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This study aims to construct a novel risk score model based on glycolysis-related genes in osteosarcoma and to build and validate a prognostic model for predicting overall survival of patients with osteosarcoma. The transcriptome data and corresponding clinical data of patients with osteosarcoma were obtained from The Cancer Genome Atlas (TCGA) as the training set, and from Gene Expression Omnibus (GEO) database as the validation set. Univariate Cox regression analysis was used to screen the prognostic glycolysis-related genes. The risk coefficient of each glycolysis-related gene was calculated using LASSO regression analysis. Using the median risk score as the cut-off point, patients were divided into high-risk and low-risk groups. Kaplan-Meier survival analysis was used to determine whether there was a significant difference in the overall survival between the two groups. The nomogram was constructed according to the results of multivariate Cox regression. The C-index was calculated, the calibration chart, clinical decision curve and receiver operating characteristic curve were drawn to evaluate the predictive performance of the nomogram. We performed Gene Ontology and Kyoto encyclopedia of genes and genomics enrichment analysis to explore the potential mechanism of prognostic-related glycolysis genes in osteosarcoma. A total of 88 and 53 cases were obtained from the TCGA and GEO database, respectively. A total of 10 key glycolytic genes related to prognosis were screened out. The Kaplan-Meier survival curve revealed that the overall survival of the high-risk group was significantly shorter than that of the low-risk group. The C indices of the training set and the verification set were 0.882 and 0.828, respectively. Our findings will provide further understanding of clinical prognostic outcomes of osteosarcoma patients.

Desertification is the impoverishment of arid, semiarid, and some subhumid ecosystems. The assessment of global scale desertification vulnerability to climate change and human activity is important to help decision makers formulate the best strategies for land rehabilitation and combat global desertification in sensitive areas. There is no global desertification vulnerability map that considers both climate change and human activities. The main aim of this study was to construct a new index, the global desertification vulnerability index (GDVI), by combining climate change and human activity, provide another perspective on desertification vulnerability on a global scale, and project its future evolution. Using the probability density function of the GDVI, we classified desertification vulnerability into four classes: very high, high, medium, and low. The results of the analysis indicated that areas around deserts and barren land have a higher risk of desertification. Areas with a moderate, high, and very high desertification risk accounted for 13%, 7%, and 9% of the global area, respectively. Among the representative concentration pathways (RCPs), RCP8.5 projected that the area of moderate to very high desertification risk will increase by 23% by the end of this century. The areas where desertification risks are predicted to increase over time are mainly in Africa, North America, and the northern areas of China and India.

This study explores the near-surface air temperature (TAS) prediction skills at different time scales via coupled climate models that were involved in the Coupled Model Intercomparison Project phase 5 (CMIP5). The simulation skills of the global mean TAS are first assessed between the observations and models; then, the temporal variability is separated into three parts (the linear trend, decadal variability and inter-annual variability), and each part is compared with the observations. It is found that the global mean TAS anomaly and the decadal variability are well captured by the model, while the inter-annual variability is poorly presented. In all the three parts of different time scales, there are larger differences among the 18 models, and the ensemble mean of CMIP5 is the closest to the observations. Besides, the TAS decadal variability is better presented for global ocean than for global land. In the assessment of climate oscillation, it is found that the models can well reproduce the TAS decadal variation patterns correlated with the Pacific Decadal Oscillation (PDO) and the inter-annual variation patterns correlated with El Nino-Southern Oscillation (ENSO) but poor for the decadal variation patterns related to the Atlantic Multidecadal Oscillation (AMO). This study provides a reference assessing the simulation skills of climate models and an indicator evaluating the advantage of CMIP6 in comparison with CMIP5.

Background Central nervous system (CNS) malignancies are the most common solid tumors among children, and novel therapies are needed to help improve survival. Pomalidomide is an immunomodulatory agent that displays antiangiogenic and cytotoxic activity, making it an appropriate candidate to explore in pediatric CNS tumors. Methods A phase 1 first in pediatric trial of pomalidomide was conducted in children with recurrent, progressive, and refractory CNS tumors. The primary objective was to determine the maximum tolerated dose (MTD) and/or recommended phase 2 dose (RP2D) when given orally once daily for 21 consecutive days of a 28-day cycle. Once the MTD was established, 12 additional patients were enrolled on expansion cohorts based on age and steroid use. Results Twenty-nine children were enrolled and 25 were evaluable for dose-limiting toxicity (DLT). The MTD was 2.6 mg/m2 (dose level 2). Four DLTs were observed in three patients at dose level 3 (3.4 mg/m2 ) includeding grade 3 diarrhea, grade 3 thrombocytopenia, grade 3 lung infection, and grade 4 neutropenia. The most common adverse events were grade 1 and 2 myelosuppression. One patient with an oligodendroglioma had stable disease for nine cycles, and a second patient with an anaplastic pleomorphic xanthoastrocytoma achieved a sustained partial response. Immunologic analyses suggested that pomalidomide triggers immunomodulation. Conclusions The MTD of pomalidomide is 2.6 mg/m2 . It was well tolerated, and immune correlates showed a serum immune response. These data led to an industry-sponsored phase 2 trial of pomalidomide monotherapy in children with recurrent brain tumors (NCT03257631).

BACKGROUND Pea aphid (Acyrthosiphon pisum Harris) is one of the major pests in alfalfa crops, causing significant yield losses. (E)-β-farnesene (EβF), an alarm pheromone released by pea aphid, is generic to many species of aphids, and is used to minimize potential danger from predators and parasitoids by avoiding the source of the pheromone. RESULTS In this study, EβF synthase gene was constructed into a plant expression vector, and overexpressed in alfalfa (Medicago sativa L.), with expression among transgenic lines confirmed by qRT-PCR. Subcellular localization analysis showed that EβF synthase gene was expressed in the plasma membrane and nucleus of the leaf. GC/MS of extraction from transgenic alfalfa indicated emission of EβF ranging from 5.92 to 13.09 ng day-1 g-1 fresh tissue. Behavior assays in Y-olfactometers demonstrated that transgenic alfalfa expressing AaEβF gene could repel pea aphids, with aphids taking a significantly longer time to select a transgenic line compared with the control line (P < 0.01). CONCLUSION We have demonstrated a potentially valuable strategy of using EβF synthase genes for aphid control in alfalfa. © 2018 Society of Chemical Industry.

The ability of climate models to simulate the Pacific Decadal Oscillation (PDO) and its global teleconnections is examined using the outputs of 20 Coupled Model Intercomparison Project (CMIP5) models from historical experiments. It is shown that the global warming trend is reproduced by the models, but there is a considerable difference between the models in the PDO region. The standard deviation of detrended sea surface temperature anomalies (SSTAs) in the models is similar to that of the observations, especially in the central and eastern equatorial Pacific and the North Pacific, which are the regions closely associated with the PDO and El Nino-Southern Oscillation. The globally averaged SSTA during 1900-1940 in the CMIP5 models and observations showed large divergence, which is mainly due to the SSTA in the PDO region. The most significant cycle of the PDO indexes in most of the models had a 60-80 years period, which is different from the observed PDO period (40-60 years). However, the models perform better for the spatial pattern of the PDO, and 90% of the spatial correlations between the models and observations of the spatial pattern of the PDO are above 0.8. In addition, the models can simulate the basic correlation between the PDO and Pacific SSTA variability, but most of them overestimate the relationship in the Indian and Atlantic Oceans. The CMIP5 models are better at simulating the impact of the PDO on winter precipitation in southern North America but are less accurate in simulating summer precipitation in eastern China. This is probably because most of the models are not accurate in simulating the impacts of the PDO on the western Pacific subtropical high and the East Asian summer monsoon.

As the recent global warming hiatus has attracted worldwide attention, we examined the robustness of the warming hiatus in China and the related dynamical mechanisms in this study. Based on the results confirmed by the multiple data and trend analysis methods, we found that the annual mean temperature in China had a cooling trend during the recent global warming hiatus period, which suggested a robust warming hiatus in China. The warming hiatus in China was dominated by the cooling trend in the cold season, which was mainly induced by the more frequent and enhanced extreme-cold events. By examining the variability of the temperature over different time scales, we found the recent warming hiatus was mainly associated with a downward change of decadal variability, which counteracted the background warming trend. Decadal variability was also much greater in the cold season than in the warm season, and also contributed the most to the previous accelerated warming. We found that the previous accelerated warming and the recent warming hiatus, and the decadal variability of temperature in China were connected to changes in atmospheric circulation. There were opposite circulation changes during these two periods. The westerly winds from the low to the high troposphere over the north of China all enhanced during the previous accelerated warming period, while it weakened during the recent hiatus. The enhanced westerly winds suppressed the invasion of cold air from the Arctic and vice versa. Less frequent atmospheric blocking during the accelerated warming period and more frequent blocking during the recent warming hiatus confirmed this hypothesis. Furthermore, variation in the Siberian High and East Asian winter monsoon season supports the given conclusions.

The modulated annual cycle (MAC) of the Indo-Pacific warm pool (IPWP) heat centre location is investigated using the empirical mode decomposition-ensemble empirical mode decomposition method. The MAC and its interannual variability mainly affect the zonal and vertical locations of the heat centre; in fall and winter of El Nino years, the heat centre moves eastward from its normal location, with very little change in its meridional position. Four patterns of the heat centre trajectory in the IPWP are identified using the self-organizing map algorithm. Patterns 1 and 3 are both similar to a saddle, but pattern 1 is more winding. The shapes of patterns 2 and 4 are similar, but tilt in different directions: pattern 2 tilts southwest whereas pattern 4 tilts west. Of all the four patterns, the persistence of pattern 2 is generally relatively high. The trajectory of the heat centre develops in the sequence of patterns: 1-2-4-3-1. Pattern 1 (pattern 4) is related to the cold (warm) phase of the El Nino-Southern Oscillation (ENSO), while pattern 2 (pattern 3) corresponds to the negative (positive) phase of Indian Ocean dipole (IOD). The sequence of patterns in the trajectory of the heat centre in the IPWP is related to the IOD-ENSO interactions on a biennial timescale.

The surface air temperature (SAT) trends from historical simulations of the Coupled Model Intercomparison Project Phase 5 (CMIP5) were compared with observations for the period of 1955-2004. The observed spatial pattern of SAT trends was strikingly different from the CMIP5-historical simulations over mid- and high-latitude Northern Hemisphere. The strongest observed warming for the Eurasian Continent was over mid latitudes. However, the CMIP5 historical simulations indicated enhanced warming over higher latitudes, and the warming trends increased from low to higher latitudes. The zonal mean SAT trends indicated overestimated warming in high-latitude and underestimated warming in mid-latitude land over Northern Hemisphere in CMIP5 historical simulations, which resulted in opposite trends in the meridional temperature gradient over high latitudes compared with observations. The overestimated Arctic and underestimated Eurasia mid-latitude warming only occurred in cold season. Further comparison of the results of CMIP5 models from the Atmospheric Model Intercomparison Project and historical simulations revealed that model bias in sea surface temperature and the exaggerated response of temperature change to Arctic sea ice decline are possible reasons for poorly simulated Arctic and Eurasia mid-latitude temperature change.

In diffusion magnetic resonance imaging dMRI, the accuracy of fiber tracking and analysis depends directly on that of intravoxel fiber architecture reconstruction. Several methods have been proposed that estimate intravoxel fiber architecture using low angular resolution acquisitions owing to their shorter acquisition time and relatively low b-values. But these methods are highly sensitive to noise. We propose an approach to estimating intravoxel fiber architecture in low angular resolution dMRI. The method consists in using a constrained compressed sensing CCS method, also known as crossing fiber angular resolution of intravoxel architecture CFARI technique, in combination with multitensor adaptive smoothing in which a diffusion-weighted DW image smoothing scheme is constructed according to the properties of the multitensor field estimated using CFARI. The results on synthetic, physical phantom and real brain DW images show that the proposed method is able to better resolve fiber architectures while correctly preserving image edge information, which provides a new tool for investigating the microstructures of biological tissues and for fiber tractography. © 2015 Wiley Periodicals, Inc. Int J Imaging Syst Technol, 25, 285-296, 2015

Bone tissue engineering using biomaterial scaffolds and culture-expanded osteoprogenitor cells has been demonstrated in several studies; however, it is not yet a clinical reality. One challenge is the optimal design of scaffolds for cell delivery and the identification of scaffold parameters that can delineate success and failure in vivo. Motivated by a previous experiment in which a batch of lyophilized collagen-hydroxyapatite (HA) scaffolds displayed modest bone formation in vivo, despite having large pores and high porosity, we began to investigate the effect of scaffold permeability on bone formation. Herein, we fabricated scaffolds with a permeability of 2.17 ± 1.63 × 10-9 m4 /(N s) and fourfold higher using a sacrificial gelatin porogen. Scaffolds were seeded with mouse bone marrow stromal cells carrying a fluorescent reporter for osteoblast differentiation and implanted into critical-size calvarial defects in immunodeficient mice. The porogen scaffold group containing a 1:1 ratio of solids to beads was significantly more radiopaque than the scaffold group without the bead porogen 3 weeks after implantation. Quantitative histomorphometry uncovered the same trend between the 1:1 group and scaffolds without porogen found in the radiographic data; however, this was not statistically significant here. Taken together, the X-ray and histology suggest that the 1:1 ratio of porogen to scaffold solids, resulting in a fourfold increase in permeability, may enhance bone formation when compared to scaffolds without porogen. Scaffold permeability can be a useful quality control measure before implantation and this practice should improve the consistency and efficacy of cell-based bone tissue engineering. © 2015 Wiley Periodicals, Inc. J Biomed Mater Res Part B: Appl Biomater, 104B: 1580-1590, 2016.

Gaussian beam migration is a versatile imaging method for geologically complex land areas, which overcomes the limitation of Kirchhoff migration in imaging multiple arrivals and has no steep-dip limits of one-way wave-equation migration. However, its imaging accuracy depends on the geometry of Gaussian beam that is determined by the initial parameter of dynamic ray tracing. As a result, its applications in exploration areaswith strong variations in topography and near-surface velocity are limited. Combined with the concept of Fresnel zone and the theory of wave-field approximation in effective vicinity, we present a more robust common-shot Fresnel beam imaging method for complex topographic land areas in this paper. Compared with the conventional Gaussian beam migration for irregular topography, our method improves the beam geometry by limiting its effective half-width with Fresnel zone radius. Moreover, through a quadratic travel-time correction and an amplitude correction that is based on the wave-field approximation in effective vicinity, it gives an accurate method for plane-wave decomposition at complex topography, which produces good imaging results in both shallow and deep zones. Trials of two typical models and its application in field data demonstrated the validity and robustness of our method.

Osteoprogenitor cells combined with supportive biomaterials represent a promising approach to advance the standard of care for bone grafting procedures. However, this approach faces challenges, including inconsistent bone formation, cell survival in the implant, and appropriate biomaterial degradation. We have developed a collagen-hydroxyapatite (HA) scaffold that supports consistent osteogenesis by donor-derived osteoprogenitors, and is more easily degraded than a pure ceramic scaffold. Herein, the material properties are characterized as well as cell attachment, viability, and progenitor distribution in vitro. Furthermore, we examined the biological performance in vivo in a critical-size mouse calvarial defect. To aid in the evaluation of the in-house collagen-HA scaffold, the in vivo performance was compared with a commercial collagen-HA scaffold (Healos(®) , Depuy). The in-house collagen-HA scaffold supported consistent bone formation by predominantly donor-derived osteoblasts, nearly completely filling a 3.5 mm calvarial defect with bone in all samples (n = 5) after 3 weeks of implantation. In terms of bone formation and donor cell retention at 3 weeks postimplantation, no statistical difference was found between the in-house and commercial scaffold following quantitative histomorphometry. The collagen-HA scaffold presented here is an open and well-defined platform that supports robust bone formation and should facilitate the further development of collagen-hydroxyapatite biomaterials for bone tissue engineering.

On the basis of the datasets obtained for the monthly turbulent heat flux (1984-2009) from the Objectively Analyzed Air-Sea Heat Flux (OAFlux), the radiation flux from the International Satellite Cloud Climatology Project (ISCCP), the variability characteristics of the net heat flux (Qnet) over the Kuroshio System (KS) and its relationship with the climate in China were studied. The results reveal that except for a steady enhancement in the period 1984-2009, the boreal winter Qnet over the KS is characterized by obvious interannual variation of the period quasi-5 year as well as decadal variability shifting from negative to positive anomalies in the mid-1990s. In the wintertime, the increasing KS Qnet is primarily responsible for the intensification of the East Asia winter monsoon (EAWM) via a deepening of the Aleutian low and an enhancement of the Siberia high and has a correlation coefficient of 0.72 with a 1-month delay. The enhanced-EAWM induces colder winters in Northeast China and higher Qnet over the KS by carrying significantly greater amounts of cold air mass. During the low Qnet winter, the EAWM is weakened, and the southwesterly wind that contains abundant water vapour enhances and pushes toward southern China, thereby bringing heavier rainfall. The anomalous Qnet over the KS in the wintertime lasts until the following spring with a weaker relative intensity. In the spring after the low KS Qnet winter, the anomalous easterly wind transfers colder air masses from the Sea of Japan to the North China and Yellow-Huaihe regions and then cools these regions. The warmer and wetter southwesterlies along the northwestern flank of the anomalous anticyclone east of Taiwan Island meet these colder easterlies accompanied by an anomalous upward motion, thereby inducing an anomalous northwest-southeast precipitation band in the central and eastern region of China, especially in the Yangtze-Huaihe region.

In this study, nine decadal-scale surface air temperature (SAT) patterns in China during 1902-2007 were obtained from Climatic Research Unit data using the self-organizing map based on the ensemble empirical mode decomposition. To further investigate the relationship between decadal SAT patterns in China and the Indo-Pacific warm pool (IPWP), we aggregated the selected nine neurons into three significant types based on the similarities of the reference vectors using a hierarchical agglomerative clustering approach. Among the three patterns, Pattern 1 is a cold pattern and Pattern 3 is a warm pattern. Pattern 2 is a medium mode, in which the west of China is cold, but eastern China is warm. The relationship between the IPWP and SAT in China at the decadal scale can be summarized as follows. When the IPWP is warmer, easterly wind anomalies are stronger over the equatorial Pacific Ocean, the IPWP shrinks westwards predominantly and the heat centre is to the west. Furthermore, easterly wind anomalies strengthen the trade winds, so that poleward energy transport by the ocean increases, while poleward energy transport by the atmosphere decreases in the tropics. Meanwhile, the Aleutian Low and East Asian trough strengthen, and the meridional circulation is dominated, which is of benefit to cold air from the high latitude that move to the southeast, making the temperature in China colder. In contrast, the warm pool is colder, and the westerly wind anomalies are prevailing, making the IPWP extending eastward. Zonal circulation is dominant in the mid-latitudes, which weakens the cold airflow into China and leads to warmer temperatures there.

Stretchable conductors are the basic units of advanced flexible electronic devices, such as skin‐like sensors, stretchable batteries and soft actuators. Current fabrication strategies are mainly focused on the stretchability of the conductor with less emphasis on the huge mismatch of the conductive material and polymeric substrate, which results in stability issues during long‐term use. Thermal‐radiation‐assisted metal encapsulation is reported to construct an interlocking layer between polydimethylsiloxane (PDMS) and gold by employing a semipolymerized PDMS substrate to encapsulate the gold clusters/atoms during thermal deposition. The stability of the stretchable conductor is significantly enhanced based on the interlocking effect of metal and polymer, with high interfacial adhesion (>2 MPa) and cyclic stability (>10 000 cycles). Also, the conductor exhibits superior properties such as high stretchability (>130%) and large active surface area (>5:1 effective surface area/geometrical area). It is noted that this method can be easily used to fabricate such a stretchable conductor in a wafer‐scale format through a one‐step process. As a proof of concept, both long‐term implantation in an animal model to monitor intramuscular electric signals and on human skin for detection of biosignals are demonstrated. This design approach brings about a new perspective on the exploration of stretchable conductors for biomedical applications. NRF (Natl Research Foundation, S’pore) ASTAR (Agency for Sci., Tech. and Research, S’pore) Accepted version

One of the main distresses that occur in the road surface is a result of pavement cracking. This article proposes a new pavement crack detection method that combines two-dimensional (2D) gray-scale images and three-dimensional (3D) laser scanning data based on Dempster-Shafer (D-S) theory. The 2D gray-scale image and 3D laser scanning data are modeled as a mass function in evidence theory in this model and the 2D and 3D detection results for pavement cracks are fused at the decision-making level. The proposed method takes advantage of the respective merits of 2D images and 3D laser scanning data and therefore improves the pavement crack detection accuracy and reduces recognition error rate compared to 2D image intensity-based methods. This article discusses how objective and accurate detection or evaluation for these cracks is an important task in the pavement maintenance and management for state highway departments of transportation.

AgxMn8O16 (Ag-OMS-2) and KxMn8O16 (K-OMS-2) were investigated as high voltage cathode materials for Mg based batteries. Both MxMn8O16 materials delivered high initial capacities (>180 mA h g−1), and KxMn8O16 showed high cycle stability with a reversible capacity of >170 mA h g−1 after 20 cycles.

Based on the data of France DEMETER (Detection of Electro-Magnetic Emissions Transmitted from Earthquake Regions) satellite, we have made identification to the level 1 data using level 2 picture, moving median processing, analyses of latitude changes and spatial differences. We found some anomalies in the ionosphere above the epicenter of the 27 February 2010 Chile M8.8 earthquake. In an area 1500 km apart from the epicenter, electron density rose on 20 February 2010. The electron density declined on 24th. The electric, magnetic fields and some plasma parameters disturbed at the same time on 25th and 26th. Besides, on 26th, electron density of 2 orbits exceeded the background values. The electric field spectrum around the magnetic equator on 27th began to drop 4 hours before the great earthquake, and meanwhile strong perturbations of some plasma parameters occurred.

A novel and convenient transformation for the regiospecific synthesis of functionalized imidazo[1,2-a]pyridine aldehydes/ketones and 3-vinyl imidazo[1,2-a]pyridines has been developed via copper(I)- and palladium(II)-catalyzed cyclization. The one-pot reaction proceeds smoothly with commercially available catalysts and affords the products in moderate to good yields. It represents an efficient approach for the formation of C–N, C═O, and C═C bonds under mild conditions.

Substrates such as vinylarenes (II) tend to form α-products (III), while acrylates (IV) tend to form β-products (V).

Manganese oxide (α-MnO2) has been considered a promising energy material, including as a lithium-based battery electrode candidate, due to its environmental friendliness. Thanks to its unique 1D [2 × 2] tunnel structure, α-MnO2 can be applied to a cathode by insertion reaction and to an anode by conversion reaction in corresponding voltage ranges, in a lithium-based battery. Numerous reports have attributed its remarkable performance to its unique tunnel structure; however, the precise electrochemical reaction mechanism remains unknown. In this study, finding of the lithiation mechanism of α-MnO2 nanowire by in situ transmission electron microscopy (TEM) is reported. By elaborately modifying the existing in situ TEM experimental technique, rapid lithium-ion diffusion through the tunnels is verified. Furthermore, by tracing the full lithiation procedure, the evolution of the MnO intermediate phase and the development of the MnO and Li2O phases with preferred orientations is demonstrated, which explains how the conversion reaction occurs in α-MnO2 material. This study provides a comprehensive understanding of the electrochemical lithiation process and mechanism of α-MnO2 material, in addition to the introduction of an improved in situ TEM biasing technique.

A systematic examination of the dynamical relationship between the North Atlantic Oscillation (NAO) and atmospheric blocking episodes in the North Atlantic during winter is undertaken. Employing the blocking criteria, as defined by Tibaldi and Molteni (1990), we first establish a statistical relationship, through compositing and linear regression analysis, between the two phenomena. The results show that the frequency of blocking formations in the North Atlantic region is sensitive to the phase of the NAO. Sixty-seven percent more winter blocking days are observed during the negative than the positive phase of the NAO. The lifetime of blocking episodes is also sensitive to the phase of the NAO. When the NAO is in the negative phase, the distribution of the length of blocking varies considerably. The average length of blocking during the negative phase is about 11 days, which is nearly twice as long as the 6-day length observed during the positive phase of the NAO. The NAO accounts for about 30% of the variation in the wintertime North Atlantic blocking episodes. We propose a conceptual model that strengthens the statistical association and offers an explanation for a dynamical connection between the occurrences of blocking and the NAO in the North Atlantic. Application of a low-order theoretical model by Charney and DeVore (1979) and an analysis of Northern Hemisphere observed surface temperature suggest that the NAO-related difference in blocking frequency and persistence are associated with changes in the zonally asymmetric thermal forcing which, to a large extent, is determined by the phase of the NAO. For the negative phase of the NAO, the distribution of the surface air temperature anomaly is the distinctive ‘warm ocean/cold land’ pattern related to the resonance forcing of topography and creates a dynamical environment favourable for the formation and persistence of blocks. For the positive phase of the NAO, on the other hand, the distribution of the surface air temperature anomalies is the distinctive ‘cold ocean/warm land’ pattern, which reduces or destroys the resonance forcing of topography and is unfavourable for the development and persistence of blocks. Copyright © 2001 Crown in the right of Canada. Published by John Wiley & Sons, Ltd.

Reactive oxygen species (ROS) have been implicated as mediators of tumor necrosis factor-alpha (TNF) -induced apoptosis. In addition to leading to cell death, ROS can also promote cell growth and/or survival. We investigated these two roles of ROS in TNF-induced endothelial cell apoptosis. Human umbilical vein endothelial cells (HUVECs) stimulated with TNF produced an intracellular burst of ROS. Adenoviral-mediated gene transfer of a dominant negative form of the small GTPase Rac1 (Rac1N17) partially suppressed the TNF-induced oxidative burst without affecting TNF-induced mitochondrial ROS production. HUVECs were protected from TNF-induced apoptosis. Expression of Rac1N17 blocked TNF-induced activation of nuclear factor-kappa B (NF-kappaB), increased activity of caspase-3, and markedly augmented endothelial cell susceptibility to TNF-induced apoptosis. Direct inhibition of NF-kappaB through adenoviral expression of the super repressor form of inhibitor of kappaBalpha (I-kappaB S32/36A) also increased susceptibility of HUVECs to TNF-induced apoptosis. Rotenone, a mitochondrial electron transport chain inhibitor, suppressed TNF-induced mitochondrial ROS production, proteolytic cleavage of procaspase-3, and apoptosis. These findings show that Rac1 is an important regulator of TNF-induced ROS production in endothelial cells. Moreover, they suggest that Rac1-dependent ROS, directly or indirectly, lead to protection against TNF-induced death, whereas mitochondrial-derived ROS promote TNF-induced apoptosis.

In this study, Multiresolution Fourier Transform (MFT) spectral analysis is employed to resolve the temporal structure of the variation of the North Atlantic Oscillation (NAO) in terms of various frequency components. The NAO index displays fluctuations on multiple timescales, resulting in an MFT spectrum characterized by the occurrences of distinct frequency bands at certain times in the record. These frequency bands are examined within the context of annual to interdecadal spectral components. The relative contribution by each of these spectral components toward the overall NAO variability varies with time. Phase analysis of the spectrum demonstrates that, in addition to some apparent 'random' fluctuations, the phase of each of the spectral components on occasions exhibits relatively constant value over a period of time (from a few years to a decade). In addition, a significant coherent relationship between the NAO and the North Atlantic sea surface temperature (SST) is found at interannual and interdecadal timescales. Some evidence has also been found to suggest that the phase of the interdecadal component of the NAO is itself modulated by the North Atlantic SST at a timescale of about 60 years.

The seasonal variation of intraseasonal oscillations have been studied on a zonally symmetric all-land planet in the absence of external forcing, using the second version of the NCAR community climate model (CCM2, R15). Analysis of both 15-year perpetual and seasonal simulations indicates the seasonal cycle strongly modulates the intraseasonal oscillations. The averaged period of oscillation in seasonal simulation is 50 days, while it is 40 days in the perpetual run. It also has larger amplitudes during the winter than during the summer. Statistics of phase variation show that the probability distribution of phase changes has also an obvious seasonal variation, especially in the mid-latitudes, where the probability distribution is narrow centered 40‐50 days in period in the winter hemisphere, but is broad in the summer hemisphere. © 1998 Royal Meteorological Society.