3,928 research outputs found
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A review of research on the growth of multinational enterprises: a Penrosean lens
We provide a comprehensive review of the growth of multinational enterprises (MNEs) based on a quarter-century (25 years) of scholarly international business publications. We synthesize research insights on the determinants of the growth of MNEs through the lens of Penrose’s theory of firm growth, which is the most influential theoretical perspective on firm growth. The review takes stock of the research findings on the facilitators, constraints, and the trajectory of growth of MNEs, and elaborates on the commonalities and differences between research on the growth of MNEs that draws on Penrose’s theory and research that does not. This comparison highlights the opportunity to build an internally coherent theory of the growth of MNEs, that is, a theory that connects ‘what an MNE is’ to ‘what determines an MNE’s growth.’ It also indicates that past research placed a strong emphasis on exogenous factors (e.g., cross-country distances) as key constraints on growth even though the Penrosean lens suggests a close consideration of endogenous factors that drive international growth, as well as endogenizing the ostensibly exogenous growth determinants. The review highlights the importance of firm-specific managerial knowledge and learning, which shapes the direction of the growth of MNEs and ensures its administrative coherence
Heterogeneous domain adaptation for multiple classes
In this paper, we present an efficient multi-class heterogeneous domain adaptation method, where data from source and target domains are represented by heterogeneous features of different dimensions. Specifically, we propose to reconstruct a sparse feature transformation matrix to map the weight vector of classifiers learned from the source domain to the target domain. We cast this learning task as a compressed sensing problem, where each binary classifier induced from multiple classes can be deemed as a measurement sensor. Based on the compressive sensing theory, the estimation error of the transformation matrix decreases with the increasing number of classifiers. Therefore, to guarantee reconstruction performance, we construct sufficiently many binary classifiers based on the error correcting output coding. Extensive experiments are conducted on both a toy dataset and three real-world datasets to verify the superiority of our proposed method over existing state-of-the-art HDA methods in terms of prediction accuracy
Multi-class Heterogeneous Domain Adaptation
© 2019 Joey Tianyi Zhou, Ivor W. Tsang, Sinno Jialin Pan, Mingkui Tan. A crucial issue in heterogeneous domain adaptation (HDA) is the ability to learn a feature mapping between different types of features across domains. Inspired by language translation, a word translated from one language corresponds to only a few words in another language, we present an efficient method named Sparse Heterogeneous Feature Representation (SHFR) in this paper for multi-class HDA to learn a sparse feature transformation between domains with multiple classes. Specifically, we formulate the problem of learning the feature transformation as a compressed sensing problem by building multiple binary classifiers in the target domain as various measurement sensors, which are decomposed from the target multi-class classification problem. We show that the estimation error of the learned transformation decreases with the increasing number of binary classifiers. In other words, for adaptation across heterogeneous domains to be successful, it is necessary to construct a sufficient number of incoherent binary classifiers from the original multi-class classification problem. To achieve this, we propose to apply the error correcting output correcting (ECOC) scheme to generate incoherent classifiers. To speed up the learning of the feature transformation across domains, we apply an efficient batch-mode algorithm to solve the resultant nonnegative sparse recovery problem. Theoretically, we present a generalization error bound of our proposed HDA method under a multi-class setting. Lastly, we conduct extensive experiments on both synthetic and real-world datasets to demonstrate the superiority of our proposed method over existing state-of-the-art HDA methods in terms of prediction accuracy and training efficiency
Discovery of an inhibitor of the production of the Pseudomonas aeruginosa virulence factor pyocyanin in wild-type cells.
Pyocyanin is a small molecule produced by Pseudomonas aeruginosa that plays a crucial role in the pathogenesis of infections by this notorious opportunistic pathogen. The inhibition of pyocyanin production has been identified as an attractive antivirulence strategy for the treatment of P. aeruginosa infections. Herein, we report the discovery of an inhibitor of pyocyanin production in cultures of wild-type P. aeruginosa which is based around a 4-alkylquinolin-2(1H)-one scaffold. To the best of our knowledge, this is the first reported example of pyocyanin inhibition by a compound based around this molecular framework. The compound may therefore be representative of a new structural sub-class of pyocyanin inhibitors, which could potentially be exploited in in a therapeutic context for the development of critically needed new antipseudomonal agents. In this context, the use of wild-type cells in this study is notable, since the data obtained are of direct relevance to native situations. The compound could also be of value in better elucidating the role of pyocyanin in P. aeruginosa infections. Evidence suggests that the active compound reduces the level of pyocyanin production by inhibiting the cell-cell signalling mechanism known as quorum sensing. This could have interesting implications; quorum sensing regulates a range of additional elements associated with the pathogenicity of P. aeruginosa and there is a wide range of other potential applications where the inhibition of quorum sensing is desirable.The research leading to these results has received funding from the European Research Council under the European Union’s Seventh Framework Programme (FP7/2007-2013)/ERC grant agreement no [279337/DOS]. In addition, the group research was supported by grants from the Engineering and Physical Sciences Research Council, Biotechnology and Biological Sciences Research Council, Medical Research Council and Welcome Trust. Y.S.T. was supported by an A*STAR Graduate Scholarship
Observation of pseudogap behavior in a strongly interacting Fermi gas
Ultracold atomic Fermi gases present an opportunity to study strongly
interacting Fermi systems in a controlled and uncomplicated setting. The
ability to tune attractive interactions has led to the discovery of
superfluidity in these systems with an extremely high transition temperature,
near T/T_F = 0.2. This superfluidity is the electrically neutral analog of
superconductivity; however, superfluidity in atomic Fermi gases occurs in the
limit of strong interactions and defies a conventional BCS description. For
these strong interactions, it is predicted that the onset of pairing and
superfluidity can occur at different temperatures. This gives rise to a
pseudogap region where, for a range of temperatures, the system retains some of
the characteristics of the superfluid phase, such as a BCS-like dispersion and
a partially gapped density of states, but does not exhibit superfluidity. By
making two independent measurements: the direct observation of pair
condensation in momentum space and a measurement of the single-particle
spectral function using an analog to photoemission spectroscopy, we directly
probe the pseudogap phase. Our measurements reveal a BCS-like dispersion with
back-bending near the Fermi wave vector k_F that persists well above the
transition temperature for pair condensation
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Penrose's The Theory of the Growth of the Firm: an exemplar of engaged scholarship
Edith Penrose's (1959) classic book, The Theory of the Growth of the Firm, made a substantial impact on strategic management research, especially in the context of the resource-based view of the firm, and the ripple effects of her impact continue to unfold today in various disciplines. The book serves as a remarkably rich source of inspiration for scholarly research and a generative source of ideas, which are waiting to be further developed. In this paper, we examine Penrose's (1959) classic and provide: (1) the process by which this book came about; (2) a summary of its key ideas; (3) the subsequent impact of the book, in which we focus on mathematical models; and (4) a discussion of some of the research lessons learned from this exemplar of engaged scholarship. We invite management science and operations scholars to discover the rich scientific world of Edith Penrose and experience the product and process of her research creativit
Penrose's The Theory of the Growth of the Firm: an exemplar of engaged scholarship
Edith Penrose's (1959) classic book, The Theory of the Growth of the Firm, made a substantial impact on strategic management research, especially in the context of the resource-based view of the firm, and the ripple effects of her impact continue to unfold today in various disciplines. The book serves as a remarkably rich source of inspiration for scholarly research and a generative source of ideas, which are waiting to be further developed. In this paper, we examine Penrose's (1959) classic and provide: (1) the process by which this book came about; (2) a summary of its key ideas; (3) the subsequent impact of the book, in which we focus on mathematical models; and (4) a discussion of some of the research lessons learned from this exemplar of engaged scholarship. We invite management science and operations scholars to discover the rich scientific world of Edith Penrose and experience the product and process of her research creativit
A novel COMP mutation in a pseudoachondroplasia family of Chinese origin
<p>Abstract</p> <p>Background</p> <p>Pseudoachondroplasia (PSACH) is caused exclusively by mutations in the gene for cartilage oligomeric matrix protein (<it>COMP</it>). Only a small number of studies have documented the clinical phenotype and genetic basis in Chinese PSACH patients.</p> <p>Case presentation</p> <p>We investigated a four-generation PSACH pedigree of Chinese Han origin. Two patients and two unaffected individuals were recruited for clinical evaluation and molecular genetic analysis. The genomic DNA was extracted from peripheral blood leukocytes. Polymerase chain reaction (PCR) was adopted to amplify the 8-19 exons of <it>COMP </it>gene. Then the products were sequenced bi-directionally for screening mutation. Clinical evaluation revealed that PSACH patients in this pedigree had a severe disproportionate short stature (-10SD). A heterozygous TGTCCCTGG insertion in exon 13, between nucleotide 1352T and 1353G, were identified in the patients except the unaffected individuals, which resulted in a three-amino-acid insertion (451V_452P ins VPG) in the sixth calmodulin-like repeat of the <it>COMP </it>protein.</p> <p>Conclusion</p> <p>This c. 1352_1353ins TGTCCCTGG is a novel mutation responsible for severe familial PSACH.</p
Impact of FTO genotypes on BMI and weight in polycystic ovary syndrome : a systematic review and meta-analysis
Aims/hypothesis
FTO gene single nucleotide polymorphisms (SNPs) have been shown to be associated with obesity-related traits and type 2 diabetes. Several small studies have suggested a greater than expected effect of the FTO rs9939609 SNP on weight in polycystic ovary syndrome (PCOS). We therefore aimed to examine the impact of FTO genotype on BMI and weight in PCOS.
Methods
A systematic search of medical databases (PubMed, EMBASE and Cochrane CENTRAL) was conducted up to the end of April 2011. Seven studies describing eight distinct PCOS cohorts were retrieved; seven were genotyped for SNP rs9939609 and one for SNP rs1421085. The per allele effect on BMI and body weight increase was calculated and subjected to meta-analysis.
Results
A total of 2,548 women with PCOS were included in the study; 762 were TT homozygotes, 1,253 had an AT/CT genotype, and 533 were AA/CC homozygotes. Each additional copy of the effect allele (A/C) increased the BMI by a mean of 0.19 z score units (95% CI 0.13, 0.24; p = 2.26 × 10−11) and body weight by a mean of 0.20 z score units (95% CI 0.14, 0.26; p = 1.02 × 10−10). This translated into an approximately 3.3 kg/m2 increase in BMI and an approximately 9.6 kg gain in body weight between TT and AA/CC homozygotes. The association between FTO genotypes and BMI was stronger in the cohorts with PCOS than in the general female populations from large genome-wide association studies. Deviation from an additive genetic model was observed in heavier populations.
Conclusions/interpretation
The effect of FTO SNPs on obesity-related traits in PCOS seems to be more than two times greater than the effect found in large population-based studies. This suggests an interaction between FTO and the metabolic context or polygenic background of PCOS
Identification, replication and characterization of epigenetic remodelling in the aging genome:A cross population analysis
Aging is a complex biological process regulated by multiple cellular pathways and molecular mechanisms including epigenetics. Using genome-wide DNA methylation data measured in a large collection of Scottish old individuals, we performed discovery association analysis to identify age-methylated CpGs and replicated them in two independent Danish cohorts. The double-replicated CpGs were characterized by distribution over gene regions and location in relation to CpG islands. The replicated CpGs were further characterized by involvement in biological pathways to study their functional implications in aging. We identified 67,604 age-associated CpG sites reaching genome-wide significance of FWE
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