Academic literature on the topic 'Clusters'
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Journal articles on the topic "Clusters"
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Ahamad, Mohammed Gulam, Mohammed Faisal Ahmed, and Mohammed Yousuf Uddin. "Clustering as Data Mining Technique in Risk Factors Analysis of Diabetes, Hypertension and Obesity." European Journal of Engineering and Technology Research 1, no. 6 (July 27, 2018): 88–93. http://dx.doi.org/10.24018/ejeng.2016.1.6.202.
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This investigation explores data mining using open source software WEKA in health care application. The cluster analysis technique is utilized to study the effects of diabetes, obesity and hypertension from the database obtained from Virginia school of Medicine. The simple k-means cluster techniques are adopted to form ten clusters which are clearly discernible to distinguish the differences among the risk factors such as diabetes, obesity and hypertension. Cluster formation was tried by trial and error method and also kept the SSE as low as possible. The SSE is low when numbers of clusters are more. Less than ten clusters formation unable to yield distinguishable information. In this work each cluster is revealing quit important information about the diabetes, obesity, hypertension and their interrelation. Cluster 0: Diabetes ? Obesity ? Hypertension = Healthy patient, Cluster 1: Diabetes ? Obesity ? Hypertension = Healthy patient, Cluster2: Diabetes ? Obesity ? Hypertension = Obesity, Cluster3: Diabetes ? Obesity ? Hypertension = Patients with Obesity and Hypertension, Cluster4: Boarder line Diabetes ? Obesity ? Hypertension = Sever obesity, Cluster5: Obesity ? Hyper tension ? Diabetes = Hypertension, Cluster6: Border line obese ? Border line hypertension ? Diabetes = No serious complications, Cluster 7: Obesity ? Hypertension ? Diabetes= Healthy patients, Cluster 8: Obesity ? Hypertension ? Diabetes= Healthy patients, and Cluster 9: Diabetes ? Hyper tension ? Obesity = High risk unhealthy patients.
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Lee, Chang Hyung, and Douglas G. Steigerwald. "Inference for Clustered Data." Stata Journal: Promoting communications on statistics and Stata 18, no. 2 (June 2018): 447–60. http://dx.doi.org/10.1177/1536867x1801800210.
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In this article, we introduce clusteff, a community-contributed command for checking the severity of cluster heterogeneity in cluster–robust analyses. Cluster heterogeneity can cause a size distortion leading to underrejection of the null hypothesis. Carter, Schnepel, and Steigerwald (2017, Review of Economics and Statistics 99: 698–709) develop the effective number of clusters to reflect a reduction in the degrees of freedom, thereby mirroring the distortion caused by assuming homogeneous clusters. clusteff generates the effective number of clusters. We provide a decision tree for cluster–robust analysis, demonstrate the use of clusteff, and recommend methods to minimize the size distortion.
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Ye, Di, Yenchun Jim Wu, and Mark Goh. "Hub firm transformation and industry cluster upgrading: innovation network perspective." Management Decision 58, no. 7 (March 26, 2020): 1425–48. http://dx.doi.org/10.1108/md-12-2017-1266.
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PurposeThis research paper examines how hub firm transformation and restructuring of network partnerships shape the development of industrial clusters in China.Design/methodology/approachQuestionnaire data were collected from 210 managers (response rate 70.9 percent) from the manufacturing industrial clusters in Eastern China.FindingsThe results inform that a cluster’s hub firm transformation influences the evolution of the cluster. Though the hub firm may possess transformation capabilities, the cluster is likely to be weakened if network partnerships and resource synergy are not formed amongst the cluster members.Research limitations/implicationsThis paper, in examining the individual- and firm-level attributes of orchestration capability and their interactions, sheds light on the firm level and inter-firm level relationships between resources and innovation in an industrial cluster.Practical implicationsTo facilitate learning and the upgrading of firms within an industry cluster and promote a cluster’s innovation network, policymakers can initiate preferential policy measures to cultivate support to strategically transform a cluster’s hub firm, thus fostering cluster network growth.Originality/valueThe paper studies the evolution of clusters by investigating the hub firm transformation and member firm interaction. Focusing on the inter-firm network interactions lends a richer understanding of the nuances of the evolution of industrial clusters in Asia.
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Razminiene, Kristina. "Circular economy in clusters' performance evaluation." Equilibrium 14, no. 3 (September 30, 2019): 537–59. http://dx.doi.org/10.24136/eq.2019.026.
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Research background: The value of clusters in developing advanced technology products and services as well as promoting regional growth is acknowledged by many policymakers and researchers (Lee et al., 2012). Hence, clusters are identified as enablers of the circular economy and resource efficiency in this study. Companies aim to enhance competencies and create competitive advantages in global competition and this can be achieved through pulling from a common and accessible pool of resources, information and demand for innovation which means that companies can profit from belonging to a cluster.
Purpose of the article: The main aim of the article is to overview the scientific literature that addresses the circular economy, identify clusters and their role in the circular economy and suggest how small and medium enterprises could engage in a circular economy through clusters' performance development.
Methods: Bibliometric literature analysis enables identifying the latest trends in scientific articles regarding a circular economy and clusters. The analytical hierarchy process (AHP) allows for composing the scheme of the cluster’s competitive advantage within circular economy.
Findings & Value added: The findings suggest that resource efficiency is considered to be one of the most important ambitions and clusters can work as enablers of a circular economy for small and medium enterprises (SMEs), gaining a competitive advantage at the same time. Clusters can encourage and provide conditions in which SMEs would turn to a circular economy. The scheme of Cluster's competitive advantage proposed by the author can help cluster's coordinators, policymakers and all the concerned parties to verify the importance of clusters' involvement in the circular economy.
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Altomare, Michele, Andrea Chierici, Francesco Virdis, Andrea Spota, Stefano Piero Bernardo Cioffi, Shir Sara Bekhor, Luca Del Prete, et al. "Centralization of Major Trauma Influences Liver Availability for Transplantation in Northern Italy: Lesson Learned from COVID-19 Pandemic." Journal of Clinical Medicine 11, no. 13 (June 24, 2022): 3658. http://dx.doi.org/10.3390/jcm11133658.
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Background: During the COVID-19 pandemic, the centralization of patients allowed trauma and transplants referral centers to continue their routine activity, ensuring the best access to health care. This study aims to analyze how the centralization of trauma is linked with liver allocation in Northern Italy. Methods: Cluster analysis was performed to generate patient phenotype according to trauma-related variables. Comparison between clusters was performed to evaluate differences in damage control strategy procedures (DCS) performed and the 30-day graft dysfunction. Results: During the pandemic period, the centralization of major trauma has deeply impaired the liver procurement and allocation between the transplant centers in the metropolitan area of Milan (Niguarda: 22 liver procurement; other transplant centers: 2 organ procurement). Two clusters were identified the in Niguarda’s series: cluster 1 is represented by 17 (27.4%) trauma donors, of which 13 (76.5%) were treated with DCS procedures, and 4 (23.5%) did not; cluster 2 is represented by 45 trauma donors (72.6%), of which 22 (48.8%) underwent DCS procedures. A significant difference was found in the number of DCS procedures performed between clusters (3.18 ± 2.255 vs. 1.11 ± 1.05, p = 0.0001). Comparative analysis did not significantly differ in the number of transplanted livers (cluster1/cluster2 94.1%/95.6% p = 0.84) and the 30-day graft dysfunction rate (cluster1/cluster2 0.0%/4.8% p = 0.34). Conclusions: The high level of care guaranteed by first-level trauma centers could reduce the loss of organs suitable for donation, maintaining the good outcomes of transplanted ones, even in case of multiple organ injuries. The pandemic period underlined that the centralization of major trauma impairs the liver allocation between transplant centers.
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Rines, Kenneth J., and Margaret J. Geller. "Redshift Survey of 12 Moderate-redshift Clusters." Research Notes of the AAS 6, no. 12 (December 22, 2022): 277. http://dx.doi.org/10.3847/2515-5172/acad05.
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Abstract We conducted a redshift survey of 12 X-ray selected clusters in the redshift range z = 0.35–0.50 with MMT/Hectospec. The redshift surveys confirm that these clusters are massive systems. There are no massive groups or clusters projected along the line of sight that might contaminate the observed cluster X-ray properties significantly. We identify 25–79 members per cluster and refine the estimates of each cluster’s mean redshift. We include the 8004 new redshifts in Data Behind the Figure.
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Tri Gustiane, Indri, Martanto Martanto, and Tati Suprapti. "CLUSTERING HASIL CEK DARAH DIABETES LANSIA MENGGUNAKAN METODE K-MEANS DI POSBINDU KP. LEBAKJERO DESA CIHERANG." JATI (Jurnal Mahasiswa Teknik Informatika) 8, no. 2 (April 24, 2024): 2125–29. http://dx.doi.org/10.36040/jati.v8i2.9281.
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Penelitian ini bertujuan untuk menganalisis hasil cek darah lansia yang menderita diabetes menggunakan metode K-Means. Diabetes adalah penyakit metabolic yang ditandai dengan tingginya kadar gula darah (hiperglikemia) yang disebabkan oleh kekurangan insulin atau tidak efektif insulin dalam mengatur metabolisme glukosa. Selain itu terdapat faktor-faktor lain menjadi penyebab terjadinya diabetes diantaranya seperti faktor keturunan, berat badan, usia, tekanan darah dan sebagainya. Diabetes penyakit kronis yang umumnya terjadi pada lansia dan membutuhkan pemantauan berkala untuk mengelola kondisi mereka. Dengan metode K-Means untuk mengelompokan lansia ke dalam kategori yang berbeda berdasarkan karakteristik darah mereka. Metode K-Means Clustering merupakan metode yang digunakan dalam data mining yang cara kerjanya mencari dan mengelompokan data yang mempunyai kemiripan karakteristik antara data satu dengan data lain yang telah diperol eh data yang memiliki kesamaan bukan data yang sama tetapi memiliki karakteristik yang sama, Dengan menerapkan metode K-Means Clustering dapat membantu pihak Posbindu Kp.Lebakjero Desa Ciherang. Penelitian ini akan di cluster menjadi Lansia yang memiliki penyakit Diabetes paling tinggi di Posbindu Kp.Lebakjero Desa Ciherang. Dalam Cluster tersebut atribut yang dipakai adalah Nama, Jenis Kelamin, Usia, dan Hasil Cek Darah. Hasil analisis dapat membantu petugas kesehatan dalam merancang intervensi yang lebih spesifik dan efektif untuk mengelola diabetes pada populasi lansia. Hasil penelitian K-Means Clustering dibantu hasil nilai DBI dengan -0.597, menjadi 6 cluster dimana hasil cluster0 57, cluster1 24, cluster2 30, cluster3 23, cluster4 44, cluster5 25 dan hasil paling optimal di cluster0 yaitu 57. Cluster0 dengan 57 lansia dimana hasil cluster adalah kp.lebakjero mempunyai lansia paling banyak dan mempunyai diabetes paling tinggi. Selain itu, penelitian ini juga untuk mencapai sesuatu hasil yang akurat terhadap data yang di hasilkan di Posbindu Kp.Lebakjero Desa Ciherang.
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Ruomu, Li, Vincent Yip, and Paweł Dobrzański. "Clusters – Typology and Public Policy." Prace Naukowe Uniwersytetu Ekonomicznego we Wrocławiu 67, no. 3 (2023): 38–51. http://dx.doi.org/10.15611/pn.2023.3.05.
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Clusters, especially high-tech, are important economic phenomena in modern society. As the archetype, Silicon Valley drives governments over the world to initiate their own cluster. Likewise, the cluster policy has also become a major policy tool in the urban planning field. Based on approaches to initiate and promote clusters, the current cluster policy can be divided into three models, the American model, the Asian model, and the European one. This paper focuses on the sustainability of clusters, reviews the literature about high-tech clusters, cluster policy, and the developments of selected clusters, including Silicon Valley, Silicon Fen, Hsinchu Science Park, Singapore Science Park and One-North, and Akademgorodok; discusses their developments and challenges, and aims to explore the role of government and possible approaches. Based on the data analysis, the research concluded that governments are essential to a cluster’s sustainability. The approach of mixing bottom-up and top-down intervention might be the final direction for all countries, and the only difference lies in timing, which varies with local resources, social environments, and especially culture. For governments, its role should be identifying the right timing to implement the adaption in policy, coordinate, and lead the battle for sustainability in practice.
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Godara, Poonam, Shrawan Kumar, and Darvinder Kumar. "Evaluation of Genetic Variation in Indian mustard (Brassica Juncea L Czern and Coss) Using Multivariate Techniques." Journal of Agriculture Research and Technology 47, no. 03 (2022): 344–48. http://dx.doi.org/10.56228/jart.2022.47315.
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A set of 310 lines of Indian mustard (Brassica juncea L Czern and Coss) were analysed for cluster and principal component analysis (PCA). PCA identified four principal components which explained 65.13% of total variability among the 310 genotypes. Hierarchical cluster analysis grouped 310 genotypes into 3 clusters. Cluster1 included maximum number of 155 genotypes and clusters 3 had the lowest number of 43 genotypes. The grouping pattern of genotypes obtained by cluster analysis and PCA plots was almost similar.
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Akter, F., MZ Islam, A. Akter, SK Debsharma, A. Shama, and M. Khatun. "Genetic Diversity of Bacterial Blight Resistant Rice (Oryza sativa L.) Genotypes from INGER." Bangladesh Rice Journal 23, no. 2 (July 17, 2020): 59–64. http://dx.doi.org/10.3329/brj.v23i2.48248.
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Genetic diversity of 65 rice genotypes was studied from IRBBN (International Rice Bacterial Blight Nursery) of INGER (International Network for Genetic Evaluation of Rice) materials through Mahalanobis D2 statistic for grain yield and yield contributing characters. The genotypes were grouped into five clusters. The inter-cluster distances were higher than intra-cluster distances indicating wider genetic diversity among the genotypes of different clusters. The intra-cluster distances were lower in all the cases reflecting homogeneity of the genotypes within the clusters. The cluster III contained the highest number of genotypes (23) and the clusterv contained the lowest (8). The highest intra-cluster distance was noticed for the cluster I and lowest for cluster III. The highest inter-cluster distance was observed between cluster I and V, followed by cluster IV and V, cluster II andV and the lowest between cluster I and IV. Regarding inter-cluster distance, the genotypes of cluster V showed high genetic distance from all other clusters. The genotypes from cluster V could be hybridized with the genotypes of other clusters for producing transgressive segregants. Based on canonical vector analysis, panicle number per plant had maximum contribution towards genetic divergence. The highest cluster means for yield, grain/panicle and spikelet fertility were obtained from cluster V. The highest means for 1000 grain weight, second higher yield and the lowest growth duration were found in cluster II, while the lowest mean value for yield and 1000 grain weight and higher mean value for growth duration were found in cluster IV. The crosses between the genotypes/parents of cluster V and cluster II, cluster V and cluster I would exhibit high heterosis as well as higher level of yield potential. Therefore, more emphasis should be given for selection of the genotypes from clusters II and V for future breeding programme.
Bangladesh Rice j. 2019, 23(2): 59-64
Dissertations / Theses on the topic "Clusters"
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Jeltema, Tesla Erin. "Cosmology with clusters of galaxies : high-redshift clusters and the evolution of cluster substructure." Thesis, Massachusetts Institute of Technology, 2004. http://hdl.handle.net/1721.1/28372.
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Thesis (Ph. D.)--Massachusetts Institute of Technology, Dept. of Physics, 2004.Includes bibliographical references (p. 85).
Clusters of galaxies have become an important cosmological tool, yet we do not un-erstand many aspects of their formation and development. In this thesis, I pursue two projects aimed at using clusters to constrain cosmology and better understanding cluster evolution. First, I examine the Chandra observation of MS1054-0321. MS1054-0321 is the highest redshift cluster in the Einstein Medium Sensitivity Survey (EMSS), and it was one of the first high-redshift clusters observed with Chandra. I confirm that this cluster is hot and massive, although its temperature is slightly lower than inferred previously. I also detected an iron line in this cluster, one of the first detections of iron in a cluster at these redshifts, with an abundance consistent with early enrichment of the ICM. MS1054-0321 exhibits significant substructure, which I study in detail for the first time. In X-rays, it appears to be a nearly equal mass double cluster in the process of merging. Both the cluster galaxies and mass associated with the western subclump are offset from the X-ray peak, possibly indicating that the gas in the subclump is being stripped off as it falls into the cluster. Despite the lower temperature, I find that the detection of this cluster in the EMSS constrains Qm to be less than one.
(cont.) In the second project, I investigate the evolution of cluster substructure with redshift, quantifying for the first time cluster structure out to z [approx.] 1. My sample includes 40 X-ray selected, luminous clusters from the Chandra archive, and I quantify cluster morphology using the power ratio method (Buote & Tsai 1995). I find that, as expected qualitatively from hierarchical models of structure formation, high-redshift clusters have more substructure and are dynamically more active than low-redshift clusters. Specifically, the clusters with z > 0.5 have significantly higher average third and fourth order power ratios than the lower redshift clusters. This observation of structure evolution indicates that dynamical state may be an important systematic effect in cluster studies seeking to constrain cosmology, and when calibrated against numerical simulations, structure evolution will itself provide interesting bounds on cosmological models.
by Tesla Erin Jeltema.
Ph.D.
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Junior, Paulo Vanderlei Cassanego. "Governança em clusters de negócios: um estudo em clusters do Rio Grande do Sul." Universidade de São Paulo, 2014. http://www.teses.usp.br/teses/disponiveis/12/12139/tde-06012015-120214/.
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Esta tese teve como objetivo apresentar quais os elementos que devem constar em um modelo descritivo para representar o que ocorre na realidade na governança em clusters. Para atingir este objetivo desenvolveu-se uma pesquisa para compreender que elementos eram considerados por pesquisadores ao escreveram sobre a governança de aglomerados produtivos. De posse destes dados, o material resultante foi classificado considerando sua natureza. Se descritivos ou normativos. Assim foram constituídos os Elementos da Governança em Cluster com sua conceituação a partir do que indica a literatura da área. Os Elementos da Governança, a saber: Estrutura da Governança, Funções da Governança, Mecanismos /Meios da Governança, Objetivos da Governança, Agentes da Governança e Requisitos da governança. Após, para atingir o objetivo da Tese, fez-se necessária a confrontação das informações teóricas com dados empíricos. Então se desenvolveu pesquisa em 5 Clusters no Estado Rio Grande do Sul. Foram estudados os seguintes casos: Cluster de Doces, na região de Pelotas-RS; Cluster Bovinocultura de Corte, na região da Campanha Gaúcha; Cluster Vitivinícola, na Região da Fronteira Oeste de Campanha; Cluster Moveleiro, na Região Central do Estado; e Cluster Metal-Mecânico. Na Serra Gaúcha. Os dados coletados constituíram-se em um modelo descritivo visando representar como estão apresentados os Elementos da Governança na realidade. A Estrutura da Governança foi definida como a forma como se organiza a governança em um cluster. De forma hierárquica ou heterárquica, apresentando firmas independentes que operam como uma entidade única. A Função da Governança foi definida como o ato de influenciar a tomada de decisão das empresas no aglomerado, indicando formas de interação entre as organizações. Os Mecanismos da Governança foram definidos como contratos formais e informais que organizam o relacionamento entre organizações em um cluster. O Objetivo da Governança foi definido como Garantir vitalidade do agrupamento compondo competitividade e maximização do valor para toda a cadeia de produção. Os Agentes da Governança foram definidos como empresas independentes, ligadas por vínculos de proximidade geográfica, relacionamento transacional, processos competitivos e/ou cooperativos, governo local, instituições científicas e de apoio. Como requisito para a existência de Governança foi definido que a confiança é o principal atributo.This thesis aims to show what elements should be included in a descriptive model to represent what actually occurs in governance in clusters. To achieve this goal developed a survey to understand what factors were considered by the researchers wrote about the governance of production clusters. Using these data, the resulting material was classified considering their nature. If descriptive or normative. Thus were formed the Elements of Governance Cluster with its concept from the literature would suggest the area. Elements of Governance, namely: Governance Structure, Functions Governance Mechanisms / Media Governance, Governance Goals, Agents and Governance Requirements governance. After, to achieve the objective of the thesis, it was necessary to confrontation of theoretical information with empirical data. Then developed in 5 research clusters in Rio Grande do Sul state the following cases were studied: Cluster Candy, in the region of Pelotas; Cluster Beef Cattle in the Campanha Gaucha region; Wine Cluster in the Border Campaign West Region; Cluster Furniture in the State Central Region; Cluster and Metal-mechanic. In the Serra Gaucha. The data collected consisted of a descriptive model, to represent how the elements are shown Governance in reality. The Structure of Governance was defined as how governance is organized in a cluster. Hierarchical or heterarchical form, with independent firms that operate as a single entity. The Role of Governance has been defined as the act of influencing the decision making of firms in the cluster, indicating ways of interaction between organizations. The Mechanisms of Governance were defined as formal and informal contracts that organize the relationship between organizations in a cluster. The Purpose of the Governance was set to ensure the vitality and competitiveness cluster composing maximizing value for the whole chain of production. Agents of the Governance were defined as independent companies linked by bonds of geographical proximity, transactional relationships, competitive and / or cooperative processes, local government, scientific institutions and support. As a requirement for the existence of Governance has been defined that trust is the main attribute.
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Contini, Emanuele. "Galaxy populations in clusters and proto-clusters." Doctoral thesis, Università degli studi di Trieste, 2014. http://hdl.handle.net/10077/9964.
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2012/2013The aim of my Thesis is to explore the physical properties of the galaxy population in clusters and proto-clusters. A large number of physical processes plays an important role in the formation and evolution of galaxies: cooling, that allows the condensation of gas in the centre of dark matter haloes; star formation, that converts cold gas in stars; feedback from Active Galactic Nuclei (AGN), that prevents the gas in the central regions of haloes from "over-cooling"; feedback from Supernovae, which liberates energy in the surrounding, mixing the gas and enriching it with heavy metals. Galaxy clusters are special environments in which additional important processes take place, and play an important role in the evolution of the cluster galaxy population. Galaxy merging, harassments, tidal interactions, ram pressure stripping and strangulation are all processes acting in dense environments such as clusters of galaxies. I will take advantage of a {\it state of the art}-semi-analytic model of galaxy formation and of a set of 27 high-resolution dark matter only simulations: the semi-analytic model is based on physically motivated and observationally constrained prescriptions for the physical processes listed above and makes use of merger-trees extracted from the simulations to generate mock catalogues of galaxies. First, I make use of this set of simulations to carry out a statistical study of dark matter substructures. In the framework of modern theories of galaxy formation, dark matter substructures can be considered as the birth-sites of luminous galaxies. Therefore, the analysis of subhaloes, and in particular of their mass and spatial distributions, merger and mass accretion histories, provides important information about the expected properties of galaxies in the framework of hierarchical galaxy formation models. I have studied the amount and distribution of dark matter substructures within dark matter haloes, focusing mainly on the measured properties of subhaloes as a function of the mass and physical properties of their parent haloes, and redshift. I show that the fraction of halo mass in substructures increases with increasing mass, reaching $10 \%$ for haloes with mass of the order of $10^{15} \,M_{\odot} \hm$. The scatter in the relation is driven by halo concentration, with less concentrated haloes having larger fractions of mass in substructures. Most of this mass is locateted in the external regions of the parent haloes, in relatively few, but massive subhaloes, thus giving rise to a mass segregation which appears to be stronger at increasing redshift. Tidal stripping is found to be the process responsible for that. In fact, haloes that are more massive at the time of accretion, and that are supposed to host more luminous galaxies, are brought closer to the centre on shorter time-scales by dynamical friction, and therefore suffer of a more significant stripping. The results confirm that the main properties of galaxies, such as luminosity or stellar mass, are related to the mass of subhalos at infall, as found in previous studies.. The main results discussed in this part of the Thesis have been published in Contini et al. (2012), MNRAS.420.2978C. In a second part, I describe the implementation of physical processes responsible for the generation of the Intra-Cluster Light (ICL) in the available semi-analytic model, that, in its original form, does not account for them. The inclusion of these physical processes is, thus, an important improvement of the model. I take advantage of this upgrade of the model to investigate the origin of the ICL and to understand how the main properties of galaxies change with respect to a model that does not include these additional prescriptions. I find the fraction of ICL in groups and clusters predicted by the model to range between $10 \%$ and $40 \%$, with a large scatter and no halo mass dependence. Large part of the scatter on cluster scales is due to a range of dynamical histories, while on smaller scales it is mainly driven by individual accretion events and stripping of relatively massive satellites, with mass of the order of $10^{10.5} \, M_{\odot} \hm$, found to be the major contributors to the ICL. The ICL forms very late, below $ z \sim 1$ and a non negligible fraction (between $5 \%$ and $25 \%$) has been accreted during the hierarchical growth of haloes. Moreover, the ICL is made of stars which cover a relatively large range of metallicity, with the bulk of them being sub-solar, in agreement with recent observational data. The main results of this analysis have been submitted to MNRAS (Contini et al. 2013). In the last part of the thesis, the updated model is used to investigate the properties of the galaxy population in proto-cluster regions. The work is still in progress. I am testing the predictions of the semi-analytic model and comparing them with observations in terms of properties such as galaxy colours, star formation and stellar mass. A preliminary analysis of one very massive proto-cluster region shows that the galaxy population gets red and tend to cluster around the most massive galaxy as time goes by. There are, in literature, only a few attempts to probe such peculiar regions of the Universe from a theoretical point of view. The novelty of this work lies in the connection between massive clusters observed in the local Universe and the proto-cluster regions from which they have formed. I will try to define what a proto-cluster region is, and how it looks like, by studying the main properties of progenitors it contains. Specifically, I will investigate the spatial and velocity distributions of galaxies in simulated proto-clusters, looking at the red and blue galaxy distributions in these regions, as well as at BCG and satellite properties as a function of redshift. The main results of this work will be the subject of a paper in preparation.
XXV Ciclo
1982
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Kozovska, Kornelia <1981>. "Business Clusters in Eastern Europe: Policy Analysis and Cluster Performance." Doctoral thesis, Alma Mater Studiorum - Università di Bologna, 2009. http://amsdottorato.unibo.it/1611/2/Tesi_Kornelia_Kozovska.pdf.
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Clusters have increasingly become an essential part of policy discourses at all levels, EU, national, regional, dealing with regional development, competitiveness, innovation, entrepreneurship, SMEs. These impressive efforts in promoting the concept of clusters on the policy-making arena have been accompanied by much less academic and scientific research work investigating the actual economic performance of firms in clusters, the design and execution of cluster policies and going beyond singular case studies to a more methodologically integrated and comparative approach to the study of clusters and their real-world impact. The theoretical background is far from being consolidated and there is a variety of methodologies and approaches for studying and interpreting this phenomenon while at the same time little comparability among studies on actual cluster performances. The conceptual framework of clustering suggests that they affect performance but theory makes little prediction as to the ultimate distribution of the value being created by clusters. This thesis takes the case of Eastern European countries for two reasons. One is that clusters, as coopetitive environments, are a new phenomenon as the previous centrally-based system did not allow for such types of firm organizations. The other is that, as new EU member states, they have been subject to the increased popularization of the cluster policy approach by the European Commission, especially in the framework of the National Reform Programmes related to the Lisbon objectives. The originality of the work lays in the fact that starting from an overview of theoretical contributions on clustering, it offers a comparative empirical study of clusters in transition countries. There have been very few examples in the literature that attempt to examine cluster performance in a comparative cross-country perspective. It adds to this an analysis of cluster policies and their implementation or lack of such as a way to analyse the way the cluster concept has been introduced to transition economies.
Our findings show that the implementation of cluster policies does vary across countries with some countries which have embraced it more than others. The specific modes of implementation, however, are very similar, based mostly on soft measures such as funding for cluster initiatives, usually directed towards the creation of cluster management structures or cluster facilitators. They are essentially founded on a common assumption that the added values of clusters is in the creation of linkages among firms, human capital, skills and knowledge at the local level, most often perceived as the regional level. Often times geographical proximity is not a necessary element in the application process and cluster application are very similar to network membership. Cluster mapping is rarely a factor in the selection of cluster initiatives for funding and the relative question about critical mass and expected outcomes is not considered. In fact, monitoring and evaluation are not elements of the cluster policy cycle which have received a lot of attention. Bulgaria and the Czech Republic are the countries which have implemented cluster policies most decisively, Hungary and Poland have made significant efforts, while Slovakia and Romania have only sporadically and not systematically used cluster initiatives.
When examining whether, in fact, firms located within regional clusters perform better and are more efficient than similar firms outside clusters, we do find positive results across countries and across sectors. The only country with negative impact from being located in a cluster is the Czech Republic.
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Kozovska, Kornelia <1981>. "Business Clusters in Eastern Europe: Policy Analysis and Cluster Performance." Doctoral thesis, Alma Mater Studiorum - Università di Bologna, 2009. http://amsdottorato.unibo.it/1611/.
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Clusters have increasingly become an essential part of policy discourses at all levels, EU, national, regional, dealing with regional development, competitiveness, innovation, entrepreneurship, SMEs. These impressive efforts in promoting the concept of clusters on the policy-making arena have been accompanied by much less academic and scientific research work investigating the actual economic performance of firms in clusters, the design and execution of cluster policies and going beyond singular case studies to a more methodologically integrated and comparative approach to the study of clusters and their real-world impact. The theoretical background is far from being consolidated and there is a variety of methodologies and approaches for studying and interpreting this phenomenon while at the same time little comparability among studies on actual cluster performances. The conceptual framework of clustering suggests that they affect performance but theory makes little prediction as to the ultimate distribution of the value being created by clusters. This thesis takes the case of Eastern European countries for two reasons. One is that clusters, as coopetitive environments, are a new phenomenon as the previous centrally-based system did not allow for such types of firm organizations. The other is that, as new EU member states, they have been subject to the increased popularization of the cluster policy approach by the European Commission, especially in the framework of the National Reform Programmes related to the Lisbon objectives. The originality of the work lays in the fact that starting from an overview of theoretical contributions on clustering, it offers a comparative empirical study of clusters in transition countries. There have been very few examples in the literature that attempt to examine cluster performance in a comparative cross-country perspective. It adds to this an analysis of cluster policies and their implementation or lack of such as a way to analyse the way the cluster concept has been introduced to transition economies.
Our findings show that the implementation of cluster policies does vary across countries with some countries which have embraced it more than others. The specific modes of implementation, however, are very similar, based mostly on soft measures such as funding for cluster initiatives, usually directed towards the creation of cluster management structures or cluster facilitators. They are essentially founded on a common assumption that the added values of clusters is in the creation of linkages among firms, human capital, skills and knowledge at the local level, most often perceived as the regional level. Often times geographical proximity is not a necessary element in the application process and cluster application are very similar to network membership. Cluster mapping is rarely a factor in the selection of cluster initiatives for funding and the relative question about critical mass and expected outcomes is not considered. In fact, monitoring and evaluation are not elements of the cluster policy cycle which have received a lot of attention. Bulgaria and the Czech Republic are the countries which have implemented cluster policies most decisively, Hungary and Poland have made significant efforts, while Slovakia and Romania have only sporadically and not systematically used cluster initiatives.
When examining whether, in fact, firms located within regional clusters perform better and are more efficient than similar firms outside clusters, we do find positive results across countries and across sectors. The only country with negative impact from being located in a cluster is the Czech Republic.
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Cruz, Sara Cristina Santos. "Surveying Industrial Clusters: A comprehensive Bibliometric Account." Master's thesis, Faculdade de Economia da Universidade do Porto, 2007. http://hdl.handle.net/10216/7563.
Full textAbstract:
EconomiaMaster in Economics
Num mundo onde o paradigma da globalização se tornou uma realidade inquestionável, a dimensão `local tem ganho particular interesse como objecto de análise. Isto decorre do facto de os principais factores de competitividade global se encontrarem profundamente enraizados a um nível local. Neste contexto, os clusters, como entidades geográficas e sócio-relacionais, com um percurso evolutivo específico, uma identidade institucional e dinâmicas locais de conhecimento, tornaram-se elementos cruciais no desenvolvimento das regiões, assumindo um papel significativo nas políticas públicas. Apesar da sua importância crescente, o conceito de cluster tem sido alvo de uma aplicação discricionária, em termos do seu sentido e definição. Tendo em conta a evolução histórica deste conceito, tornou-se, então, necessário encontrar uma forma de organizar a literatura existente, numa tentativa de harmonizar esta multiplicidade de interpretações e significados. Esta dissertação tem por objectivo sistematizar o actual corpo de abordagens teóricas e estudos empíricos sobre clusters através de uma revisão aprofundada da literatura, complementada com um estudo bibliométrico, realizado com base em artigos publicados em jornais indexados nas bases de dados bibliográficas Econlit e EBSCO, no período de 1962 a 2007. Os principais resultados deste trabalho de investigação indicam que, para além da sua importância académica, o papel dos clusters tem também sido amplamente reconhecido no domínio político. Por outro lado, o interesse crescente na dimensão `local tem sido acompanhado por um emergente corpo de literatura sobre `globalização, redes globais e clusters . Além disso, por detrás do recente boom na literatura sobre clusters, está a importância de temas como as `abordagens sociais e baseadas nas `networks de contactos ou redes locais dos clusters, bem como as teorias baseadas no conhecimento. Estudos sobre sistemas regionais e nacionais de inovação e abordagens institucionais (relativas a culturas, governação e costumes locais das regiões) alcançaram particular importância a partir da década de 1990. Isto reflecte claramente as mais recentes tendências da literatura sobre clusters, que têm dado especial enfoque a factores sistémicos e institucionais . Finalmente, não obstante a correlação positiva entre a qualidade das publicações e a investigação formal e experimental, a evolução da literatura sobre clusters continua a ser maioritariamente apreciativa e descritiva.
As the global paradigm became an accepted reality, the local dimension has gained particular interest as an object of analysis. This is because key factors of global competitiveness have become deeply rooted at a local level. In this context, clusters, as geographical and socio-relational entities with a specific evolutionary path, institutional embeddedness and local knowledge dynamics, have become crucial elements in regional development, assuming a significant role in public policies. Despite its growing importance, the concept of cluster has been subject to a rather discretionary use in terms of interpretation and meaning. Since the multiplicity of definitions has flourished with the historical evolution of the cluster concept, it became necessary to find a way to organize the existing literature, in an attempt to overcome this multitude of notions and meanings. This dissertation aims to systematize the existing corpus of theoretical approaches and empirical studies on clusters by carrying out a thorough, qualitative survey of the cluster literature, complemented with a comprehensive bibliometric account, based on articles published in journals indexed in the Econlit and EBSCO bibliographic databases, from 1962 to 2007. The main outcomes of this research show that besides their importance in academic fields, the role of clusters has also been widely acknowledged in political spheres. Along with an increasing interest in the `local dimension, an emergent corpus of literature on global networks and clusters has also arisen. Moreover, behind the recent boom in the cluster literature is the influence of the prominent themes `local networks and social approaches and `knowledge-based theories . Studies on `regional and national innovation systems and `institutional approaches (mostly concerned with enrooted local cultures, governance and customs) have been achieving a particular importance since the 1990s. This clearly reflects the most recent trends in the cluster literature, which focus particularly on `systemic and `institutional factors. Finally, despite the positive correlation between the `quality of journals and related formal research, the evolution of the literature on clusters continues to be mostly appreciative-led.
7
Cruz, Sara Cristina Santos. "Surveying Industrial Clusters: A comprehensive Bibliometric Account." Dissertação, Faculdade de Economia da Universidade do Porto, 2007. http://hdl.handle.net/10216/7563.
Full textAbstract:
EconomiaMaster in Economics
Num mundo onde o paradigma da globalização se tornou uma realidade inquestionável, a dimensão `local tem ganho particular interesse como objecto de análise. Isto decorre do facto de os principais factores de competitividade global se encontrarem profundamente enraizados a um nível local. Neste contexto, os clusters, como entidades geográficas e sócio-relacionais, com um percurso evolutivo específico, uma identidade institucional e dinâmicas locais de conhecimento, tornaram-se elementos cruciais no desenvolvimento das regiões, assumindo um papel significativo nas políticas públicas. Apesar da sua importância crescente, o conceito de cluster tem sido alvo de uma aplicação discricionária, em termos do seu sentido e definição. Tendo em conta a evolução histórica deste conceito, tornou-se, então, necessário encontrar uma forma de organizar a literatura existente, numa tentativa de harmonizar esta multiplicidade de interpretações e significados. Esta dissertação tem por objectivo sistematizar o actual corpo de abordagens teóricas e estudos empíricos sobre clusters através de uma revisão aprofundada da literatura, complementada com um estudo bibliométrico, realizado com base em artigos publicados em jornais indexados nas bases de dados bibliográficas Econlit e EBSCO, no período de 1962 a 2007. Os principais resultados deste trabalho de investigação indicam que, para além da sua importância académica, o papel dos clusters tem também sido amplamente reconhecido no domínio político. Por outro lado, o interesse crescente na dimensão `local tem sido acompanhado por um emergente corpo de literatura sobre `globalização, redes globais e clusters . Além disso, por detrás do recente boom na literatura sobre clusters, está a importância de temas como as `abordagens sociais e baseadas nas `networks de contactos ou redes locais dos clusters, bem como as teorias baseadas no conhecimento. Estudos sobre sistemas regionais e nacionais de inovação e abordagens institucionais (relativas a culturas, governação e costumes locais das regiões) alcançaram particular importância a partir da década de 1990. Isto reflecte claramente as mais recentes tendências da literatura sobre clusters, que têm dado especial enfoque a factores sistémicos e institucionais . Finalmente, não obstante a correlação positiva entre a qualidade das publicações e a investigação formal e experimental, a evolução da literatura sobre clusters continua a ser maioritariamente apreciativa e descritiva.
As the global paradigm became an accepted reality, the local dimension has gained particular interest as an object of analysis. This is because key factors of global competitiveness have become deeply rooted at a local level. In this context, clusters, as geographical and socio-relational entities with a specific evolutionary path, institutional embeddedness and local knowledge dynamics, have become crucial elements in regional development, assuming a significant role in public policies. Despite its growing importance, the concept of cluster has been subject to a rather discretionary use in terms of interpretation and meaning. Since the multiplicity of definitions has flourished with the historical evolution of the cluster concept, it became necessary to find a way to organize the existing literature, in an attempt to overcome this multitude of notions and meanings. This dissertation aims to systematize the existing corpus of theoretical approaches and empirical studies on clusters by carrying out a thorough, qualitative survey of the cluster literature, complemented with a comprehensive bibliometric account, based on articles published in journals indexed in the Econlit and EBSCO bibliographic databases, from 1962 to 2007. The main outcomes of this research show that besides their importance in academic fields, the role of clusters has also been widely acknowledged in political spheres. Along with an increasing interest in the `local dimension, an emergent corpus of literature on global networks and clusters has also arisen. Moreover, behind the recent boom in the cluster literature is the influence of the prominent themes `local networks and social approaches and `knowledge-based theories . Studies on `regional and national innovation systems and `institutional approaches (mostly concerned with enrooted local cultures, governance and customs) have been achieving a particular importance since the 1990s. This clearly reflects the most recent trends in the cluster literature, which focus particularly on `systemic and `institutional factors. Finally, despite the positive correlation between the `quality of journals and related formal research, the evolution of the literature on clusters continues to be mostly appreciative-led.
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Hess, Cassiano Ricardo. "MDX-cc: ambiente de programação paralela aplicado a cluster de clusters." Pontifícia Universidade Católica do Rio Grande do Sul, 2003. http://hdl.handle.net/10923/1655.
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Previous issue date: 2003Due to the appearance of fast communication networks, such as Myrinet and SCI, it becames possible the construction of new architectures based on commodity, off-the-shelf machines (PCs and workstations) connected by this kind of network - which are been called clusters. Such architectures are becoming an alternative execution platform for complex parallel applications, mainly due to the cost/benefit relation they present. The diversity of fast networks leads to the interconnection of clusters, building an architecture called cluster of clusters. One of the main problems in the use of clusters of clusters is the programming software used for parallel application development, since this kind of architecture has some characteristics that must be addressed by the programming language or environment in order to provide high performance. This work describes the development of a message passing parallel programming environment for cluster of clusters, the MDX-cc. This environment was projected based on the MDX system [PRE98][HES01] and a first version has been implemented supporting communication over Fast-Ethernet, SCI and Myrinet networks. The main goal of MDX-cc is to provide communication and synchronization of processes that run on interconnected clusters. Thanks to its modular architecture and the use of specific communication protocols dedicated to each network interface, MDX-cc provides a simple programming interface, with a small set of primitives, and also provides a transparent communication among processes running on different network-based clusters.
Em razão do surgimento de redes de comunicação de alta velocidade, tais como Myrinet e SCI, a construção de arquiteturas baseadas em máquinas comuns (PCs e estações de trabalho) conectadas por esse tipo de rede - o que se denomina agregado (ou cluster) - tornou-se viável. Tais arquiteturas vêm se consolidando como plataformas alternativas para a execução de aplicações paralelas complexas, principalmente devido à relação custo/benefício que oferecem. Esse avanço das tecnologias de redes possibilita também a agregação de clusters, formando uma estrutura de cluster de clusters, como uma única máquina paralela. Um dos principais problemas no uso de cluster de clusters é o software utilizado para o desenvolvimento de aplicações paralelas, visto que cada agregado envolvido na estrutura possui certas características que precisam ser tratadas pela linguagem ou ambiente de programação, visando o alcance de alto desempenho. Esta dissertação tem como objetivo apresentar uma ferramenta de programação paralela por troca de mensagens que executa sobre uma estrutura de cluster de clusters: o MDX-cc. A ferramenta foi concebida tendo como base o sistema MDX [PRE98][HES01] e uma primeira versão foi implementada oferecendo suporte à comunicação em agregados com redes SCI, Myrinet e Fast-Ethernet. O principal objetivo do MDX-cc é oferecer recursos de comunicação e sincronização de processos que rodam em agregados interligados. Por sua arquitetura modular e abstração do uso de protocolos de comunicação dedicados a cada tecnologia de rede, o MDX-cc oferece uma interface de programação simples, com um conjunto reduzido de primitivas, e provê transparência total na comunicação entre processos que executam em nós de clusters com tecnologias de rede distintas.
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Ballestrin, Silvia <1989>. "Industrial Clusters in BRIC countries. An analysis of the economic geography of industrial clusters in BRIC countries and the cluster development policies." Master's Degree Thesis, Università Ca' Foscari Venezia, 2013. http://hdl.handle.net/10579/3656.
Full textAbstract:
La tesi si propone di analizzare la geografia economica dei cluster industriali nei BRIC. Essa è costituita da una prima parte in cui vengono riassunte le principali teorie economiche sviluppatesi attorno al concetto di cluster e si definiscono i principali tratti economici, demografici e sociali dei paesi presi in considerazione, i BRIC (Brasile, Russia, India, Cina). La seconda parte è invece dedicata all'analisi della geografia economica dei cluster industriali nei suddetti paesi, utilizzando una comune chiave di lettura. Lo scopo principale è quello di analizzare come questo modello di organizzazione industriale possa farsi promotore di sviluppo, agendo sul grado di competitività sostenibile delle economie emergenti in oggetto.
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Bowlan, John. "Electric dipole moments, cluster metallicity, and the magnetism of rare earth clusters." Diss., Georgia Institute of Technology, 2010. http://hdl.handle.net/1853/34751.
Full textAbstract:
One of the fundamental properties of bulk metals is the cancellation of electric
fields. The free charges inside of a metal will move until they find an arrangement where
the internal electric field is zero. This implies that the electric dipole moment of a metal
particle should be exactly zero, because an electric dipole moment requires a net separation
of charge and thus a nonzero internal electric field.
This thesis is an experimental study to see if this property continues to hold for tiny sub-
nanometer metal particles called clusters (2 - 200 atom, R < 1 nm). We have measured the
electric dipole moments of metal clusters made from 15 pure elements using a molecular
beam electric deflection technique. We find that the observed dipole moments vary a great
deal across the periodic table. Alkali metals have zero dipole moments, while transition
metals and lanthanides all have dipole moments which are highly size dependent. In most
cases, the measured dipole moments are independent of temperature (T = 20 - 50 K), and
when there is a strong temperature dependence this suggests that there is a new state of
matter present. Our interpretation of these results are that those clusters which have a non-
zero dipole moment are non-metallic, in the sense that their electrons must be localized
and prevented from moving to screen the internal field associated with a permanent dipole
moment.
This interpretation gives insight to several related phenomena and applications. We
briefly discuss an example cluster system RhN where the measured electric dipole moments
appear to be correlated with a the N2O reactivity.
Finally, we discuss a series of magnetic deflection experiments on lanthanide clusters
(Pr, Ho, Tb, and Tm). The magnetic response of these clusters is very complex and highly
sensitive to size and temperature. We find that PrN (which is non-magnetic in the bulk) becomes magnetic in clusters and TmN clusters have magnetic moments lower than the atomic value as well as the bulk saturation value implying that the magnetic order in the cluster involves non-collinear or antiferromagnetic order. HoN and TbN show very similar size dependent trends suggesting that these clusters have similar structures.
Books on the topic "Clusters"
1
Nguyen, Minh Tho, and Boggavarapu Kiran, eds. Clusters. Cham: Springer International Publishing, 2017. http://dx.doi.org/10.1007/978-3-319-48918-6.
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1930-, Cotton F. Albert, ed. Clusters. Berlin: Springer-Verlag, 1985.
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1930-, Cotton F. Albert, ed. Clusters. Berlin: Springer-Verlag, 1985.
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Feretti, L., I. M. Gioia, and G. Giovannini. Merging processes in galaxy clusters. Dordrecht: Springer, 2011.
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Munn-Venn, Trefor. Clusters of opportunity, clusters of risk. Ottawa: Conference Board of Canada, 2004.
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Archinal, Brent A. Star clusters. Richmond, VA: Willmann-Bell, 2003.
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Kiss, Katalin É., and Henk van Riemsdijk, eds. Verb Clusters. Amsterdam: John Benjamins Publishing Company, 2004. http://dx.doi.org/10.1075/la.69.
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Sedita, Silvia Rita, and Silvia Blasi, eds. Rethinking Clusters. Cham: Springer International Publishing, 2021. http://dx.doi.org/10.1007/978-3-030-61923-7.
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Wilson, John F., Chris Corker, and Joe Lane. Industrial Clusters. New York: Routledge, 2022. http://dx.doi.org/10.4324/9781003036357.
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Cardona III, Charles A. Star Clusters. New York, NY: Springer New York, 2010. http://dx.doi.org/10.1007/978-1-4419-7040-4.
Full textBook chapters on the topic "Clusters"
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Malthe-Sørenssen, Anders. "Geometry of Clusters." In Percolation Theory Using Python, 63–84. Cham: Springer International Publishing, 2024. http://dx.doi.org/10.1007/978-3-031-59900-2_5.
Full textAbstract:
AbstractWe have seen how we can characterize clusters by their mass, s. As p approaches $$p:c$$ p c , the typical cluster size s increases as well as the characteristic cluster diameter. In this chapter we will discuss the geometry of clusters, and by geometry we will mean how the number of sites in a cluster is related to the linear size of the cluster. We will introduce several measures to characterize the spatial extent, the characteristic radius $$R:s$$ R s , of clusters of size s. We will measure $$R:s$$ R s to motivate that it is proportional to $$s^1/D$$ s 1 ∕ D , where D is a new exponent characterizing the dimension of clusters. We will demonstrate that the percolation system is characterized by two lengths, the system size L and a characteristic cluster size $$\xi $$ ξ , and that the system shows fractal, self-similar scaling when the characteristic length diverges. We develop scaling theories for $$P(s,L)$$ P ( s , L ) for $$p>p_c$$ p > p c and lay the foundations for a geometrical understanding and description of the spanning cluster.
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Jena, P., S. N. Khanna, and B. K. Rao. "Clusters and Cluster Reactions." In Density Functional Theory of Molecules, Clusters, and Solids, 123–51. Dordrecht: Springer Netherlands, 1996. http://dx.doi.org/10.1007/978-94-011-0487-6_5.
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Barrientos, Armando. "Clusters." In Social Protection in Latin America, 245–70. Cham: Springer International Publishing, 2024. http://dx.doi.org/10.1007/978-3-031-49795-7_8.
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AbstractThe chapter studies differences and similarities in social protection institutions across countries in the region with the aim of identifying country groupings or clusters. The methodological approach implemented was borrowed from the literature in social policy regimes. The grouping of countries is based on the causal outcomes of social protection institutions—employment, protection, and incorporation—and repeated for the periods associated with institutional development. The results largely confirm the findings in the social policy regime literature. There are three main clusters of countries: Southern cone countries plus Costa Rica, Mexico, and Panama; Andean countries including Paraguay; and Central American countries. Repeating the cluster analysis for different periods characterised by social protection reforms provides additional insights. The temporal analysis suggests a measure of continuity in the country groupings over time, but it also shows disruption in the membership of the clusters during the neoliberal period. Cluster memberships loosen up during this period, especially for countries like Chile and Mexico. Paying attention to measures of the distribution of transfers introduces fluidity in the membership sets of Andean and Central American countries.
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Preissl, Brigitte, and Laura Solimene. "Clusters." In The Dynamics of Clusters and Innovation, 41–72. Heidelberg: Physica-Verlag HD, 2003. http://dx.doi.org/10.1007/978-3-642-50011-4_3.
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Turner, J. Rick. "Clusters." In Encyclopedia of Behavioral Medicine, 431–32. New York, NY: Springer New York, 2013. http://dx.doi.org/10.1007/978-1-4419-1005-9_998.
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Nahler, Gerhard. "clusters." In Dictionary of Pharmaceutical Medicine, 30. Vienna: Springer Vienna, 2009. http://dx.doi.org/10.1007/978-3-211-89836-9_229.
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Morss, Lester R. "Clusters." In Inorganic Reactions and Methods, 16. Hoboken, NJ, USA: John Wiley & Sons, Inc., 2007. http://dx.doi.org/10.1002/9780470145296.ch15.
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Mandich, Mary. "Clusters." In Springer Handbook of Atomic, Molecular, and Optical Physics, 589–606. New York, NY: Springer New York, 2006. http://dx.doi.org/10.1007/978-0-387-26308-3_39.
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Stace, A. J., H. Haberland, H. Kornmeier, H. Langosch, M. Oschwald, and G. Tanner. "Clusters." In 100 Years of Physical Chemistry, 23–34. Cambridge: Royal Society of Chemistry, 2007. http://dx.doi.org/10.1039/9781847550002-00023.
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Karlsson, Charlie. "Clusters." In The New Palgrave Dictionary of Economics, 1690–708. London: Palgrave Macmillan UK, 2018. http://dx.doi.org/10.1057/978-1-349-95189-5_3038.
Full textConference papers on the topic "Clusters"
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Kennedy, Richard, Chung-Yi Kung, Stephen C. Foster, and Terry A. Miller. "Ionic clusters." In International Laser Science Conference. Washington, D.C.: Optica Publishing Group, 1986. http://dx.doi.org/10.1364/ils.1986.jfc3.
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Details of recent experiments involving charged clusters are described. In one experiment these clusters are prepared in a supersonic expansion and their laser-induced fluorescence spectra recorded. The clusters consist of a charged chromophore and neutral species bound to it. Results obtained include spectral shifts, cluster vibrational progressions, and resulting potential surfaces.
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Kennedy, Richard, Chung-Yi Kung, Stephen Foster, and Terry A. Miller. "Ionic clusters." In OSA Annual Meeting. Washington, D.C.: Optica Publishing Group, 1986. http://dx.doi.org/10.1364/oam.1986.fc3.
Full textAbstract:
Details of recent experiments involving charged clusters are described. In one experiment these clusters are prepared in a supersonic expansion and their laser-induced fluorescence spectra recorded. The clusters consist of a charged Chromophore and neutral species bound to it. Results obtained include spectral shifts, cluster vibrational progressions, and resulting potential surfaces.
3
Zimmerer, Georg. "Time-Resolved Spectroscopy as a Probe to the Electronic Structure and the Dynamics of Clusters." In Free-Electron Laser Applications in the Ultraviolet. Washington, D.C.: Optica Publishing Group, 1988. http://dx.doi.org/10.1364/fel.1988.sb1.
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The remarkable progress in the area of supersonic beam techniques1 provides the basis for the exciting field of the physics of clusters which bridge the gap between molecules and condensed matter. For many years, the characterization of cluster beams (size distribution as a function of the relevant expansion parameters etc.), the geometrical structure and the stability of clusters were investigated. Among others, "magic numbers" in clusters size distributions were found2 as well as structural units which are not compatible with translational symmetry of a solid3. More recently, the photoionization of clusters4 including photoion-photoelectron coincidence experiments5 was successfully attacked.
4
Martin, M. Z., S. R. Desai, C. S. Feigerle, and J. C. Miller. "Laser-Induced Chemistry within Clusters." In Laser Applications to Chemical and Environmental Analysis. Washington, D.C.: Optica Publishing Group, 1996. http://dx.doi.org/10.1364/lacea.1996.lfa.6.
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Clusters comprise an interesting environment for the study of chemical reactions. Binary cluster complexes can be produced which combine a variety of potential reactant partners in various proportions in an intimate, yet controlled arrangement. Molecules or ions within such a cluster (i.e. solvated) have properties which are intermediate between those of isolated species and of species in solution or in bulk. Furthermore as the cluster size increases their properties may smoothly change until the condensed-phase regime is reached. But, since clusters are generated and interrogated in the gas phase, powerful techniques such as mass spectrometry may be used for characterization. Such clusters may then represent model environments which simulate real world situations such as aerosols or cells. Similarly, the chemistry of such clusters may also differ in significant ways from that of the isolated species.
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Vormoor, O. "Reorganization of clusters in cluster-cluster-aggregation." In Sixth international conference on x-ray microscopy (XRM99). AIP, 2000. http://dx.doi.org/10.1063/1.1291152.
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Engelking, Paul C. "Photoinduced evaporation of charged clusters." In OSA Annual Meeting. Washington, D.C.: Optica Publishing Group, 1986. http://dx.doi.org/10.1364/oam.1986.wg29.
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The clusters remaining after photoinduced evaporation of an initial cluster are predicted by a statistical model and compared with recent experiments on ( CO 2 ) n + clusters. The model includes a modification to an RRK/QET formalism, to satisfy detailed balance for ion molecule reactions. This gives a correct average kinetic energy release approximately twice that of uncorrected RRK/QET. Product cluster distributions observed in photodissociation experiments are predicted by a statistical Monte Carlo calculation.
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Gontcharov, G., A. Mosenkov, M. Khovritchev, V. Il’in, A. Marchuk, S. Savchenko, A. Smirnov, and P. Usachev. "The properties of Galactic globular clusters from Gaia EDR3 and other data compared with theoretical isochrones." In ASTRONOMY AT THE EPOCH OF MULTIMESSENGER STUDIES. Proceedings of the VAK-2021 conference, Aug 23–28, 2021. Crossref, 2022. http://dx.doi.org/10.51194/vak2021.2022.1.1.182.
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We fit theoretical isochrones from different models of internal structure and evolution of stars to photometric data for thestars in globular clusters of our Galaxy. To select cluster members, determine cluster sizes and calculate systemic propermotions, we use parallaxes and proper motions from Gaia EDR3. To calculate the most probable distance, age, interstellarextinction in a variety of filters and differential reddening in cluster fields, we use photometry in more than 26 filters betweenthe ultraviolet and mid-infrared waverange from HST, Gaia EDR3, Pan-STARRS DR1, DES, SDSS, unWISE, SAGE andother datasets in combination with the PARSEC, MIST, DSEP, and BaSTI-IAC isochrones, as for the solar metallicityscale as for alpha- and helium-enriched scales. The metallicity and enrichment of the clusters is taken from spectroscopicobservations and tested for compliance with the photometric results. We carry out a thorough analysis of random andsystematic uncertainties of the obtained results. The derived extinctions in many filters allow us to estimate an empiricalextinction law for each cluster. A complete analysis has been performed for five clusters (NGC288, NGC362, NGC5904,NGC6205, and NGC6218), a preliminary analysis, based on the Gaia EDR3 astrometry and photometry only, has beendone for 38 more clusters. The main conclusions are as follows. First, unprecedentedly accurate astrometry of Gaia EDR3allows us to segregate the cluster members from fore- and background stars and to indicate that the size of many clustersis much larger than previously thought. Second, the distances, derived by us from the photometry-to-isochrone fitting, arestill more precise than distances from the Gaia EDR3 parallaxes. Third, contrary to the popular 2D reddening maps ofSchlegel-1998 and Planck, we found no clusters at high Galactic latitudes with an extinction A V < 0.1. Fourth, for thehorizontal branch second parameter quartet NGC 288–NGC 362–NGC 5904–NGC 6218, the age is undoubtedly the secondparameter.
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Syage, Jack A. "Time-resolved studies of chemical reactions in clusters." In OSA Annual Meeting. Washington, D.C.: Optica Publishing Group, 1991. http://dx.doi.org/10.1364/oam.1991.thdd3.
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Excited-state proton transfer (ESPT) rates in molecular clusters were measured as a function of cluster size using picosecond spectroscopy in a molecular beam mass spectrometer. ESPT from the S1 state of phenol to basic solvent clusters (NH3)n occurs for a critical solvent cluster size n ≥5 with a rate constant of k= (60 ± 10 ps)-1 for n = 5−7. ESPT showing critical cluster-size dependencies was also observed in the basic solvent N(CH3)3 (n ≃ 3). Proton transfer was not observed in the less basic solvent clusters (CH3OH) n and (H2O) n . Mixed solvent studies indicate that the addition of a dissimilar molecule to an otherwise neat solvent cluster impedes ESPT presumably due to a disruption of the hydrogen bonding network.
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Ditmire, T., J. W. G. Tisch, E. Springate, M. B. Mason, N. Hay, R. A. Smith, J. P. Marangos, and M. H. R. Hutchinson. "High Energy Explosion of Super-Heated Atomic Clusters." In Applications of High Field and Short Wavelength Sources. Washington, D.C.: Optica Publishing Group, 1997. http://dx.doi.org/10.1364/hfsw.1997.thb2.
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Though the nature of intense, short pulse laser interactions with single atoms and solid targets has been the subject of extensive experimental and theoretical investigation over the last 15 years, only recently has the nature of intense laser interactions with van der Waals bonded atomic clusters of 20 -100 Å been addressed in experiments. These experiments have suggested that the laser-cluster interaction is much more energetic than that of isolated atoms, producing bright x-ray emission (100 - 5000 eV photons) when a low density gas containing clusters is illuminated [1,2]. While experiments have indicated indirect evidence for keV electron production in the cluster through time resolved x-ray spectroscopic data [2], until recently no direct data on the exact nature of the kinetic energies produced by the intense irradiation of clusters existed. In this paper we present the first energy distribution measurements of both electrons and ions resulting from the interaction of a femtosecond laser pulse with van der Waals bonded clusters. We find that the cluster is rapidly heated by collisional inverse bremsstrahlung. This heats a sizable fraction of the electrons in the cluster to a temperature above 1 keV. The super-heated cluster then explodes, ejecting ions with substantial kinetic energy. In fact, ions with energy up to 1 MeV are produced in Xe clusters.
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Sekachev, Mikhail, Cheng-Xian Lin, Zhiyu Hu, and Don Dareing. "A Computational Study of Catalytic Platinum Nanoparticles With and Without OH Chemisorption During Reactions." In ASME 2008 3rd Energy Nanotechnology International Conference collocated with the Heat Transfer, Fluids Engineering, and Energy Sustainability Conferences. ASMEDC, 2008. http://dx.doi.org/10.1115/enic2008-53029.
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In this paper, various energies and geometries of pure platinum nanoparticles and those of platinum nanoparticles with adsorbed OH were investigated. Ten different platinum clusters of up to 28 atoms were studied using spin-unrestricted density functional theory (DFT) with a double numerical plus polarization basis set. Three different shapes were presented, and the effect of cluster size on binding energy, total energy, and HOMO-LUMO energy gap was investigated. The same set of calculations was performed for selected clusters with OH adsorbate on the Pt(111) surface. The results show that the stability of both the pure clusters and the clusters with adsorbed OH molecule increases with an increase of cluster size. This fact indicates that direct influence of the size of Pt cluster on the reaction rate is possible, and the understanding of how cluster size would affect binding energy is important. The effect of cluster size on total energy of molecule was shown to be a linear function independent of cluster type, as expected. We also found that optimized (stable) Pt clusters were bigger in size than that of the initial clusters, or clusters with bulk geometry.
Reports on the topic "Clusters"
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Ramis, Luis. Políticas de clusters: Análisis de clusters en Mendoza: Objetivos, mapping y selección de clusters, recomendaciones. Inter-American Development Bank, June 2005. http://dx.doi.org/10.18235/0007265.
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Presentación sobre el análisis de los clusters en Mendoza. Da a conocer los objetivos y alcance del proyecto, mapping de clusters y selección del piloto, la metodología de mejora de la competitividad en un cluster y por último, las recomendaciones para una política de competitividad basada en clusters.
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Kryzhanivs'kyi, Evstakhii, Liliana Horal, Iryna Perevozova, Vira Shyiko, Nataliia Mykytiuk, and Maria Berlous. Fuzzy cluster analysis of indicators for assessing the potential of recreational forest use. [б. в.], October 2020. http://dx.doi.org/10.31812/123456789/4470.
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Cluster analysis of the efficiency of the recreational forest use of the region by separate components of the recreational forest use potential is provided in the article. The main stages of the cluster analysis of the recreational forest use level based on the predetermined components were determined. Among the agglomerative methods of cluster analysis, intended for grouping and combining the objects of study, it is common to distinguish the three most common types: the hierarchical method or the method of tree clustering; the K-means Clustering Method and the two-step aggregation method. For the correct selection of clusters, a comparative analysis of several methods was performed: arithmetic mean ranks, hierarchical methods followed by dendrogram construction, K- means method, which refers to reference methods, in which the number of groups is specified by the user. The cluster analysis of forestries by twenty analytical grounds was not proved by analysis of variance, so the re-clustering of certain objects was carried out according to the nine most significant analytical features. As a result, the forestry was clustered into four clusters. The conducted cluster analysis with the use of different methods allows us to state that their combination helps to select reasonable groupings, clearly illustrate the clustering procedure and rank the obtained forestry clusters.
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Lueninghoener, Cory. Clusters @ LANL. Office of Scientific and Technical Information (OSTI), June 2020. http://dx.doi.org/10.2172/1632663.
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Kerr, William, and Frédéric Robert-Nicoud. Tech Clusters. Cambridge, MA: National Bureau of Economic Research, June 2020. http://dx.doi.org/10.3386/w27421.
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Owen, R. K. Quantum Monte Carlo methods and lithium cluster properties. [Atomic clusters]. Office of Scientific and Technical Information (OSTI), December 1990. http://dx.doi.org/10.2172/7204421.
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Rodríguez-Clare, Andrés. Coordination Failures, Clusters and Microeconomic Interventions. Inter-American Development Bank, December 2005. http://dx.doi.org/10.18235/0010959.
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This paper discusses coordination failures, their relevance to developing countries, and the circumstances under which they occur, arguing that that clusters can be seen as agglomerations of firms and organizations in related economic activities among which coordination failures are likely to arise. In other words, clusters provide opportunities for microeconomic interventions that promote coordination and collective action to improve productivity. Subsequently presented is a model of a small economy plagued by sector or cluster-specific coordination failures, which demonstrates that policy should foster cooperation in sectors where the economy already shows comparative advantage. In regard to innovation, general policies that aim to increase innovation across the board are likely to be inferior to policies that take a more selective approach by trying to induce the development of innovation clusters in areas of comparative advantage. The paper concludes with suggestions on how an understanding of coordination failures and clusters can form the basis for a set of effective microeconomic interventions for middle-income countries.
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Campi, Mercedes, and Marco Dueñas. Clusters and Resilience during the COVID–19 Crisis: Evidence from Colombian Exporting Firms. Inter-American Development Bank, October 2022. http://dx.doi.org/10.18235/0004474.
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In this paper, we characterize the geography of Colombian exporting clusters and analyze how the COVID-19 crisis has affected Colombian exporters. We contribute to the industrial clusters literature by defining exporting clusters with bipartite network analysis and community detection tools. The methodology allows us to empirically detect product clusters, which are compared with an alternative definition of industrial clusters, and to consider the centrality of firms within clusters. Then, we analyze the firms trade margins during the COVID-19 crisis to evaluate whether belonging to an exporting cluster can be a source of resilience for firms. We find that clusters do not automatically lead to higher resilience and that there are differences in how firms react to a crisis within clusters. Identifying the relevant firms characteristics can guide policymakers to activate the mechanisms that generate resilience.
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Glaeser, Edward, William Kerr, and Giacomo A. M. Ponzetto. Clusters of Entrepreneurship. Cambridge, MA: National Bureau of Economic Research, September 2009. http://dx.doi.org/10.3386/w15377.
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Bonita, Manuel, Fernando Correa, Harri Ahveninen, and Pertti Veijalainen. Forest Clusters: A Competitive Model for Latin America. Inter-American Development Bank, March 2002. http://dx.doi.org/10.18235/0008811.
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contribute to success in the forest business. These include sound macroeconomic and long-term forest policies, secure land tenure, support from related education and technology programs, and cooperation among the various industries involved in producing and marketing forest products and services. The basic objective of this document is to examine the potential for creating forest clusters in Latin America. These clusters are based on the experience of Nordic countries and on studies of six natural resource-based clusters, identified by ECLAC/CEPAL. Specifically, this study aims to: 1) Identify issues and opportunities for forestry and the forest industry as a vehicle for development in Latin America; 2) Define lessons for forest cluster development in Latin America in the light of good-practice experiences in the Nordic countries; 3) Formulate policy recommendations for the selected Latin American countries on how to develop and environmentally manage different types of forest clusters.
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Monteiro, Joana, Beatriz Kury, and Angela Da Rocha. The Role of Flagship Firms, External Actors and Support Institutions in the Emergence of Successful Export Activities in Brazil: Two Industrial Cluster Studies. Inter-American Development Bank, September 2009. http://dx.doi.org/10.18235/0011331.
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This paper examines the process by which firms in a cluster start to export based on systemic interactions and the process of diffusion of exporting as a business strategy within the cluster. Two Brazilian manufacturing industries are studied, and within each one a geographic cluster was identified as the origin of dynamic export growth. Players in each industrial cluster, as well as other significant players, were interviewed or identified using secondary sources, and extensive secondary data research was undertaken to study clusters' historical development. Detailed analysis and a comparison of the two experiences made it possible to draw some general conclusions concerning the similarities and differences between the two clusters in terms of the adoption and diffusion of exporting.