indices than to any single local climate variable; (ii) it helps to avoid problems of model selection; (iii) it opens the possibility for ecologists to make predictions; and (iv) they are typically readily available on Internet.     

Stable isotopic signature of El Niño-Southern Oscillation events in eastern tropical Pacific reef corals

In this study we measured stable oxygen and carbon isotope ratios in the skeletons of massive reef-building corals (Porites lobata and Pavona gigantea) at four widespread locations in the tropical eastern Pacific, each with a unique marine climate. Annual variation in sea surface temperature (SST) varied from 5–7°C at upwelling sites (Gulf of Panamá and Galápagos Islands) to 2–3°C where upwelling was absent [Caño Isand (Costa Rica) and Gulf of Chiriquí (Panamá)]. Annual range in salinity was high in the gulfs of Panamá and Chiriquí (up to 15) and low at Cãno Island and Galápagos (2–3). We characterize the isotopic signatures of recent (15–40 y long records) El Niño/Southern Oscillation (ENSO) events, particularly the very severe 1982–1983 event. Subannual sampling at 1–2 month resolution reveals that the ¹⁸O signal at Caño Island records strong to very strong ENSOs. In the Gulf of Chiriquí, this signal is governed mainly (80%) by salinity and thus is a weak recorder of ENSO events: only the 1951–1952, 1957–1958 and 1972–1973 events appear as significant ¹⁸O anomalies over the period 1940–1984. In the Gulf of Panamá, high variation in both SST and salinity contribute to the ¹⁸O signal. ENSO events at this site are poorly recorded, probably due to ameliorating effects of cool upwelled water during the early stage of the ENSO event. The ¹⁸O record in Galápagos, however, shows a strong correlation with SST and accurately records all but the most severe 1982–1983 ENSO event. Thus, ENSOs are most clearly recorded at sites where salinity variation is minimal. At Caño only strong ENSOs are recorded while mild to strong events appear in the Galápagos record. Nowhere did the ¹⁸O signal accurately record the full range of temperatures that occurred during the 1982–1983 ENSO; however, a stress band on the coral skeleton was evident at all sites. By comparing the ¹⁸O records and skeletal features across sites it may be possible to identify the occurrence of strong to very severe ENSOs prior to instrumental records. The relationship between ¹⁸O and ¹³C was examined and found to be significantly positive and in phase (i.e., either depleted or enriched at the same time) at three of the four sites studied. Weak correlations at some sites may be explained by high variability in water column clarity leading to depleted ¹³C when waters are cool and surface isolation high.     

Early-season warning of soybean rust regional epidemics using El Niño Southern/Oscillation information

Soybean rust (SBR) is a disease of significant impact to Brazilian soybean production. Twenty-four locations in a major growing region in southern Brazil, where long-term (30 years) weather information was available, were selected to estimate the risk of SBR epidemics and identify potential predictors derived from El Niño 3.4 region. A rainfall-based model was used to predict SBR severity in an “epidemic development window” (the months of February and March for the studied region) in the time series. Twenty-eight daily simulations for each year-location (n = 720) were performed considering each day after 31 January as a hypothetical detection date (HDD) to estimate a severity index (SBRindex). The mean SBRindex in a single year was defined as the ‘growing season severity index’ (GSSI) for that year. A probabilistic risk assessment related GSSI and sea surface temperatures (SST) at the El Niño 3.4. region (here categorized as warm, cold or neutral phase) in October–November–December (OND) of the same growing season. Overall, the median GSSI across location-years was 34.5%. The risk of GSSI exceeding 60% was generally low and ranged from 0 to 20 percentage points, with the higher values found in the northern regions of the state when compared to the central-western. During a warm OND-SST phase, the probability of GSSI exceeding its overall mean (locations pooled) increased significantly by around 25 percentage points compared to neutral and cold SST phases, especially over the central western region. This study demonstrates the potential to use El Niño/Southern Oscillation information to anticipate the risk of SBR epidemics up to 1 month in advance at a regional scale.     

Angular Oscillation of Solid Scatterers in Response to Progressive Planar Acoustic Waves: Do Fish Otoliths Rock?

Fish can sense a wide variety of sounds by means of the otolith organs of the inner ear. Among the incompletely understood components of this process are the patterns of movement of the otoliths vis-à-vis fish head or whole-body movement. How complex are the motions? How does the otolith organ respond to sounds from different directions and frequencies? In the present work we examine the responses of a dense rigid scatterer (representing the otolith) suspended in an acoustic fluid to low-frequency planar progressive acoustic waves. A simple mechanical model, which predicts both translational and angular oscillation, is formulated. The responses of simple shapes (sphere and hemisphere) are analyzed with an acoustic finite element model. The hemispherical scatterer is found to oscillate both in the direction of the propagation of the progressive waves and also in the plane of the wavefront as a result of angular motion. The models predict that this characteristic will be shared by other irregularly-shaped scatterers, including fish otoliths, which could provide the fish hearing mechanisms with an additional component of oscillation and therefore one more source of acoustical cues.     

Tolerance of Sponge Assemblages to Temperature Anomalies: Resilience and Proliferation of Sponges following the 1997–8 El-Ni?o Southern Oscillation

Coral reefs across the world are under threat from a range of stressors, and while there has been considerable focus on the impacts of these stressors on corals, far less is known about their effect on other reef organisms. The 1997–8 El-Niño Southern Oscillation (ENSO) had notable and severe impacts on coral reefs worldwide, but not all reef organisms were negatively impacted by this large-scale event. Here we describe how the sponge fauna at Bahia, Brazil was influenced by the 1997–8 ENSO event. Sponge assemblages from three contrasting reef habitats (reef tops, walls and shallow banks) at four sites were assessed annually from 1995 to 2011. The within-habitat sponge diversity did not vary significantly across the study period; however, there was a significant increase in density in all habitats. Multivariate analyses revealed no significant difference in sponge assemblage composition (ANOSIM) between pre- and post-ENSO years for any of the habitats, suggesting that neither the 1997–8 nor any subsequent smaller ENSO events have had any measurable impact on the reef sponge assemblage. Importantly, this is in marked contrast to the results previously reported for a suite of other taxa (including corals, echinoderms, bryozoans, and ascidians), which all suffered mass mortalities as a result of the ENSO event. Our results suggest that of all reef taxa, sponges have the potential to be resilient to large-scale thermal stress events and we hypothesize that sponges might be less affected by projected increases in sea surface temperature compared to other major groups of reef organisms.     

Inhibition of Noncanonical Ca2+ Oscillation/Calcineurin/GSK-3β Pathway Contributes to Anti-Inflammatory Effect of Sigma-1 Receptor Activation

Neurochemical Research - Further understanding the mechanism for microglia activation is necessary for developing novel anti-inflammatory strategies. Our previous study found that the activation of...     

Coral survivors of the 1982–83 El Niño-Southern Oscillation,Galápagos Islands,Ecuador

Reef Sites

Coral survivors of the 1982–83 El Niño-Southern Oscillation, Galápagos Islands, Ecuador     

Surface Plasmon Polariton Mach–Zehnder Interferometer and Oscillation Fringes

We present a quantitative experimental analysis of a surface plasmon polariton (SPP) interferometer relying on elliptical Bragg mirrors. By using a leakage radiation microscope, we observe oscillation fringes with unit visibility at the two interferometer exits. We study the properties of the SPP beam splitter and determine experimentally both the norm and phase of the SPP reflection and transmission coefficients.     

β Oscillation during Slow Wave Sleep and Rapid Eye Movement Sleep in the Electroencephalogram of a Transgenic Mouse Model of Huntington’s Disease

Study objectives

To search for early abnormalities in electroencephalogram (EEG) during sleep which may precede motor symptoms in a transgenic mouse model of hereditary neurodegenerative Huntington’s disease (HD).

Design

In the R6/1 transgenic mouse model of HD, rhythmic brain activity in EEG recordings was monitored longitudinally and across vigilance states through the onset and progression of disease.

Measurements and results

Mice with chronic electrode implants were recorded monthly over wake-sleep cycles (4 hours), beginning at 9–11 weeks (presymptomatic period) through 6–7 months (symptomatic period). Recording data revealed a unique β rhythm (20–35 Hz), present only in R6/1 transgenic mice, which evolves in close parallel with the disease. In addition, there was an unusual relationship between this β oscillation and vigilance states: while nearly absent during the active waking state, the β oscillation appeared with drowsiness and during slow wave sleep (SWS) and, interestingly, strengthened rather than dissipating when the brain returned to an activated state during rapid eye movement (REM) sleep.

Conclusions

In addition to providing a new in vivo biomarker and insight into Huntington''s disease pathophysiology, this serendipitous observation opens a window onto the rarely explored neurophysiology of the cortico-basal ganglia circuit during SWS and REM sleep.     

Non-stationary influence of El Ni?o-Southern Oscillation and winter temperature on oak latewood growth in NW Iberian Peninsula

The properties of El Ni?o-Southern Oscillation (ENSO), such as period, amplitude, and teleconnection strength to extratropical regions, have changed since the mid-1970s. ENSO affects the regional climatic regime in SW Europe, thus tree performance in the Iberian Peninsula could be affected by recent ENSO dynamics. We established four Quercus robur chronologies of earlywood and latewood widths in the NW Iberian Peninsula. The relationship between tree growth and the Southern Oscillation Index (SOI), the atmospheric expression of ENSO, showed that only latewood growth was correlated negatively with the SOI of the previous summer-autumn-winter. This relationship was non-stationary, with significant correlations only during the period 1952-1980; and also non-linear, with enhanced latewood growth only in La Ni?a years, i.e. years with a negative SOI index for the previous autumn. Non-linear relationship between latewood and SOI indicates an asymmetric influence of ENSO on tree performance, biassed towards negative SOI phases. During La Ni?a years, climate in the study area was warmer and wetter than during positive years, but only for 1952-1980. Winter temperatures became the most limiting factor for latewood growth since 1980, when mean regional temperatures increased by 1°C in comparison to previous periods. As a result, higher winter respiration rates, and the extension of the growing season, would probably cause an additional consumption of stored carbohydrates. The influence of ENSO and winter temperatures proved to be of great importance for tree growth, even at lower altitudes and under mild Atlantic climate in the NW Iberian Peninsula.     

Short-Term Effect of El Ni?o-Southern Oscillation on Pediatric Hand,Foot and Mouth Disease in Shenzhen,China

Hand, foot and mouth disease (HFMD) was an emerging viral infectious disease in recent years in Shenzhen. The underlying risk factors have not yet been systematically examined. This study analyzed the short-term effect of El Niño-Southern Oscillation on pediatric HFMD in Shenzhen, China. Daily count of HFMD among children aged below 15 years old, Southern Oscillation Index (SOI), and weather variables were collected to construct the time series. A distributed lag non-linear model was applied to investigate the effect of daily SOI on pediatric HFMD occurrence during 2008–2010. We observed an acute effect of SOI variation on HFMD occurrence. The extremely high SOI (SOI = 45, with 0 as reference) was associated with increased HFMD, with the relative risk (RR) being 1.66 (95% Confidence Interval [CI]: 1.34–2.04). Further analyses of the association between HFMD and daily mean temperature and relative humidity supported the correlation between pediatric HFMD and SOI. Meteorological factors might be important predictors of pediatric HFMD occurrence in Shenzhen.     

The El Niño / Southern Oscillation and Australian vegetation

The El Niño-Southern Oscillation (ENSO) phenomenon has a marked effect on Australia's rainfall. The tendency for major Australian droughts to coincide with ENSO “events” (i.e. anomalously warm sea surface temperatures in the east equatorial Pacific), and for extensive wet periods to accompany “anti-ENSO” events, is well documented. Also well-known is the partial predictability of Australian rainfall anomalies provided by ENSO. Some other ENSO-related characteristics of interannual fluctuations of Australian rainfall are lesswidely recognised, viz:

- rainfall variability is very large

- droughts and wet periods have time scales of about one year

- they exhibit very large (continental) spatial scales

- they tend to be phase-locked with the annual cycle

- they are often followed/preceded by the opposite rainfall anomaly.

The character of Australian rainfall fluctuations is thus very different from that of areas where the influence of ENSO is weak, Europe for instance. Rainfall in some other areas, notably southern Africa and India and parts of the Americas, is also strongly affected by ENSO and shares some of the above characteristics. The relevance of these ENSO-related characteristics of Australian rainfall to its vegetation will be discussed. Australian native vegetation is adapted to these characteristics, especially in the semi-arid inland where ENSO's influence is strong. Most introduced plants are not adapted to ENSO and this has sometimes complicated their use here. The combination of ENSO-related rainfall fluctuations and European land-use strategies has resulted in some very rapid, unpredicted and undesirable changes in vegetation in the past two centuries. It has also increased the risk of soil erosion. Recognition of the real character of Australian rainfall fluctuations may help avoid further degradation of soil and vegetation.     

Fast Pseudo-Periodic Oscillation in the Rat Brain Voltage-gated Sodium Channel α Subunit

In the work reported here, we have investigated the changes in the activation and fast inactivation properties of the rat brain voltage-gated sodium channel (rNa_v 1.2a) α subunit, expressed heterologously in the Chinese Hamster Ovary (CHO) cells, by short depolarizing prepulses (10 – 1000 ms). The time constant of recovery from fast inactivation (τ_fast) and steady-state parameters for activation and inactivation varied in a pseudo-oscillatory fashion with the duration and amplitude of a sustained prepulse. A consistent oscillation was observed in most of the steady-state and non-inactivating current parameters with a time period close to 225 ms, although a faster oscillation of time period 125 ms was observed in the τ_fast. The studies on the non-inactivating current and steady-state activation indicate that the phase of oscillation varies from cell to cell. Co-expression of the β1 subunit with the α subunit channel suppressed the oscillation in the charge movement per single channel and free energy of steady-state inactivation, although the oscillation in the half steady-state inactivation potential remained unaltered. Incidentally, the frequencies of oscillation in the sodium channel parameters (4–8 Hz) correspond to the theta component of network oscillation. This fast pseudo-oscillatory mechanism, together with the slow pseudo-oscillatory mechanism found in these channels earlier, may contribute to the oscillations in the firing properties observed in various neuronal subtypes and many pathological conditions.     

Altered Oscillation and Synchronization of Default-Mode Network Activity in Mild Alzheimer’s Disease Compared to Mild Cognitive Impairment: An Electrophysiological Study

Some researchers have suggested that the default mode network (DMN) plays an important role in the pathological mechanisms of Alzheimer’s disease (AD). To examine whether the cortical activities in DMN regions show significant difference between mild AD from mild cognitive impairment (MCI), electrophysiological responses were analyzed from 21 mild Alzheimer’s disease (AD) and 21 mild cognitive impairment (MCI) patients during an eyes closed, resting-state condition. The spectral power and functional connectivity of the DMN were estimated using a minimum norm estimate (MNE) combined with fast Fourier transform and imaginary coherence analysis. Our results indicated that source-based EEG maps of resting-state activity showed alterations of cortical spectral power in mild AD when compared to MCI. These alterations are characteristic of attenuated alpha or beta activities in the DMN, as are enhanced delta or theta activities in the medial temporal, inferior parietal, posterior cingulate cortex and precuneus. With regard to altered synchronization in AD, altered functional interconnections were observed as specific connectivity patterns of connection hubs in the precuneus, posterior cingulate cortex, anterior cingulate cortex and medial temporal regions. Moreover, posterior theta and alpha power and altered connectivity in the medial temporal lobe correlated significantly with scores obtained on the Mini-Mental State Examination (MMSE). In conclusion, EEG is a useful tool for investigating the DMN in the brain and differentiating early stage AD and MCI patients. This is a promising finding; however, further large-scale studies are needed.