1,848 research outputs found
The Role of Global and Feature Based Information in Gender Classification of Faces: A Comparison of Human Performance and Computational Models
Peer reviewe
Gender classification of face images: the role of global and feature-based information
Peer reviewe
Synthesis of empty bacterial microcompartments, directed organelle protein incorporation, and evidence of filament-associated organelle movement
Compartmentalization is an important process, since it allows the segregation of metabolic activities and, in the era of synthetic biology, represents an important tool by which defined microenvironments can be created for specific metabolic functions. Indeed, some bacteria make specialized proteinaceous metabolic compartments called bacterial microcompartments (BMCs) or metabolosomes. Here we demonstrate that the shell of the metabolosome (representing an empty BMC) can be produced within E. coil cells by the coordinated expression of genes encoding structural proteins. A plethora of diverse structures can be generated by changing the expression profile of these genes, including the formation of large axial filaments that interfere with septation. Fusing GFP to PduC, PduD, or PduV, none of which are shell proteins, allows regiospecific targeting of the reporter group to the empty BMC. Live cell imaging provides unexpected evidence of filament-associated BMC movement within the cell in the presence of Pdu
Agglomeration and New Establishment Survival: A Mixed Hierarchical and Cross-Classified Model
Recent empirical studies in regional science and urban economics show that agglomeration economies may be one source of the uneven distribution of economic activities and economic growth across cities and regions. At the same time, the body of research into the importance of agglomeration economies for the performance of firms is still growing. Such development is necessary, as the theories that underlie agglomeration economies are microeconomic in nature, but still insufficiently understood. In this study, we focus on the determinants of survival among new establishments in the advanced producer services sector in the Netherlands. Employing a mixed hierarchical and cross-classified probit regression, we introduce a model of establishment survival that is specific to characteristics of the internal and external environment of the establishment. Controlling for firm and sector characteristics, we conclude that location accounts for about 4% of the variance in the probability of survival of new establishments. We also find that localization and urbanization economies have a positive effect on the survival of new establishments. However, new establishments with large start-up sizes appear to profit more from agglomeration economies than new establishments with small start-up sizes
On the Economic Foundation of the Urban Network Paradigm: Spatial Integration, Functional Integration and Economic Complementarities within the Dutch Randstad
The current debate on polycentric urban development suggests that inter-firm relations are important for the creation and sustainment of urban networks. Conceptually, the degrees of spatial and functional integration and urban complementarities in economic network relations are hypothesised to be important. However, the theoretical economic rationale has not been convincingly tested. In this paper, we use data on inter-firm relations in the Dutch Randstad to test conditions for integration and the existence of economic complementarities within this region. Contrary to the ‘polycentricity hypothesis’, we observe a clear hierarchy in the different types of spatial interdependencies in the Randstad, in which the central place model prevails. Furthermore, we do not find evidence for the functional integration of municipalities in the Randstad. We conclude that at this moment the Randstad does not function as a spatially and functionally integrated region, and that spatial economic policy can better focus on smaller regions within the Randstad when urban economic complementarities and integration are desired. This also calls into question the applicability of the urban network concept in general, as the Dutch Randstad is usually seen as a prime example of an economically successful polycentric urban system
House Prices, Bubbles and City Size
We build a theoretical model that relates house price, city size and the expected future growth of demand for housing. Our model combines the Alonso-Mills model on urban economics with insights from financial economics on house prices. Estimating the model for cities in the US, we empirically validate the positive effect of city size on urban house prices. Moreover, our estimations confirm that an (unrealistic) increase in the expected growth of demand fuelled by the widespread availability of credit provides a better explanation for the recent bubble than inelastic housing supply that explained earlier bubbles
Heterogeneous relatedness and firm productivity
In this manuscript, we relate regional structural composition—related and unrelated variety—to firm-level productivity in European regions, applying a Cobb–Douglas production function framework and using firm-, industry- and regional-level mixed hierarchical (multilevel) models. Our analyses indicate that regional-related variety has a positive impact on firm productivity in European regions, especially for firms in high-tech and medium-tech regions. These outcomes have implications for European policies on competitiveness as firms embedded in regions without these technological and institutional circumstances are systematically worse off in terms of productivity, and catching-up is not obvious for such regional economies
Heterogeneous relatedness and firm productivity
In this manuscript, we relate regional structural composition—related and unrelated
variety—to frm-level productivity in European regions, applying a Cobb–Douglas
production function framework and using frm-, industry- and regional-level mixed
hierarchical (multilevel) models. Our analyses indicate that regional-related variety
has a positive impact on frm productivity in European regions, especially for frms
in high-tech and medium-tech regions. These outcomes have implications for European policies on competitiveness as frms embedded in regions without these technological and institutional circumstances are systematically worse of in terms of
productivity, and catching-up is not obvious for such regional economies
Electromagnetic Form Factors of Charged and Neutral Kaons
The charged and neutral kaon form factors are calculated as a
phenomenological application of the QCD Dyson-Schwinger equations. The results
are compared with the pion form factor calculated in the same framework and
yield \mbox{} on
\mbox{~GeV}; and a neutral kaon form factor that is similar in
form and magnitude to the neutron charge form factor. These results are
sensitive to the difference between the kaon and pion Bethe-Salpeter amplitude
and the - and -quark propagation characteristics.Comment: 11 Pages, 2 figures, REVTEX, uses epsfig. No chang
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