How is service procurement different from goods procurement? Exploring ex ante costs and ex post problems in IT procurement

Several studies suggest that, in practice, service procurement is more challenging than goods procurement. The underlying but largely implicit argument is that the procurement process for services involves higher buyer uncertainty and therefore requires extra efforts to mitigate this uncertainty. Drawing on Transaction Cost Economics, we use a database of information technology transactions to investigate the relationship between transaction characteristics and social embeddedness, and ex ante cost and ex post problems. We explore whether the same relationships hold across transactions that involve only goods versus transactions that also involve services. Our findings support conventional wisdom that managing the procurement process for transactions involving services is more challenging than for transactions involving goods. However, when controlling for typical transaction characteristics, there is no difference between transactions involving goods and transactions that also involve services

Stochastic Blockmodeling for the Analysis of Big Data

The aim of this paper is to consider the stochastic blockmodel to obtain clusters of units as regards patterns of similar relations; moreover we want to analyze the relations between clusters. Blockmodeling is a technique usually applied in social network analysis focusing on the relations between \u201cactors\u201d i.e. units. In our time people and devices constantly generate data. The network is generating location and other data that keeps services running and ready to use in every moment. This rapid development in the availability and access to data has induced the need for better analysis techniques to understand the various phenomena. Blockmodeling techniques and Clustering algorithms, can be used for this aim. In this paper application regards the Web

Structure of the triplet excited state of bromanil from time-resolved resonance Raman spectra and simulation

Time-resolved resonance Raman (TR3) spectroscopy has been used to study the structure of the triplet excited state of bromanil. These experimental results were then simulated using parameters from density functional theoretical (DFT) calculations and wave packet dynamics, in order to understand the structure and mode-specific displacements of the resonant excited state. The transition dipole moments and the energy separation of the T1 and Tn states were obtained from time-dependent DFT calculations. We have demonstrated application of the technique to tetrabromo-p-benzoquinone. From our calculations, the observed T1->Tn absorption spectrum has been assigned to the 3Bg→3Bu transition. The geometry has been optimized for the resonant higher triplet state, Tn, and is found to be in good agreement with the predictions of the wave packet dynamical simulations. Mode-specific displacements of the triplet state geometry have been obtained from simulations and these have been rationalized with respect to the molecular orbital involved. Thus, we have demonstrated that from the simulations of the experimental TR3 spectral data, valuable additional information can be derived on the structure of the transient states that may then be used for elucidation of structure-reactivity correlation in the future

A discrete solvent reaction field model for calculating frequency-dependent hyperpolarizabilities of molecules in solution

We present a discrete solvent reaction field (DRF) model for the calculation of frequency-dependent hyperpolarizabilities of molecules in solution. In this model the solute is described using density functional theory (DFT) and the discrete solvent molecules are described with a classical polarizable model. The first hyperpolarizability is obtained in an efficient way using time-dependent DFT and the (2n+1) rule. The method was tested for liquid water using a model in which a water molecule is embedded in a cluster of 127 classical water molecules. The frequency-dependent first and second hyperpolarizabilities related to the electric field induced second harmonic generation (EFISH) experiment, were calculated both in the gas phase and in the liquid phase. For water in the gas phase, results are obtained in good agreement with correlated wave function methods and experiments by using the so-called shape-corrected exchange correlation (xc)-potentials. In the liquid phase the effect of using asymptotically correct functionals is discussed. The model reproduced the experimentally observed sign change in the first hyperpolarizaibility when going from the gas phase to the liquid phase. Furthermore, it is shown that the first hyperpolarizability is more sensitive to damping of the solvent-solute interactions at short range than the second hyperpolarizability. (C) 2003 American Institute of Physics

Analysis of Signaling Endosome Composition and Dynamics Using SILAC in Embryonic Stem Cell-Derived Neurons

Neurons require efficient transport mechanisms such as fast axonal transport to ensure neuronal homeostasis and survival. Neurotrophins and their receptors are conveyed via fast axonal retrograde transport of signaling endosomes to the soma, where they elicit transcriptional responses. Despite the essential roles of signaling endosomes in neuronal differentiation and survival, little is known about their molecular identity, dynamics, and regulation. Gaining a better mechanistic understanding of these organelles and their kinetics is crucial, given the growing evidence linking vesicular trafficking deficits to neurodegeneration. Here, we exploited an affinity purification strategy using the binding fragment of tetanus neurotoxin (HCT) conjugated to monocrystalline iron oxide nanoparticles (MIONs), which in motor neurons, is transported in the same carriers as neurotrophins and their receptors. To quantitatively assess the molecular composition of HCT-containing signaling endosomes, we have developed a protocol for triple Stable Isotope Labeling with Amino acids in Cell culture (SILAC) in embryonic stem cell-derived motor neurons. After HCT internalization, retrograde carriers were magnetically isolated at different time points and subjected to mass-spectrometry and Gene Ontology analyses. This purification strategy is highly specific, as confirmed by the presence of essential regulators of fast axonal transport in the make-up of these organelles. Our results indicate that signaling endosomes undergo a rapid maturation with the acquisition of late endosome markers following a specific time-dependent kinetics. Strikingly, signaling endosomes are specifically enriched in proteins known to be involved in neurodegenerative diseases and neuroinfection. Moreover, we highlighted the presence of novel components, whose precise temporal recruitment on signaling endosomes might be essential for proper sorting and/or transport of these organelles. This study provides the first quantitative proteomic analysis of signaling endosomes isolated from motor neurons and allows the assembly of a functional map of these axonal carriers involved in long-range neuronal signaling

Overcoming the challenges of cancer drug resistance through bacterial-mediated therapy.

Despite tremendous efforts to fight cancer, it remains a major public health problem and a leading cause of death worldwide. With increased knowledge of cancer pathways and improved technological platforms, precision therapeutics that specifically target aberrant cancer pathways have improved patient outcomes. Nevertheless, a primary cause of unsuccessful cancer therapy remains cancer drug resistance. In this review, we summarize the broad classes of resistance to cancer therapy, particularly pharmacokinetics, the tumor microenvironment, and drug resistance mechanisms. Furthermore, we describe how bacterial-mediated cancer therapy, a bygone mode of treatment, has been revitalized by synthetic biology and is uniquely suited to address the primary resistance mechanisms that confound traditional therapies. Through genetic engineering, we discuss how bacteria can be potent anticancer agents given their tumor targeting potential, anti-tumor activity, safety, and coordinated delivery of anti-cancer drugs

Employment insecurity and life satisfaction: The moderating influence of labour market policies across Europe

This article tests whether the link between employment insecurity and life satisfaction is moderated by the generosity of labour market policies across Europe. Employment insecurity provokes anxieties about (a) the difficulties of finding a new job and (b) alternative sources of non-work income. These components can be related to active and passive labour market policies, respectively. Generous policy support is thus expected to buffer the negative consequences of employment insecurity by lowering the perceived difficulty of finding a similar job or providing income maintenance during unemployment. Based on data for 22 countries from the 2010 European Social Survey, initial support for this hypothesis is found. Perceived employment insecurity is negatively associated with life satisfaction but the strength of the relationship is inversely related to the generosity of labour market policies. Employment insecurity, in other words, is more harmful in countries where labour market policies are less generous