A Literature Review of Social and Economic Leader-Member Exchange

Leader–member exchange (LMX) research has increasingly relied upon the social exchange theory (SET) as a theoretical foundation, but the dominating way of measuring LMX has not followed this theoretical development (Gottfredson et al., 2020). With the aim of developing a measure that more coherently reflects SET, Kuvaas et al. (2012) conceptualized LMX as two qualitatively different relationships, labeled economic LMX and social LMX. Since the most applied LMX measures are under scrutiny for not being sufficiently grounded in theory (Gottfredson et al., 2020), it may be especially important to expose alternative measures. Therefore, we provide a comprehensive review of the research to date applying a two-dimensional approach to LMX, while also adding to interpretation and suggestions for how we can progress the field even further.publishedVersio

Determinación de la relación entre la comunicación y el liderazgo en la aceptación del cambio organizacional en un ambiente universitario en la ciudad de Bogotá.

Trabajo de investigaciónEl objetivo fue determinar con un diseño cuantitativo correlacional la interacción entre comunicación y liderazgo con el cambio organizacional en una universidad de Bogotá. Se realizó bajo un estudio no experimental transversal donde participaron 62 trabajadores de una universidad. Se aplicó el instrumento Medición de Cambio (IMC), el cuestionario de Comunicación Organizacional (CCO) y el cuestionario adaptado de Liderazgo Multifactorial versión Líder (Multifactor Leadership Questionnaire MLQ). No se encontró una relación significativa entre las habilidades de liderazgo de los participantes y el cambio organizacional. En la relación del cambio organizacional con la comunicación se observa una correlación positiva con las variables de comunicación, especialmente en el trabajo en equipo, el intercambio de información y la comunicación entre pares.MaestríaMagister en Psicologí

A super Asian dust storm over the East and South China Seas: disproportionate dust deposition

A super Asian dust (SAD) storm that originated from North China has affected East Asia since 20 March 2010. The tempo-spatial and size distributions of aerosol Al, a tracer of wind-blown dust, were measured on a regional aerosol network in March 2010. Two dust events were recorded: the SAD and a relatively moderate AD event. The SAD clouds raised Al concentrations to ~50 µg/m3 on 21 and 22 March over the East China Sea (ECS) and occupied there for ~5 days. The SAD plume also stretched toward the South China Sea (SCS) on 21 March however, it caused a maximum Al concentration of ~8.5 µg/m3 only, much lower than that observed in the ECS. In comparison, a weaker dust plume on 16 March caused Al maximum of ~4 µg/m3 over the ECS, and comparably, ~3 µg/m3 in the SCS. Dry dust deposition was measured during the peak phase of the SAD at 178 mg/m2/d, which corresponded to dry deposition velocities of 0.2–0.6 cm/s only, much lower than the commonly adopted one (1–2 cm/s). The corresponding increase in dust deposition by the SAD was up to a factor of ~12, which was, however, considerably disproportionate to the increase in dust concentration (i.e., the factor of over 100). In certain cases, synoptic atmospheric conditions appear to be more important in regulating dust contribution to the SCS than the strength of AD storms

The role of atmospheric deposition in the biogeochemistry of the Mediterranean Sea

Estimates of atmospheric inputs to the Mediterranean (MED) and some coastal areas are reviewed, and uncertainities in these estimates considered. Both the magnitude and the mineralogical composition of atmospheric dust inputs indicate that eolian deposition is an important (50%) or prevailing (>80%) contribution to sediments in the offshore waters of the entire Mediterranean (MED) basin. Model data for trace metals and nutrients indicate that the atmosphere delivers more than half the lead and nitrogen, one-third of total phosphorus, and 10% of the zinc entering the entire basin. Measured data in sub-basins, such as the north-western MED and northern Adriatic indicate an even greater proportion of atmospheric versus riverine inputs. When dissolved fluxes are compared (the form most likely to impinge on surface water biogeochemical cycles), the atmosphere is found to be 5 to 50 times more important than rivers for dissolved Zn and 15 to 30 times more important for Pb fluxes. Neglecting co-limitation by other nutrients, new production supported by atmospheric nitrogen deposition ranges from 2-4 g C m-2 yr-1, whereas atmospheric phosphorus deposition appears to support less than 1 g C m-2 yr-1. In spite of the apparently small contribution of atmospheric deposition to overall production in the basin it has been suggested that certain episodes of phytoplankton blooms are triggered by atmospheric deposition of N, P or Fe. Future studies are needed to clarify the extent and causal links between these episodic blooms and atmospheric/oceanographic forcing functions. A scientific program aimed at elucidating the possible biogeochemical effects of Saharan outbreaks in the MED through direct sampling of the ocean and atmosphere before and after such events is therefore highly recommended

Nature, extent and ecological implications of night-time light from road vehicles

This is the author accepted manuscript. The final version is available from Wiley via the DOI in this record1.The erosion of night‐time by the introduction of artificial lighting constitutes a profound pressure on the natural environment. It has altered what had for millennia been reliable signals from natural light cycles used for regulating a host of biological processes, with impacts ranging from changes in gene expression to ecosystem processes. 2.Studies of these impacts have focused almost exclusively on those resulting from stationary sources of light emissions, and particularly streetlights. However, mobile sources, especially road vehicle headlights, contribute substantial additional emissions. 3.The ecological impacts of light emissions from vehicle headlights are likely to be especially high because these are (i) focused so as to light roadsides at higher intensities than commonly experienced from other sources, and well above activation thresholds for many biological processes; (ii) projected largely in a horizontal plane and thus can carry over long distances; (iii) introduced into much larger areas of the landscape than experience street lighting; (iv) typically broad ‘white’ spectrum, which substantially overlaps the action spectra of many biological processes; and (v) often experienced at roadsides as series of pulses of light (produced by passage of vehicles), a dynamic known to have major biological impacts. 4.The ecological impacts of road vehicle headlights will markedly increase with projected global growth in numbers of vehicles and the road network, increasing the local severity of emissions (because vehicle numbers are increasing faster than growth in the road network) and introducing emissions into areas from which they were previously absent. The effects will be further exacerbated by technological developments that are increasing the intensity of headlight emissions and the amounts of blue light in emission spectra. 5.Synthesis and applications. Emissions from vehicle headlights need to be considered as a major, and growing, source of ecological impacts of artificial night‐time lighting. It will be a significant challenge to minimize these impacts whilst balancing drivers’ needs at night and avoiding risk and discomfort for other road users. Nonetheless, there is potential to identify solutions to these conflicts, both through the design of headlights and that of roads.The research leading to this article has received funding from the European Research Council under the European Union’s Seventh Framework Programme (FP7/2007-2013)/ERC grant agreement no. 268504 and Natural Environment Research Council grants NE/N001672/1 and NE/P01156X/1

Développement d’un biocapteur au sulfure d’hydrogène

Beyond its poisonous, corrosive, flammable and rotten odor properties, hydrogen sulfide (H2S) has recently been found to be a major gaseous transmitter in humans, in the same way as nitric oxide and carbon monoxide. Accurate detection of the low H2S concentrations present in biological media with an analytical tool, exhibiting appropriate sensitivity and specificity, is however still missing, restricting thus the characterization of the biological role of H2S and its possible involvement in pathologies. In this context, we propose here an innovative opto-electrochemical biosensor that combines the high specificity and affinity of a H2S-bioreceptor probe with the sensitivity of a 3D transparent metal oxide electrode. Our interest has notably been focused on a peculiar H2S-sensitive hemoprotein, the hemoglobin I (HbI) which, on account of its original heme pocket organization, shows particularly high specificity and affinity binding towards H2S. Upon reversible coordination of H2S to the ferric heme center, variations in the spectroscopic and electrochemical features of the protein offer original real-time, specific and sensitive H2S monitoring. To develop our biosensor, we decided to take advantage of a transparent and fully conductive mesoporous metal-oxide electrode based on ITO (indium tin oxide) which preparation by glancing angle vapor deposition - GLAD allows for excellent control of the morphology (film thickness and porosity) and reproducibility. This three-dimensional matrix allows for adsorption of large amounts of biological molecules without significant denaturation and up to a concentration easily detected by spectroscopy, as well as direct electron transfer in some cases. In order to prepare stable modified nanostructured electrodes, we have explored a two-steps covalent functionalization of the ITO surface by first introducing carboxyl functional groups by electrochemical reduction of in-situ generated diazonium salts, followed by covalent peptidic coupling of the hemoglobin I through the surface-accessible lysine residues. The resulting hemoglobin I-modified electrodes were characterized by different techniques. They exhibit excellent stability in solution, even in high ionic strength aqueous solutions. We further demonstrated that reversible H2S fixation can be monitored by simple UV-visible absorption spectroscopy, with excellent affinity and real time detection in the micromolar range. Furthermore, the high selectivity compared to other biological thiols (cysteine, glutathione) allows multiple biosensor application, hence achieving the device valorization.Au-delà de son caractère polluant, hautement toxique et son odeur d'oeuf pourri il est désormais démontré que le sulfure d'hydrogène, H2S, est également un transmetteur gazeux chez les mammifères aussi important que le monoxyde d'azote et le monoxyde de carbone. Cependant, et malgré de nombreuses avancées récentes, il n'existe toujours pas d'outils analytiques permettant une détection sensible, spécifique et en temps réel du sulfure d'hydrogène dans les milieux biologiques. Un tel dispositif permettrait notamment de valider l'implication d'H2S dans certaines pathologies, ouvrant ainsi la voie à une utilisation pharmacologique de cette molécule. Nous proposons dans ce travail de doctorat de développer un biocapteur opto-électrochimique innovant, combinant l'extrême affinité et spécificité d'une sonde biologique avec la sensibilité d'une électrode d'oxyde métallique, 3D et transparente. Pour cela, notre attention s'est portée sur une hémoglobine particulière, l'hémoglobine I (HbI), qui présente à travers l'organisation et la composition originale de la poche de l'hème, une affinité et une spécificité de liaison avec H2S très favorable. Les variations des propriétés spectroscopiques et électrochimiques de la protéine induites par la coordination d'H2S au centre ferrique de l'hème, permettent une détection originale en temps réel, sensible et spécifique du H2S. Pour développer ce biocapteur, nous avons tiré parti d'électrodes mésoporeuses conductrices et transparentes constituées d'oxyde d'indium dopé à l'étain (ITO), préparées par méthode de déposition physique (GLAD - GLancing Angle Deposition) offrant un excellent contrôle de la morphologie du film mésoporeux (épaisseur et porosité du film) et excellente reproductibilité. La tri-dimensionnalitée du réseau GLAD ITO permet l'immobilisation non dénaturante, d'une grande quantité biomolécules, facilitant la détection spectroscopique ainsi que, dans certains cas, un transfert d'électron direct. Pour la modification des électrodes nanostructurées, nous avons développé une méthodologie en deux étapes, avec d'une part l'introduction de fonctions carboxyles par réduction électrochimique in situ de sels d'aryldiazoniums puis un couplage peptidique de l'hémoglobine I avec les amines primaires des résidus lysines de surface. Les électrodes GLAD ITO/HbI modifiées ont par la suite été caractérisées par différentes techniques. Leurs stabilités en solution aqueuse, même à des forces ioniques élevées, est excellente. De plus nous avons démontré que la fixation rapide, réversible et sélective d'H2S à HbI immobilisée peut être suivie par simple spectroscopie d'absorption UV-visible ouvrant la voie à des analyses en temps réel. L'affinité pour H2S de l'électrode modifiée, de l'ordre du micromolaire et la spécificité du biocapteur vis-à-vis des autres thiols biologiques (cystéine, glutathion) permettent d'envisager de multiples applications valorisant ainsi le dispositif développé

Hydrogen sulfide biosensor

Au-delà de son caractère polluant, hautement toxique et son odeur d'oeuf pourri il est désormais démontré que le sulfure d'hydrogène, H2S, est également un transmetteur gazeux chez les mammifères aussi important que le monoxyde d'azote et le monoxyde de carbone. Cependant, et malgré de nombreuses avancées récentes, il n'existe toujours pas d'outils analytiques permettant une détection sensible, spécifique et en temps réel du sulfure d'hydrogène dans les milieux biologiques. Un tel dispositif permettrait notamment de valider l'implication d'H2S dans certaines pathologies, ouvrant ainsi la voie à une utilisation pharmacologique de cette molécule. Nous proposons dans ce travail de doctorat de développer un biocapteur opto-électrochimique innovant, combinant l'extrême affinité et spécificité d'une sonde biologique avec la sensibilité d'une électrode d'oxyde métallique, 3D et transparente. Pour cela, notre attention s'est portée sur une hémoglobine particulière, l'hémoglobine I (HbI), qui présente à travers l'organisation et la composition originale de la poche de l'hème, une affinité et une spécificité de liaison avec H2S très favorable. Les variations des propriétés spectroscopiques et électrochimiques de la protéine induites par la coordination d'H2S au centre ferrique de l'hème, permettent une détection originale en temps réel, sensible et spécifique du H2S. Pour développer ce biocapteur, nous avons tiré parti d'électrodes mésoporeuses conductrices et transparentes constituées d'oxyde d'indium dopé à l'étain (ITO), préparées par méthode de déposition physique (GLAD - GLancing Angle Deposition) offrant un excellent contrôle de la morphologie du film mésoporeux (épaisseur et porosité du film) et excellente reproductibilité. La tri-dimensionnalitée du réseau GLAD ITO permet l'immobilisation non dénaturante, d'une grande quantité biomolécules, facilitant la détection spectroscopique ainsi que, dans certains cas, un transfert d'électron direct. Pour la modification des électrodes nanostructurées, nous avons développé une méthodologie en deux étapes, avec d'une part l'introduction de fonctions carboxyles par réduction électrochimique in situ de sels d'aryldiazoniums puis un couplage peptidique de l'hémoglobine I avec les amines primaires des résidus lysines de surface. Les électrodes GLAD ITO/HbI modifiées ont par la suite été caractérisées par différentes techniques. Leurs stabilités en solution aqueuse, même à des forces ioniques élevées, est excellente. De plus nous avons démontré que la fixation rapide, réversible et sélective d'H2S à HbI immobilisée peut être suivie par simple spectroscopie d'absorption UV-visible ouvrant la voie à des analyses en temps réel. L'affinité pour H2S de l'électrode modifiée, de l'ordre du micromolaire et la spécificité du biocapteur vis-à-vis des autres thiols biologiques (cystéine, glutathion) permettent d'envisager de multiples applications valorisant ainsi le dispositif développé.Beyond its poisonous, corrosive, flammable and rotten odor properties, hydrogen sulfide (H2S) has recently been found to be a major gaseous transmitter in humans, in the same way as nitric oxide and carbon monoxide. Accurate detection of the low H2S concentrations present in biological media with an analytical tool, exhibiting appropriate sensitivity and specificity, is however still missing, restricting thus the characterization of the biological role of H2S and its possible involvement in pathologies. In this context, we propose here an innovative opto-electrochemical biosensor that combines the high specificity and affinity of a H2S-bioreceptor probe with the sensitivity of a 3D transparent metal oxide electrode. Our interest has notably been focused on a peculiar H2S-sensitive hemoprotein, the hemoglobin I (HbI) which, on account of its original heme pocket organization, shows particularly high specificity and affinity binding towards H2S. Upon reversible coordination of H2S to the ferric heme center, variations in the spectroscopic and electrochemical features of the protein offer original real-time, specific and sensitive H2S monitoring. To develop our biosensor, we decided to take advantage of a transparent and fully conductive mesoporous metal-oxide electrode based on ITO (indium tin oxide) which preparation by glancing angle vapor deposition - GLAD allows for excellent control of the morphology (film thickness and porosity) and reproducibility. This three-dimensional matrix allows for adsorption of large amounts of biological molecules without significant denaturation and up to a concentration easily detected by spectroscopy, as well as direct electron transfer in some cases. In order to prepare stable modified nanostructured electrodes, we have explored a two-steps covalent functionalization of the ITO surface by first introducing carboxyl functional groups by electrochemical reduction of in-situ generated diazonium salts, followed by covalent peptidic coupling of the hemoglobin I through the surface-accessible lysine residues. The resulting hemoglobin I-modified electrodes were characterized by different techniques. They exhibit excellent stability in solution, even in high ionic strength aqueous solutions. We further demonstrated that reversible H2S fixation can be monitored by simple UV-visible absorption spectroscopy, with excellent affinity and real time detection in the micromolar range. Furthermore, the high selectivity compared to other biological thiols (cysteine, glutathione) allows multiple biosensor application, hence achieving the device valorization