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1.
The environmental impacts of data centers that provide information and communication technologies (ICTs) services are strongly related to electricity generation. With the increasing use of ICT, many data centers are expected to be built, causing more absolute impacts on the environment. Given that electricity distribution networks are very complex and dynamic systems, an environmental evaluation of future data centers is uncertain. This study proposes a new approach to investigate the consequences of future data center deployment in Canada and optimize this deployment based on the Energy 2020 technoeconomic model in combination with life cycle assessment methodology. The method determines specific electricity sources that will power the future Canadian data centers and computes related environmental impacts based on several indicators. In case‐study scenarios, the largest deployment of data centers leads to the smallest impact per megawatt of data centers for all of the environmental indicators. It is found that an increase in power demand by data centers would lead to a reduction in electricity exports to the United States, driving the United States to generate more electricity to meet its energy demand. Given that electricity generation in the United States is more polluting than in Canada, the deployment of data centers in Canada is indirectly linked to an increase in overall environmental impacts. However, though an optimal solution should be found to mitigate global greenhouse gas emissions, it is not clear whether the environmental burden related to U.S. electricity generation should be attributed to the Canadian data centers.  相似文献   

2.
Beyond Energy     
This article is based on the first study worldwide to analyze materials present in the equipment of data centers. The study develops a methodology that allows the calculation of the number of data centers of the various size classes and their average equipment with information technology (IT) components and infrastructure elements, such as air‐conditioning systems and power supplies. This enables detailed statements to be made on the materials present in the equipment of approximately 53,000 data centers in Germany. In 2008, the total amount of materials in the equipment of data centers in Germany was 110,300 tonnes (t). IT equipment (servers, storage equipment, and network) accounted for 37,500 t (34%), racks and containments for 30,700 t (28%), cooling and air‐conditioning systems for 12,000 t (11%), and the power infrastructure for 30,000 t (27%). A comprehensive analysis of the type of materials being used yielded the following values: Approximately 58,400 t of iron, 18,600 t of copper, 11,600 t of circuit boards, 11,100 t of plastics, 7,400 t of aluminum, and 6,500 t of miscellaneous materials were present in German data centers. The electronic material contained 1.8 t of gold, 7.5 t of silver, and 0.8 t of palladium. Because it can be assumed that prices for precious metals, and also for bulk metals, will continue to rise, the recovery of raw materials from the IT devices of data centers is an interesting option. Additionally, the development of appropriate product design and recycling strategies for servers and storage units should be implemented.  相似文献   

3.
The intranucleolar distribution of phosphoproteins B23 and C23 was visualized simultaneously by post-embedding immunoelectron microscopy in HeLa cell nucleoli, using specific antibodies. The data show that proteins B23 and C23 co-localize to the same nucleolar compartments, i.e., the dense fibrillar component and the granular component. Neither of the two antibodies is significantly associated with the fibrillar centers in these cells, although the fibrillar centers appear positive after silver staining. These findings suggest that other unidentified components must be responsible for the silver staining observed in the fibrillar centers of interphase nucleoli. The results are discussed in the light of previously reported data obtained by preembedding immunolabeling techniques and by silver staining, which both suggested a localization of protein C23 inside the fibrillar centers.  相似文献   

4.
范泽孟  范斌 《生态学报》2019,39(14):5028-5039
欧亚大陆复杂多样的植被生态系统在全球气候变化的驱动下,其时空分布格局将发生系列的偏移变化,进而对欧亚大陆"一带一路"沿线国家和地区的生态环境产生重要影响。如何从全球气候变化驱动的角度来实现欧亚大陆植被生态系统时空偏移趋势的模拟分析,已成为"一带一路"沿线国家和地区生态环境研究的热点科学问题之一。在对HLZ生态系统模型进行改进和构建植被生态系统平均中心时空偏移分析模型的基础上,基于欧亚大陆的气候观测数据(1981—2010年)和CMIP5 RCP2.6、RCP4.5和RCP8.5三种情景数据(2011—2100年),实现欧亚大陆植被生态系统平均中心时空偏移趋势的模拟分析。结果表明:欧亚大陆植被生态系统平均中心主要分布在欧亚大陆的中部和南部地区;3种气候情景下,欧亚大陆的亚热带干旱森林、暖温带湿润森林、亚热带有刺疏林、亚热带潮湿森林、冷温带潮湿森林、寒温带湿润森林、冷温带湿润森林、亚热带湿润森林、暖温带干旱森林、亚极地/高山湿润苔原和极地/冰原等植被生态系统的平均中心偏移幅度大于其他植被生态系统类型;欧亚大陆植被生态系统在RCP8.5情景下的植被生态系统平均中心偏移幅度大于其他两种情景;在2011—2100年期间,3种气候变化情景下,欧亚大陆植被生态系统平均中心整体上将呈向北偏移的变化趋势。  相似文献   

5.
Cloud computing took a step forward in the efficient use of hardware through virtualization technology. And as a result, cloud brings evident benefits for both users and providers. While users can acquire computational resources on-demand elastically, cloud vendors can also utilize maximally the investment costs for data centers infrastructure. In the Internet era, the number of appliances and services migrated to cloud environment increases exponentially. This leads to the expansion of data centers, which become bigger and bigger. Not just that these data centers must have the architecture with a high elasticity in order to serve the huge upsurge of tasks and balance the energy consumption. Although in recent times, many research works have dealt with finite capacity for single job queue in data centers, the multiple finite-capacity queues architecture receives less attention. In reality, the multiple queues architecture is widely used in large data centers. In this paper, we propose a novel three-state model for cloud servers. The model is deployed in both single and multiple finite capacity queues. We also bring forward several strategies to control multiple queues at the same time. This approach allows to reduce service waiting time for jobs and managing elastically the service capability for the whole system. We use CloudSim to simulate the cloud environment and to carry out the experiments in order to demonstrate the operability and effectiveness of the proposed method and strategies. The power consumption is also evaluated to provide insights into the system performance in respect of performance-energy trade-off.  相似文献   

6.
We report on results from whole-exome sequencing (WES) of 1,039 subjects diagnosed with autism spectrum disorders (ASD) and 870 controls selected from the NIMH repository to be of similar ancestry to cases. The WES data came from two centers using different methods to produce sequence and to call variants from it. Therefore, an initial goal was to ensure the distribution of rare variation was similar for data from different centers. This proved straightforward by filtering called variants by fraction of missing data, read depth, and balance of alternative to reference reads. Results were evaluated using seven samples sequenced at both centers and by results from the association study. Next we addressed how the data and/or results from the centers should be combined. Gene-based analyses of association was an obvious choice, but should statistics for association be combined across centers (meta-analysis) or should data be combined and then analyzed (mega-analysis)? Because of the nature of many gene-based tests, we showed by theory and simulations that mega-analysis has better power than meta-analysis. Finally, before analyzing the data for association, we explored the impact of population structure on rare variant analysis in these data. Like other recent studies, we found evidence that population structure can confound case-control studies by the clustering of rare variants in ancestry space; yet, unlike some recent studies, for these data we found that principal component-based analyses were sufficient to control for ancestry and produce test statistics with appropriate distributions. After using a variety of gene-based tests and both meta- and mega-analysis, we found no new risk genes for ASD in this sample. Our results suggest that standard gene-based tests will require much larger samples of cases and controls before being effective for gene discovery, even for a disorder like ASD.  相似文献   

7.
Despite the fact that the fibrillar centers of the nucleolus and the chromosomal nucleolar organisers (NORs) are similarly stained with the NOR-silver technique, there remain some questions about the identification of fibrillar centers as NORs. The distinct delineation of the fibrillar centers in porcine thyroid cells allowed us to determine whether there was a numerical equivalence or correlation between fibrillar centers and NORs. Hybridization in situ and silver staining performed on pig chromosomes showed that pairs 8 and 10 contained rDNA sites. Silver staining of thyroid cells in electron microscopy showed that the fibrillar centers and their surrounding layer of dense fibrils were the sites of silver deposit. Chromatin fibers were demonstrated within the fibrillar centers through the aid of the osmiumammine reaction and with the oxidized diaminobenzidine technique. It was observed that in cultured thyroid cells the fibrillar centers could be identified in the light microscope as argyrophilic spherules, and easily counted. The number of fibrillar centers was variable according to culture conditions. In cells cultured for 5 hr, the mean number of fibrillar centers was 1.7. After 5 days of culture, the number of fibrillar centers increased, reaching a mean value of 5.93. When thyroid cells were stimulated with thyrotropin, the number of fibrillar centers again increased to a mean value of 7.54. These results demonstrate that the relationship between fibrillar centers and NORs is not a simple proportionality: the number of fibrillar centers increases with increased cellular activity. These data imply that in active cells each NOR may pass through several fibrillar centers.  相似文献   

8.
Cloud computing and web emerging applications have created the need for more powerful data centers. These data centers need high bandwidth interconnects that can sustain the high interaction between the web-, application- and database-servers. Data center networks based on electronic packet switches will have to consume excessive power in order to satisfy the required communication bandwidth of future data centers. Optical interconnects have gained attention recently as a promising energy efficient solution offering high throughput, low latency and reduced energy consumption compared to current networks based on commodity switches. This paper presents a comparison on the power consumption of several optical interconnection schemes based on AWGRs, Wavelength Selective Switches (WSS) or Semiconductor Optical Amplifiers (SOAs). Based on a thorough analysis of each architecture, it is shown that optical interconnects can achieve at least an order of magnitude higher energy efficiency compared to current data center networks based on electrical packet based switches and they could contribute to greener IT network infrastructures.  相似文献   

9.
The work studies effects of elevated gravitation on activity of locomotor centers in the locust Locusta migratoria L. Under effect of the increased gravity field the excitation of the motor centers that provide activity of the locus wing apparatus was shown to decrease. Analysis of the data obtained has allowed us concluding that the higher CNS centers (subesophageal ganglion) produce at least two types of excitatory (stimulatory) effects on segmental centers, one of the types affecting motor centers in the rest state, the other, in the active state. We believe that it is the impulses of the second type that are inhibited under effect of the increased radial acceleration on the organism. There is every reason to think that an important role in these processes is played by peculiar structures of the supraesophageal ganglion protocerebrum: mushroom bodies and the central complex that regulates activity of the locust segmental centers both directly and indirectly via the subesophageal ganglion.  相似文献   

10.
With the number of satellite sensors and date centers being increased continuously, it is becoming a trend to manage and process massive remote sensing data from multiple distributed sources. However, the combination of multiple satellite data centers for massive remote sensing (RS) data collaborative processing still faces many challenges. In order to reduce the huge amounts of data migration and improve the efficiency of multi-datacenter collaborative process, this paper presents the infrastructures and services of the data management as well as workflow management for massive remote sensing data production. A dynamic data scheduling strategy was employed to reduce the duplication of data request and data processing. And by combining the remote sensing spatial metadata repositories and Gfarm grid file system, the unified management of the raw data, intermediate products and final products were achieved in the co-processing. In addition, multi-level task order repositories and workflow templates were used to construct the production workflow automatically. With the help of specific heuristic scheduling rules, the production tasks were executed quickly. Ultimately, the Multi-datacenter Collaborative Process System (MDCPS) were implemented for large-scale remote sensing data production based on the effective management of data and workflow. As a consequence, the performance of MDCPS in experiments environment showed that those strategies could significantly enhance the efficiency of co-processing across multiple data centers.  相似文献   

11.
Distribution of activity of mitochondrial oxidative enzyme cytochrome oxidase (CO) was studied in the thalamic (Ov) and telencephalic (field L) auditory centers of the pigeon Columbia livia. Different levels of CO activity are found in the core and belt of the centers: the high CO activity in the core of Ov (nCe) and telencephalic field L2 and the much lower or absent in the peripheral regions (Ovl, Ovm, SPO and L1 and L3). Comparison of our data with those of various avian and reptile species confirms the concept of the common plan of rostral auditory centers in sauropsid amniotes by the principle of the center-periphery (core-belt), which is characteristic of the corresponding mammalian centers. The separation of the central and peripheral parts of these centers is better pronounced in birds than in reptiles.  相似文献   

12.
Retinotopy and orientation columns in the monkey: A new model   总被引:2,自引:0,他引:2  
A model is presented in which orientation columns arise directly out of retinotopy. According to the model, iso-orientation lines are arrayed radially around nodal centers which correspond to cytochrome oxidase patches. The nodal centers form a square matrix superimposed upon the map of ocular dominance stripes. In the supragranular layers horizontal iso-orientation lines run down the centers of ocular dominance stripes, with vertical iso-orientation lines crossing perpendicularly. Diagonal orientations (45 degrees and 135 degrees) are represented as alternating iso-orientation zones at the centers of the interstices in the matrix (internodal centers). Preferred orientations in the infragranular layers are reversed with respect to the supragranular layers. The model is consistent with new data concerning ocularity and preferred orientation in systematic penetrations through striate cortex, and helps to explain some previously puzzling features of the relationship between ocular dominance columns, orientation columns and retinotopy.  相似文献   

13.
Heliobacteria and green sulfur bacteria have type I homodimeric reaction centers analogous to photosystem I. One remaining question regarding these homodimeric reaction centers is whether the structures and electron transfer reactions are truly symmetric or not. This question is relevant to the origin of the heterodimeric reaction centers, such as photosystem I and type II reaction centers. In this mini-review, Fourier transform infrared studies on the special pair bacteriochlorophylls, P798 in heliobacteria and P840 in green sulfur bacteria, are summarized. The data are reinterpreted in the light of the X-ray crystallographic structure of photosystem I and the sequence alignments of type I reaction center proteins, and discussed in terms of hydrogen bonding interactions and the symmetry of charge distribution over the dimer.  相似文献   

14.
An estimated 300,000 to 500,000 cases of type 1 diabetes exist today in the United States. Despite strict monitoring and attempts at control, people with type 1 diabetes still face the prospect of diminished health and earlier death than the general population. Islet transplantation offers an alternative to insulin usage and a potential treatment for type 1 diabetes mellitus. There are more than 30 islet transplant centers in the world focusing their efforts on the challenges and methods of this procedure. As the field of islet transplantation matures and the number of islet transplants performed increases, detailed analyses on factors that predict patient and graft survival are needed. This increased amount of data will allow for a better understanding of the safety and efficacy of islet transplantation. In response to the need for more complete information in the field, the National Institute of Diabetes and Digestive and Kidney Diseases is sponsoring the North American Collaborative Islet Transplant Registry (CITR). The mission of CITR is to expedite progress and promote safety in islet/β-cell transplantation through the collection, analysis, and communication of comprehensive and current data on all islet/β-cell transplants performed in North America. Compiling and analyzing data from all transplant centers in North America will accelerate the identification of both critical risk factors and key determinants of success, and thereby guide transplant centers in developing and refining islet/β-cell transplant protocols, leading to an advancement in the field of islet transplantation. Participation in CITR is voluntary, and more than 22 transplant centers have been invited to join. Seven centers are actively participating in CITR, with an additional 11 centers in the process of joining. Both an executive committee and a scientific advisory committee guide CITR. All islet transplants performed in North America since January 1, 1996, are captured by the CITR database. Through an electronic, Internet-based data capture system, quality control procedures, and minimization of duplicate efforts at the transplant center, the most relevant and succinct information are entered. From these data a comprehensive report will be published annually. In addition, special analyses will be performed and published periodically.  相似文献   

15.
Conditions for the incorporation of reaction centers, isolated from Rhodospirillum rubrum, into submitochondrial particles have been studied. Incorporation of the reaction centers into the lipid bilayer occurs in both orientations. Electron flow from the light activated reaction center to the b-c1 complex is demonstrated. Preliminary data on the reaction kinetics of the b cytochromes are given.  相似文献   

16.
The soluble (cytoplasmic plus periplasmic) Ni/Fe-S/Se-containing hydrogenase from Desulfovibrio baculatus (DSM 1743) was purified from cells grown in an 57Fe-enriched medium, and its iron-sulfur centers were extensively characterized by M?ssbauer and EPR spectroscopies. The data analysis excludes the presence of a [3Fe-4S] center, either in the native (as isolated) or in the hydrogen-reduced states. In the native state, the non-heme iron atoms are arranged as two diamagnetic [4Fe-4S]2+ centers. Upon reduction, these two centers exhibit distinct and unusual M?ssbauer spectroscopic parameters. The centers were found to have similar mid-point potentials (approximately -315 mV) as determined by oxidation-reduction titratins followed by EPR.  相似文献   

17.
Pierre Bennoun  Yung-sing Li 《BBA》1973,292(1):162-168
Simultaneous measurements of hydroxylamine photo-oxidation and fluorescence induction were performed in the presence of 3-(3,4-dichlorophenyl)-1,1-dimethylurea (DCMU). The results provide a justification for the common use of fluorescence data to estimate the concentration of active System II centers in the presence of inhibitors.The addition of DCMU to dark-adapted chloroplasts under special conditions induces a large increase of the initial yield of fluorescence. A reversible inactivation of part of the System II centers is responsible for this effect. Similar data were obtained with other classical inhibitors of oxygen evolution.  相似文献   

18.
The use of paramagnetic NMR data for the refinement of structures of proteins and protein complexes is widespread. However, the power of paramagnetism for protein assignment has not yet been fully exploited. PARAssign is software that uses pseudocontact shift data derived from several paramagnetic centers attached to the protein to obtain amide and methyl assignments. The ability of PARAssign to perform assignment when the positions of the paramagnetic centers are known and unknown is demonstrated. PARAssign has been tested using synthetic data for methyl assignment of a 47 kDa protein, and using both synthetic and experimental data for amide assignment of a 14 kDa protein. The complex fitting space involved in such an assignment procedure necessitates that good starting conditions are found, both regarding placement and strength of paramagnetic centers. These starting conditions are obtained through automated tensor placement and user-defined tensor parameters. The results presented herein demonstrate that PARAssign is able to successfully perform resonance assignment in large systems with a high degree of reliability. This software provides a method for obtaining the assignments of large systems, which may previously have been unassignable, by using 2D NMR spectral data and a known protein structure.  相似文献   

19.
Reaction centers from the carotenoidless mutant Rb. sphaeroides R26 were treated with sodium borohydride which is known to remove one of the accessory monomeric bacteriochlorophylls (BB). Subsequently, the carotenoid, spheroidene, was incorporated into the modified reaction centers. It is demonstrated by optical absorption and circular dichroism experiments that spheroidene, reconstituted into the sodium borohydride-treated Rb. sphaeroides R26 reaction centers, is bound in a single site, in the same environment and with the same structure as spheroidene reconstituted into untreated (native) Rb. sphaeroides R26 reaction centers. Transient optical and electron spin resonance spectroscopic data indicate that unless the accessory BB is present, the primary donor-to-carotenoid triplet energy transfer reaction is inhibited. These observations provide direct evidence for the involvement of the accessory BB in the triplet energy transfer pathway.  相似文献   

20.
Diversity of respiratory chain spectrophotometric assays may lead to difficult comparison of results between centers. The French network of mitochondrial diseases diagnostic centers undertook comparison of the results obtained with different protocols in the French diagnostic centers. The diversity of protocols was shown to have striking consequences, which prompted the network to undertake standardization and optimization of the protocols with respect to clinical diagnosis, i.e. high velocity while maintaining linear kinetics relative to time and enzyme concentration. Assays were set up on animal tissues and verified on control human muscle and fibroblasts.Influence of homogenization buffer and narrow range of optimal concentration of phosphate, substrate and tissue were shown. Experimental data and proposed protocols have been posted on a free access website. Their subsequent use in several diagnostic centers has improved consistency for all assays.  相似文献   

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