Topic modeling applied to business research: A latent dirichlet allocation (LDA)-based classification for organization studies

More than 1.5 million academic documents are published each year, and this trend shows an incremental tendency for the following years. One of the main challenges for the academic community is how to organize this huge volume of documentation to have a sense of the knowledge frontier. In this study we applied Latent Dirichlet Allocation (LDA) techniques to identify primary topics in organization studies, and analyzed the relationships between academic impact and belonging to the topics detected by LDA

Climate Dynamics: A Network-Based Approach for the Analysis of Global Precipitation

Precipitation is one of the most important meteorological variables for defining the climate dynamics, but the spatial patterns of precipitation have not been fully investigated yet. The complex network theory, which provides a robust tool to investigate the statistical interdependence of many interacting elements, is used here to analyze the spatial dynamics of annual precipitation over seventy years (1941-2010). The precipitation network is built associating a node to a geographical region, which has a temporal distribution of precipitation, and identifying possible links among nodes through the correlation function. The precipitation network reveals significant spatial variability with barely connected regions, as Eastern China and Japan, and highly connected regions, such as the African Sahel, Eastern Australia and, to a lesser extent, Northern Europe. Sahel and Eastern Australia are remarkably dry regions, where low amounts of rainfall are uniformly distributed on continental scales and small-scale extreme events are rare. As a consequence, the precipitation gradient is low, making these regions well connected on a large spatial scale. On the contrary, the Asiatic South-East is often reached by extreme events such as monsoons, tropical cyclones and heat waves, which can all contribute to reduce the correlation to the short-range scale only. Some patterns emerging between mid-latitude and tropical regions suggest a possible impact of the propagation of planetary waves on precipitation at a global scale. Other links can be qualitatively associated to the atmospheric and oceanic circulation. To analyze the sensitivity of the network to the physical closeness of the nodes, short-term connections are broken. The African Sahel, Eastern Australia and Northern Europe regions again appear as the supernodes of the network, confirming furthermore their long-range connection structure. Almost all North-American and Asian nodes vanish, revealing that extreme events can enhance high precipitation gradients, leading to a systematic absence of long-range patterns

Contribution of Distinct Homeodomain DNA Binding Specificities to Drosophila Embryonic Mesodermal Cell-Specific Gene Expression Programs

Homeodomain (HD) proteins are a large family of evolutionarily conserved transcription factors (TFs) having diverse developmental functions, often acting within the same cell types, yet many members of this family paradoxically recognize similar DNA sequences. Thus, with multiple family members having the potential to recognize the same DNA sequences in cis-regulatory elements, it is difficult to ascertain the role of an individual HD or a subclass of HDs in mediating a particular developmental function. To investigate this problem, we focused our studies on the Drosophila embryonic mesoderm where HD TFs are required to establish not only segmental identities (such as the Hox TFs), but also tissue and cell fate specification and differentiation (such as the NK-2 HDs, Six HDs and identity HDs (I-HDs)). Here we utilized the complete spectrum of DNA binding specificities determined by protein binding microarrays (PBMs) for a diverse collection of HDs to modify the nucleotide sequences of numerous mesodermal enhancers to be recognized by either no or a single subclass of HDs, and subsequently assayed the consequences of these changes on enhancer function in transgenic reporter assays. These studies show that individual mesodermal enhancers receive separate transcriptional input from both I–HD and Hox subclasses of HDs. In addition, we demonstrate that enhancers regulating upstream components of the mesodermal regulatory network are targeted by the Six class of HDs. Finally, we establish the necessity of NK-2 HD binding sequences to activate gene expression in multiple mesodermal tissues, supporting a potential role for the NK-2 HD TF Tinman (Tin) as a pioneer factor that cooperates with other factors to regulate cell-specific gene expression programs. Collectively, these results underscore the critical role played by HDs of multiple subclasses in inducing the unique genetic programs of individual mesodermal cells, and in coordinating the gene regulatory networks directing mesoderm development.National Institutes of Health (U.S.) (Grant R01 HG005287

Multifactorial Regulation of a Hox Target Gene

Hox proteins play fundamental roles in controlling morphogenetic diversity along the anterior–posterior body axis of animals by regulating distinct sets of target genes. Within their rather broad expression domains, individual Hox proteins control cell diversification and pattern formation and consequently target gene expression in a highly localized manner, sometimes even only in a single cell. To achieve this high-regulatory specificity, it has been postulated that Hox proteins co-operate with other transcription factors to activate or repress their target genes in a highly context-specific manner in vivo. However, only a few of these factors have been identified. Here, we analyze the regulation of the cell death gene reaper (rpr) by the Hox protein Deformed (Dfd) and suggest that local activation of rpr expression in the anterior part of the maxillary segment is achieved through a combinatorial interaction of Dfd with at least eight functionally diverse transcriptional regulators on a minimal enhancer. It follows that context-dependent combinations of Hox proteins and other transcription factors on small, modular Hox response elements (HREs) could be responsible for the proper spatio-temporal expression of Hox targets. Thus, a large number of transcription factors are likely to be directly involved in Hox target gene regulation in vivo

Protein misfolding and dysregulated protein homeostasis in autoinflammatory diseases and beyond.

Cells have a number of mechanisms to maintain protein homeostasis, including proteasome-mediated degradation of ubiquitinated proteins and autophagy, a regulated process of ‘self-eating’ where the contents of entire organelles can be recycled for other uses. The unfolded protein response prevents protein overload in the secretory pathway. In the past decade, it has become clear that these fundamental cellular processes also help contain inflammation though degrading pro-inflammatory protein complexes such as the NLRP3 inflammasome. Signaling pathways such as the UPR can also be co-opted by toll-like receptor and mitochondrial reactive oxygen species signaling to induce inflammatory responses. Mutations that alter key inflammatory proteins, such as NLRP3 or TNFR1, can overcome normal protein homeostasis mechanisms, resulting in autoinflammatory diseases. Conversely, Mendelian defects in the proteasome cause protein accumulation, which can trigger interferon-dependent autoinflammatory disease. In non-Mendelian inflammatory diseases, polymorphisms in genes affecting the UPR or autophagy pathways can contribute to disease, and in diseases not formerly considered inflammatory such as neurodegenerative conditions and type 2 diabetes, there is increasing evidence that cell intrinsic or environmental alterations in protein homeostasis may contribute to pathogenesis

The engineering labor market

This paper develops a dynamic supply and demand model of occupational choice and applies it to the engineering profession. The model is largely successful in understanding data in the U. S. engineering labor market. The engineering market responds strongly to economic forces. The demand for engineers responds to the price of engineering services and demand shifters. More important, supply and enrollment decisions are remarkably sensitive to career prospects in engineering. Also a rational model, in which students use some forward-looking elements to forecast future demand for engineers, fits the data reasonably well. These findings suggest that subsidies to build technical talent ahead of demand are misplaced unless public policy makers have better information on future market conditions than the market participants do

Cupric ion species in Cu(II)-exchanged K - offretite gallosilicate determined by electron spin resonance and electron spin echo modulation spectroscopies

The location of Cu(II) and its interaction with deuterated adsorbates in Cu(II)-exchanged gallosilicate with the offretite channel-type structure were investigated by electron spin resonance (ESR) and electron spin echo modulation (ESEM) spectroscopies. It is suggested that in fresh, hydrated offretite gallosilicate Cu(II) is in the main channel coordinated to three water molecules and three framework oxygens in a six-ring window of an epsilon-cage to form distorted octahedral coordination. Upon evacuation at increasing temperature, Cu(II) moves from the main channel through an epsilon-cage to a hexagonal prism, Dehydration at 400 degrees C produces one Cu(II) species located in a recessed site in a hexagonal prism based on a lack of broadening of its ESR lines by oxygen. Adsorption of polar molecules such as water, alcohols, dimethyl sulfoxide, and ammonia causes changes in the ESR spectrum of the Cu(II), indicating migration into cation positions in the main channels where adsorbate coordination can occur. However, nonpolar ethylene does nor cause migration of Cu(II). Cu(II) forms complexes with two molecules of methanol, ethanol, and propanol and one molecule of dimethyl sulfoxide based on ESEM data. Cu(II) is suggested to form a trigonal-bipyramidal complex with two ammonias in axial positions and three framework oxygens in a six-ring window of an epsilon-cage based on its ESR parameters and ESEM data.1112sciescopu

Copper(II) ionic species in Cu-II-exchanged K-offretite aluminosilicate and comparison with Cu-II-exchanged K-offretite gallosilicate determined by electron paramagnetic resonance and electron spin echo modulation spectroscopies

The location of Cu-II and its interaction with deuteriated adsorbates in Cu-II-exchanged K-offretite aluminosilicate zeolite have been investigated by electron paramagnetic resonance (EPR) and electron spin echo modulation (ESEM) spectroscopies and compared with those in Cu-II-exchanged K-offretite gallosilicate. Basically similar Cu-II locations to those in CuK-offretite gallosilicate are observed in CuK-offretite aluminosilicate, but there are some interesting differences. It is found that in the fresh hydrated sample, Cu-II is, in the main channel, coordinated to three water molecules and three framework oxygens in a six-ring window of an epsilon-cage to form a distorted octahedral complex. Upon evacuation at increasing temperature, Cu-II ions move from the main channel through the E-cages to hexagonal prism sites. However, the water coordinated to Cu-II is more tightly bound in the aluminosilicate than in the gallosilicate. Dehydration produces two different Cu-II species in the aluminosilicate, both believed to be located in recessed sites owing to the lack of broadening of its EPR lines by oxygen, while only one Cu-II species is located in a recessed site in the gallosilicate. Adsorption of polar molecules such as water, alcohols, dimethyl sulfoxide, acetonitrile and ammonia cause changes in the EPR spectrum of the Cu-II indicating migration into cation positions in the main channels where adsorbate coordination can occur. However, non-polar ethene does not cause migration of Cu-II. Cu-II forms complexes with two molecules of methanol, ethanol and propanol, and one molecule of dimethyl sulfoxide based on ESEM data. Cu-II forms a trigonal bipyramidal complex with two ammonias in axial positions and three framework oxygens in a six-ring window of an epsilon-cage based on EPR parameters and ESEM data, which is the same for Cu-II in CuK-offretite gallosilicate.open1110sciescopu