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1U.S. GEOLOGICAL SURVEY PROGRAMS AND INVESTIGATIONS RELATED TO SOIL AND WATER CONSERVATION显示文摘The U.S. Geological Survey has a rich tradition of collecting hydrologic data, especially for fluxes of water and suspended sediment, that provide a foundation for studies of soil and water conservation. Applied and basic research has included investigations of the effects of land use on rangelands, croplands, and forests; hazards mapping; derivation of flood and drought frequency, and other statistics related to streamflow and reservoir storage; development and application of models of rainfall-runoff relations, chemical quality, and sediment movement; and studies of the interactive processes of overland and channel flow with vegetation. Networks of streamgaging stations and (or) sampling sites within numerous drainage basins are yielding information that extends databases and enhances the ability to use those data for interpretive studies.W. R. OSTERKAMP and J. R. GRAY Research Hydrologist, U. S. Geological Survey, 1675 W. Anklam Road, Tucson, AZ 85745 U. S. A. Hydrologist, U. S. Geological Survey, 415 National Center, Reston, VA 20192 U. S. A. 2001International Journal of Sediment Research2001,16,3:22
2Hemoconcentration is a poor predictor of severity in acute pancreatitis显示文摘AIM: To determine whether the hematocrit (Hct) at admission or at 24 h after admission was associated with severe acute pancreatitis (AP), organ failure (OF), and pancreatic necrosis.METHODS: A total of 336 consecutive patients with a first AP episode were studied. Etiology, Hct values at admission and at 24 h, development of severe AP according to Atlanta's criteria, pancreatic necrosis, OF and mortality were recorded. Hemoconcentration was defined as Hct level >44% for males and >40% for females. The t-test and χ2 test were used to assess the association of hemoconcentration to the severity, necrosis and OF.Diagnostic accuracy was also determined.RESULTS: Biliary disease was the most frequent etiology(n = 148). Mean Hct levels at admission were 41±6%for females and 46±7% for males (P<0.01). Seventyeight (23%) patients had severe AP, and OF developed in 45 (13%) patients. According to contrast-enhanced computed tomography scan, 36% (54/150) patients showed pancreatic necrosis. Hct levels were elevated in58% (55/96) and 61% (33/54) patients with interstitial and necrotizing pancreatitis, respectively. Neither Hct levels at admission nor hemoconcentration at 24 h were associated with the severity, necrosis or OF. Sensitivity,specificity and positive predictive values for both determinations were very low; and negative predictive values were between 61% and 86%, being the highest value for OF.CONCLUSION: Hct is not a useful marker to predict a worse outcome in acute pancreatitis. In spite of the high negative predictive value of hemoconcentration, the prognosis gain is limited due to an already high incidence of mild disease.José M.Remes-Troche Andrés Duarte-Rojo Gustavo Morales Guillermo Robles-Díaz 2005World Journal of Gastroenterology2005,11,44:16
3FREDDY激光器的碎石效率的体外分析显示文摘背景和目的 双频双脉冲Nd :Yag(FREDDY)激光 (德国W .O .M .公司生产 )是一个短脉冲 ,双频率 ( 5 3 2nm和 10 64nm)的固体激光器。该激光器功率小 ,成本低 ,目前已在腔内碎石术中得到应用。我们设计了一个试验 ,以测试在不同能量和不同频率下的碎石效率。材料和方法 40个预先称过重量的硫酸钙石头被分成 4组 ,在 5Hz和 10Hz情况下 ,分别碎石 2min和 4min。一个水下的试验装置包括一个支架和一个容器 ,使得石英玻璃光纤可以直接抵住石头 ,发射激光。光纤被剥离成直径为 2 80 μm的裸露光纤 ,以保证最佳的能量传输。碎石完成后 ,所有的残余颗粒都落在容器内 ,晾干 48小时后 ,再重新称重 ,根据重量缺失的百分比来测试碎石效果。结果 5Hz时 ,碎石 2min的重量缺失为 2 4%;碎石 4min的重量缺失为 5 4%。 10Hz时 ,碎石 2min的情况与 5Hz时碎石 4min的结果相似 ,重量缺失为 5 1%;碎石 4min的重量缺失为 64 %,原先估计这么高的能量设置 ,重量缺失应该更大些。在高能量发射时 ,可以观察到光纤有损耗 ,这可能是导致碎石效率下降的原因。结论 FREDDY激光器在 5Hz时碎石 4min ,和在 10Hz时碎石 2min的效率是同等的 ,提示传输到结石的能量与碎石效率的相关性很好。而 10Hz、4min组的碎石效率比预期的略有下降 ,?Delvecchio FC Auge BK Brizuela RM Weizer AZ Zhong P Preminger GM 2004国外医学(泌尿系统分册)2004,24,4:10
4Primary liver cancer: Worldwide incidence and trends显示文摘F.Xavier Bosch Josepa Ribes Mireia Díaz Ramon Cléries 2004Gastroenterology2004,,5:10
5Changes in biodiversity and ecosystem function during the restoration of a tropical forest in south china显示文摘Tropical forests continue to vanish rapidly,but few long-term studies have ever examined if and how the lost forests can be restored.Based on a 45-year restoration study in south China,we found that a tropical rain forest,once completely destroyed,could not recover naturally without deliberate restoration efforts.We identified two kinds of thresholds that must be overcome with human ameliorative measures before the ecosystem was able to recover.The first threshold was imposed primarily by extreme physical conditions such as exceedingly high surface temperature and impoverished soil,while the second was characterized by a critical level of biodiversity and a landscape context that accommodates dispersal and colonization processes.Our three treatment catchments(un-restored barren land,single-species plantation,and mixed-forest stand)exhibited dramatically different changes in biodiversity and ecosystem functioning over 4 decades.The mixed forest,having the highest level of biodiversity and ecosystem functioning,possesses several major properties of tropical rain forest.These findings may have important implications for the restoration of many severely degraded or lost tropical forest ecosystems.REN Hai,LI ZhiAn,SHEN WeiJun,YU ZuoYue,PENG ShaoLin,LIAO ChongHui,DING MingMao & WU JianGuo 1 South China Botanical Garden,Chinese Academy of Sciences,Guangzhou 510650,China 2 Institute of Ecology and Evolution,Zhongshan University,Guangzhou 510275,China 3 Guangdong Institute of Entomology,Guangzhou 510275,China 4 School of Life Sciences and Global Institute of Sustainability,Arizona State University,Tempe,AZ 85287,USA 2007Science China(Life Sciences)2007,50,2:9
6Therapeutic options for HER-2 positive breast cancer: Perspectives and future directions显示文摘During the last 15 years we have witnessed an unprecedented expansion in the drugs developed to target human epidermal growth factor receptor-2(HER-2) positive breast cancer. Trastuzumab, pertuzumab, adotrastuzumab emtansine and lapatinib are currently food and drug administration(FDA)-approved for the treatment of breast cancer patients with HER-2 overexpressed. However, given the amount of information gathered from years of uninterrupted clinical research, it is essential to have periodic updates that succinctly recapitulate what we have learnt over these last years and help us to apply that information in our daily practice. This review will pursue that objective. We will summarize the most relevant and updated informationrelated to the state of the art management of HER-2 positive breast cancer in all the clinical scenarios including the adjuvant, neoadjuvant and metastatic settings. But we will also critically appraise that literature in order to highlight some key clinical concepts that should not be overlooked. Lastly, this review will also point out some of the most promising strategies that are currently being tested and may soon become available.Gonzalo Recondo Jr Enrique Dìaz Canton Màximo de la Vega Martin Greco Gonzalo Recondo Sr Matias E Valsecchi 2014World Journal of Clinical Oncology2014,5,3:7
7Recurrence of inflammatory pseudotumor in the distal bile duct: Lessons learned from a single case and reported cases显示文摘煽动性的 myofibroblastic 肿瘤(IMT ) 或煽动性的假肿瘤(IP ) 广泛地在文学被讨论了。他们通常在肺和上面的呼吸道被发现。然而,包含 biliopancreatic 区域的案例报导在最近的年增加了。限制到胰腺的头或远侧的胆汁管的这些损害的 Immunohistochemical 学习似乎与那些在称为自体免疫的胰腺炎的一个新实体观察了兼容,但是通常强烈的纤维变性反应(带状配列) 支配生产一个团。当这个条件限于胰腺的头时,胆总管可能被煽动性的过程包含,黄疸可以经常发生类似于胰的腺癌。我们以前报导了从与是一个极其稀罕的实体的自体免疫的胰腺炎联系的胆汁管产生的 IMT 的一个案例。在 Kaush-Whipple 切除术以后的四年,平淡的后续上的放射学的检查揭示了一个肿瘤团,建议本地复发。指导超声的 FNA 证实了我们的可疑诊断。作为其它,这个现在的案例建议坚持的后续是必要的以便在这个特定的地点阻止不可逆的肝损坏。EM López-Tomassetti Fernández H Díaz Luis A Martín Malagón I Arteaga González A Carrillo Pallarés 2006World Journal of Gastroenterology2006,12,24:7
8杜威的“三最”原则·“三R”准则显示文摘“三最”原则一八七六年,当美国图书馆协会在费城宣告成立时,著名的图书馆学专家麦尔维尔·杜威(Melvil Deway)在会上宣布了一个口号——“用最低的成本,以最好的书刊为最多的读者服务”(The best reading for Largest number at least cost)并把它作为图书馆的一条准则,我们把它简称为“三最”原则。看起来,“三最”AZ 1982图书馆学刊1982,4,3:6
9Stem cell therapy in the management of shoulder rotator cuff disorders显示文摘Rotator cuff tears are frequent shoulder problems that are usually dealt with surgical repair. Despite improved surgical techniques, the tendon-to-bone healing rate is unsatisfactory due to difficulties in restoring the delicate transitional tissue between bone and tendon. It is essential to understand the molecular mechanisms that determine this failure. The study of the molecular environment during embryogenesis and during normal healing after injury is key in devising strategies to get a successful repair. Mesenchymal stem cells(MSC) can differentiate into different mesodermal tissues and have a strong paracrine, anti-inflammatory, immunoregulatory and angiogenic potential. Stem cell therapy is thus a potentially effective therapy to enhance rotator cuff healing. Promising results have been reported with the use of autologous MSC of different origins in animal studies: they have shown to have better healing properties, increasing the amount of fibrocartilage formation and improving the orientation of fibrocartilage fibers with less immunologic response and reduced lymphocyte infiltration. All these changes lead to an increase in biomechanical strength. However, animal research is still inconclusive and more experimental studies are needed before human application. Future directions include expanded stem cell therapy in combination with growth factors or different scaffolds as well as new stem cell types and gene therapy.Maria Valencia Mora Miguel A Ruiz Ibán Jorge Díaz Heredia Raul Barco Laakso Ricardo Cuéllar Mariano García Arranz 2015World Journal of Stem Cells2015,7,4:6
10Using lysosomal membrane stability of haemocytes in Ruditapes philippinarum as a biomarker of cellular stress to assess contamination by caffeine, ibuprofen, carbamazepine and novobiocin显示文摘Although pharmaceuticals have beendetected in the environment only in the range from ng/L to μg/L, it has beendemonstrated that they can adversely affect the health status of aquatic organisms. Lysosomal membrane stability (LMS) has previously been applied as an indicator of cellularwell-being todetermine health status in bivalve mussels. The objective of this study is to evaluate LMS in Ruditapes philippinarum haemolymph using the neutral red retention assay (NRRA). Clamswere exposed in laboratory conditions to caffeine (0.1, 5, 15, 50 μg/L), ibuprofen (0.1, 5, 10, 50 μg/L), carbamazepine and novobiocin (both at 0.1, 1, 10, 50 μg/L) for35days. Results show adose-dependent effect of the pharmaceuticals. The neutral red retention time measured at the end of the bioassaywas significantly reduced by 50% after exposure to environmental concentrations (p < 0.05) (caffeine = 15 μg/L; ibuprofen = 10 μg/L; carbamazepine = 1 μg/L and novobiocin = 1 μg/L), compared to controls. Clams exposed to these pharmaceuticalswere considered to present adiminished health status (retention time <45 min), significantlyworse than controls (96 min) (p < 0.05). The predicted no environmental effect concentration (PNEC) results showed that these pharmaceuticals are very toxic at the environmental concentrations tested. Measurement of the alteration of LMS has been found to be a sensitive technique that enables evaluation of the health status of clams after exposure to pharmaceuticals under laboratory conditions, thus representing a robust Tier-1 screening biomarker.Gabriela V. Aguirre-Martínez Sara Buratti Elena Fabbri Angel T. DelValls M. Laura Martín-Díaz 2013Journal of Environmental Sciences2013,25,7:6
11Glutathione depleting drugs, antioxidants and intestinal calcium absorption显示文摘Glutathione(GSH) is a tripeptide that constitutes one of the main intracellular reducing compounds. The normal content of GSH in the intestine is essential to optimize the intestinal Ca2+ absorption. The use of GSH depleting drugs such as DL-buthionine-S,R-sulfoximine, menadione or vitamin K3, sodium deoxycholate or diets enriched in fructose, which induce several features of the metabolic syndrome, produce inhibition of the intestinal Ca2+ absorption. The GSH depleting drugs switch the redox state towards an oxidant condition provoking oxidative/nitrosative stress and inflammation, which lead to apoptosis and/or autophagy of the enterocytes. Either the transcellular Ca2+ transport or the paracellular Ca2+ route are altered by GSH depleting drugs. The gene and/or protein expression of transporters involved in the transcellular Ca2+ pathway are decreased. The flavonoids quercetin and naringin highly abrogate the inhibition of intestinal Ca2+ absorption, not only by restoration of the GSH levels in the intestine but also by their anti-apoptotic properties. Ursodeoxycholic acid, melatonin and glutamine also block the inhibition of Ca2+ transport caused by GSH depleting drugs. The use of any of these antioxidants to ameliorate the intestinal Ca2+ absorption under oxidant conditions associated with different pathologies in humans requires more investigation with regards to the safety, pharmacokinetics and pharmacodynamics of them.Luciana Moine María Rivoira Gabriela Díaz de Barboza Adriana Pérez Nori Tolosa de Talamoni 2018World Journal of Gastroenterology2018,24,44:5
12检测轮状病毒滴度的荧光灶法的改进显示文摘目的对检测轮状病毒滴度的荧光灶试验(FFA)方法进行改进。方法以FFA法检测轮状病毒滴度,并观察残留血清、病毒吸附量、甲基纤维素、离心以及Ca2+等因素对检测结果的影响,并验证改进后FFA的重复性。结果残留血清、病毒接种量、吸附后不洗涤、PBST洗板对FFA检测结果均无影响。而接种病毒后离心及不加甲基纤维素覆盖与对照组比较,差异有显著意义。用改进后方法对同批病毒进行18次试验,CV值为1.7%。结论改进后的方法具有操作简便、结果稳定、重复性好等优点。梁婧 徐葛林 黄晓媛 王继麟 孙文 夏飞 Kapikian AZ 杨晓明 2008中国生物制品学杂志2008,21,7:5
13Management of oligometastatic non-small cell lung cancer patients:Current controversies and future directions显示文摘Oligometastatic non-small cell lung cancer(NSCLC)describes an intermediate stage of NSCLC between localized and widely-disseminated disease.This stage of NSCLC is characterized by a limited number of metastases and a more indolent tumor biology.Currently,the management of oligometastatic NSCLC involves radical treatment(radiotherapy or surgery)that targets the metastatic lesions and the primary tumor to achieve disease control.This approach offers the potential to achieve prolonged survival in patients who,in the past,would have only received palliative measures.The optimal therapeutic strategies for the different scenarios of oligometastatic disease(intracranial vs extracranial disease,synchronous vs metachronous)remain undefined.Given the lack of head-to-head studies comparing radiotherapy to surgery in these patients,the decision to apply surgery or radiotherapy(with or without systemic treatment)must be based on prognostic factors that allow us to classify patients.This classification will allow us to select the most appropriate therapeutic strategy on an individualized basis.In the future,the molecular or microRNA profiles will likely improve the treatment selection process.The objective of the present article is to review the most relevant scientific evidence on the management of patients with oligometastatic NSCLC,focusing on the role of radiotherapy and surgery.We also discuss areas of controversy and future directions.Felipe Counago Javier Luna Luis Leonardo Guerrero Blanca Vaquero María Cecilia Guillén-Sacoto Teresa González-Merino Begona Taboada Verónica Díaz Belén Rubio-Viqueira Ana Aurora Díaz-Gavela Francisco JoséMarcos Elia del Cerro 2019World Journal of Clinical Oncology2019,10,10:5
14Use of a new retrograde filling material(Biodentine) for endodontic surgery: two case reports显示文摘Mineral trioxide aggregate(MTA) is considered at the present time as the gold standard for root-end filling in endodontic surgery.However, this biocompatible material presents several drawbacks such as a long setting time and handling difficulties. The aim of this article is to present a new commercialized calcium silicate-based material named Biodentine with physical improved properties compared to MTA in a clinical application. Two endodontic microsurgeries were performed by using specific armamentarium(microsurgical instrumentation, ultrasonic tips) under high-power magnification with an operatory microscope. Biodentine was used as a root-end filling in order to seal the root canal system. The two cases were considered completely healed at 1 year and were followed for one more year. The 2-year follow-up consolidated the previous observation with absence of clinical symptoms and radiographic evidence of regeneration of the periapical tissues.Grégory Caron Jean Azérad Marie-Odile Faure Pierre Machtou Yves Boucher 2014International Journal of Oral Science2014,6,4:5
15YKL40 expression in CD14^+ liver cells in acute and chronic injury显示文摘AIM:To demonstrate that CD14 + cells are an important source of the growth factor YKL40 in acute and chronic liver damage.METHODS:Rats were inoculated with one dose of CCl4 to induce acute damage.Liver biopsies were obtained at 0,6,12,24,48 and 72 h.For chronic damage,CCl4 was administered three days per week for 6 or 8 wk.Tissue samples were collected,and cellular populations were isolated by liver digestion and purified by cell sorting.YKL40 mRNA and protein expression were evaluated by realtime polymerase chain reaction and western blot.RESULTS:Acute liver damage induced a rapid increase of YKL40 mRNA beginning at 12 h.Expression peaked at 24 h,with a 26fold increase over basal levels.By 72 h however,YKL40 expression levels had nearly returned to control levels.On the other hand,chronic damage induced a sustained increase in YKL40 expression,with 7and 9fold higher levels at 6 and 8 wk,respectively.The pattern of YKL40 expression in different subpopulations showed that CD14+cells,which include Kupffer cells,are a source of YKL40 after acute damage at 72 h[0.09 relative expression units(REU)]as well as after chronic injury at 6 wk(0.11 REU).Hepatocytes,in turn,accounted for 0.06 and 0.01 REU after 72 h(acute)or 6 wk(chronic),respectively.The rest of the CD14cells(including T lymphocytes,B lymphocytes,natural killer and natural killer T cells) yielded 0.07 and 0.15 REU at 72 h and 6 wk,respectively.YKL40 protein expression in liver was detected at 72 h as well as 6 and 8 wk,with the highest expression relative to controls(11fold;P≤0.05)seen at 6 wk.Macrophages were stimulated by lipopolysaccharide.We demonstrate that under these conditions,these cells showed maximum expression of YKL40 at 12 h,with P<0.05 compared with controls.CONCLUSION:Hepatic CD14 + cells are an YKL40 mRNA and protein source in acute and chronic liver injury,with expression patterns similar to growth factors implicated in inflammationfibrogenesis.Oscar Pizano-Martínez Irinea Yaez-Sánchez Pilar Alatorre-Carranza Alejandra Miranda-Díaz Pablo C Ortiz-Lazareno Trinidad García-Iglesias Adrian Daneri-Navarro Mónica Vázquez-Del Mercado Mary Fafutis-Morris Vidal Delgado-Rizo 2011World Journal of Gastroenterology2011,17,33:3
16Tumor microenvironment involvement in colorectal cancer progression via Wnt/β-catenin pathway:Providing understanding of the complex mechanisms of chemoresistance显示文摘Colorectal cancer(CRC)continues to be one of the main causes of death from cancer because patients progress unfavorably due to resistance to current therapies.Dysregulation of the Wnt/β-catenin pathway plays a fundamental role in the genesis and progression of several types of cancer,including CRC.In many subtypes of CRC,hyperactivation of theβ-catenin pathway is associated with mutations of the adenomatous polyposis coli gene.However,it can also be associated with other causes.In recent years,studies of the tumor microenvironment(TME)have demonstrated its importance in the development and progression of CRC.In this tumor nest,several cell types,structures,and biomolecules interact with neoplastic cells to pave the way for the spread of the disease.Cross-communications between tumor cells and the TME are then established primarily through paracrine factors,which trigger the activation of numerous signaling pathways.Crucial advances in the field of oncology have been made in the last decade.This Minireview aims to actualize what is known about the central role of the Wnt/β-catenin pathway in CRC chemoresistance and aggressiveness,focusing on crosscommunication between CRC cells and the TME.Through this analysis,our main objective was to increase the understanding of this complex disease considering a more global context.Since many treatments for advanced CRC fail due to mechanisms involving chemoresistance,the data here exposed and analyzed are of great interest for the development of novel and effective therapies.María Belén Novoa Díaz María Julia Martín Claudia Gentili 2022World Journal of Gastroenterology2022,28,26:3
17Medical plant extracts and natural compounds with a hepatoprotective effect against damage caused by antitubercular drugs: A review显示文摘Drug-induced liver injury encompasses a spectrum of diseases ranging from mild biochemical abnormalities to acute liver failure; example of this scenery is hepatotoxicity caused by the first-line antituberculous drugs isoniazid, rifampin and pyrazinamide, which are basic for treatment of drug-sensible and drug-resistant tuberculosis. In the search for pharmacological alternatives to prevent liver damage, antitubercular drugs have been the subject of numerous studies and published reviews, a great majority of them carried out by Asian countries. At the same time, hepatoprotectors from plant source are now emerging as a possible alternative to counteract the toxic effects of these therapeutic agents. The present review aims to highlight the most recent studies on the subject, based information published in scientific databases such as Scopus and Pub Med.María Adelina Jiménez-Arellanes Gabriel Alfonso Gutiérrez-Rebolledo Mariana Meckes-Fischer Rosalba León-Díaz 2016Asian Pacific Journal of Tropical Medicine2016,9,12:3
18High prevalence of hepatic steatosis and vascular thrombosis in COVID-19:A systematic review and meta-analysis of autopsy data显示文摘BACKGROUND Coronavirus disease 2019(COVID-19)disease can frequently affect the liver.Data on hepatic histopathological findings in COVID-19 is scarce.AIM To characterize hepatic pathological findings in patients with COVID-19.METHODS We conducted a systematic review with meta-analysis registered on PROSPERO(CRD42020192813),following PRISMA guidelines.Eligible trials were those including patients of any age and COVID-19 diagnosis based on a molecular test.Histopathological reports from deceased COVID-19 patients undergoing autopsy or liver biopsy were reviewed.Articles including less than ten patients were excluded.Proportions were pooled using random-effects models.Q statistic and I2 were used to assess heterogeneity and levels of evidence,respectively.RESULTS We identified 18 studies from 7 countries;all were case reports and case series from autopsies.All the patients were over 15 years old,and 67.2%were male.We performed a meta-analysis of 5 studies,including 116 patients.Pooled prevalence estimates of liver histopathological findings were hepatic steatosis 55.1%[95%confidence interval(CI):46.2-63.8],congestion of hepatic sinuses 34.7%(95%CI:7.9-68.4),vascular thrombosis 29.4%(95%CI:0.4-87.2),fibrosis 20.5%(95%CI:0.6-57.9),Kupffer cell hyperplasia 13.5%(95%CI:0.6-54.3),portal inflammation 13.2%(95%CI:0.1-48.8),and lobular inflammation 11.6%(95%CI:0.3-35.7).We also identified the presence of venous outflow obstruction,phlebosclerosis of the portal vein,herniated portal vein,periportal abnormal vessels,hemophagocytosis,and necrosis.CONCLUSION We found a high prevalence of hepatic steatosis and vascular thrombosis as major histological liver features.Other frequent findings included portal and lobular inflammation and Kupffer cell hyperplasia or proliferation.Further studies are needed to establish the mechanisms and implications of these findings.Luis Antonio Díaz Francisco Idalsoaga Macarena Cannistra Roberto Candia Daniel Cabrera Francisco Barrera Alejandro Soza Rondell Graham Arnoldo Riquelme Marco Arrese Michael D Leise Juan Pablo Arab 2020World Journal of Gastroenterology2020,26,48:3
19Affinity-Based Network Interfaces for Efficient Communication on Multicore Architectures显示文摘Improving the network interface performance is needed by the demand of applications with high communication requirements (for example, some multimedia, real-time, and high-performance computing applications), and the availability of network links providing multiple gigabits per second bandwidths that could require many processor cycles for communication tasks. Multicore architectures, the current trend in the microprocessor development to cope with the difficulties to further increase clock frequencies and microarchitecture efficiencies, provide new opportunities to exploit the parallelism available in the nodes for designing efficient communication architectures. Nevertheless, although present OS network stacks include multiple threads that make it possible to execute network tasks concurrently in the kernel, the implementations of packet-based or connection-based parallelism are not trivial as they have to take into account issues related with the cost of synchronization in the access to shared resources and the efficient use of caches. Therefore, a common trend in many recent researches on this topic is to assign network interrupts and the corresponding protocol and network application processing to the same core, as with this affinity scheduling it would be possible to reduce the contention for shared resources and the cache misses. In this paper we propose and analyze several configurations to distribute the network interface among the different cores available in the server. These alternatives have been devised according to the affinity of the corresponding communication tasks with the location (proximity to the memories where the different data structures are stored) and characteristics of the processing core. As this approach uses several cores to accelerate the communication path of a given connection, it can be seen as complementary to those that consider several cores to simultaneously process packets belonging to either the same or different connections. Message passing interface (MPI) workloads and dynamic web servers have been considered as applications to evaluate and compare the communication performance of these alternatives. In our experiments, performed by full-system simulation, improvements of up to 35% in the throughput and up to 23% in the latency have been observed in MPI workloads, and up to 100% in the throughput, up to 500% in the response time, and up to 82% in the requests attended per second have been measured in dynamic web servers.Andrés Ortiz Julio Ortega Antonio F.Díaz Alberto Prieto 2013Journal of Computer Science & Technology2013,28,3:3
20Mapping aboveground biomass by integrating geospatial and forest inventory data through a k-nearest neighbor strategy in North Central Mexico显示文摘As climate change negotiations progress,monitoring biomass and carbon stocks is becoming an important part of the current forest research.Therefore,national governments are interested in developing forest-monitoring strategies using geospatial technology.Among statistical methods for mapping biomass,there is a nonparametric approach called k-nearest neighbor(kNN).We compared four variations of distance metrics of the kNN for the spatially-explicit estimation of aboveground biomass in a portion of the Mexican north border of the intertropical zone.Satellite derived,climatic,and topographic predictor variables were combined with the Mexican National Forest Inventory(NFI)data to accomplish the purpose.Performance of distance metrics applied into the kNN algorithm was evaluated using a cross validation leave-one-out technique.The results indicate that the Most Similar Neighbor(MSN)approach maximizes the correlation between predictor and response variables(r=0.9).Our results are in agreement with those reported in the literature.These findings confirm the predictive potential of the MSN approach for mapping forest variables at pixel level under the policy of Reducing Emission from Deforestation and Forest Degradation(REDD+).Carlos A AGUIRRE-SALADO Eduardo J TREVIO-GARZA Oscar A AGUIRRE-CALDERóN Javier JIMNEZ-PREZ Marco A GONZLEZ-TAGLE José R VALDZ-LAZALDE Guillermo SNCHEZ-DíAZ Reija HAAPANEN Alejandro I AGUIRRE-SALADO Liliana MIRANDA-ARAGóN 2014Journal of Arid Land2014,6,1:3
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