Prospects for Observing the low-density Cosmic Web in Lyman-alpha Emission

Mapping the intergalactic medium (IGM) in Lyman-$\alpha$ emission would yield unprecedented tomographic information on the large-scale distribution of baryons and potentially provide new constraints on the UV background and various feedback processes relevant to galaxy formation. Here, we use a cosmological hydrodynamical simulation to examine the Lyman-$\alpha$ emission of the IGM due to collisional excitations and recombinations in the presence of a UV background. We focus on gas in large-scale-structure filaments in which Lyman-$\alpha$ radiative transfer effects are expected to be moderate. At low density the emission is primarily due to fluorescent re-emission of the ionising UV background due to recombinations, while collisional excitations dominate at higher densities. We discuss prospects of current and future observational facilities to detect this emission and find that the emission of filaments of the cosmic web will typically be dominated by the halos and galaxies embedded in them, rather than by the lower density filament gas outside halos. Detecting filament gas directly would require a very long exposure with a MUSE-like instrument on the ELT. Our most robust predictions that act as lower limits indicate this would be slightly less challenging at lower redshifts ($z \lesssim 4$). We also find that there is a large amount of variance between fields in our mock observations. High-redshift protoclusters appear to be the most promising environment to observe the filamentary IGM in Lyman-$\alpha$ emission.Comment: 20 pages, 13 figures. Accepted for publication in Astronomy & Astrophysics. Accepted version contains several revisions following suggestions made in the review proces

Composition, distribution and supposed origin of mineral inclusions in sessile oak wood - consequences for microdensitometrical analysis

SEM and light-microscopical observations, supported by chemical microanalysis with an EDXA system, revealed that light-saturated pixels observed in X-ray negatives of sessile oak (Quercus petraea Liebl.) wood were caused by inorganic deposits present inside multiseriate ray and axial parenchyma cells. Calcium oxalate crystals, silica grains and amorphous granules with varied mineral compositions have been identified. The wood strips of three out of six sampled trees contained measurable amounts of mineral inclusions which were quantified using image analysis. Based on the variations of mineral content observed between trees and within and between annual rings of the same tree, some hypotheses were formulated concerning the factors involved in the formation of inorganic deposits in oak wood. Their occurrence varies depending on the mineral concerned and seems to be controlled largely by a tree effect. The time of formation appears to coincide with a shifting of the oak wood’s functions as a result of heartwood formation processes (inter-annual scale) or changes in leaf phenology and climate (intra-annual scale). In addition, the technical consequences of their presence as well as their effects on wood density measurements through microdensitometry are discussedComposition, distribution et origine supposée d’inclusions minérales dans le bois de chêne sessile – conséquences pour l’analyse microdensitométrique. Des observations à l’aide de microscopes électronique à balayage et optique, appuyées par des analyses élémentaires au moyen d’un système EDXA, ont révélé que les points-images saturés en niveau de gris, constatés dans les négatifs de radiographies de bois de chêne sessile (Quercus petraea Liebl.), étaient dus à des dépôts inorganiques présents à l’intérieur des cellules parenchymateuses des rayons ligneux multisériés et du parenchyme axial. Des cristaux d’oxalate de calcium, des grains de silice et des granules amorphes ayant des compositions minérales variées ont été identifiés. Des barrettes de trois sur six arbres échantillonnés contenaient des quantités mesurables d’inclusions minérales qui ont été quantifiées par analyse d’images. En se basant sur les variations du contenu en dépôts minéraux observées entre arbres ainsi qu’à l’intérieur d’un arbre, aux niveaux intra- et intercerne, quelques hypothèses ont été avancées concernant les facteurs potentiellement responsables de la formation de dépôts minéraux chez le chêne. Leur présence dépend du minéral concerné et semble être contrôlée par un fort effet arbre. L’apparition des minéraux coïncide apparemment avec des changements de fonctions du bois relatifs aux processus de duraminisation (échelle interannuelle) ou correspondant à des évolutions phénologiques ou climatiques (échelle intra-annuelle). Enfin, les conséquences techniques ainsi que les effets de leur présence sur des mesures de la densité du bois par analyse microdensitométrique sont discuté

The organizational dynamics enabling patient portal impacts upon organizational performance and patient health: a qualitative study of Kaiser Permanente.

BackgroundPatient portals may lead to enhanced disease management, health plan retention, changes in channel utilization, and lower environmental waste. However, despite growing research on patient portals and their effects, our understanding of the organizational dynamics that explain how effects come about is limited.MethodsThis paper uses qualitative methods to advance our understanding of the organizational dynamics that influence the impact of a patient portal on organizational performance and patient health. The study setting is Kaiser Permanente, the world's largest not-for-profit integrated delivery system, which has been using a portal for over ten years. We interviewed eighteen physician leaders and executives particularly knowledgeable about the portal to learn about how they believe the patient portal works and what organizational factors affect its workings. Our analytical framework centered on two research questions. (1) How does the patient portal impact care delivery to produce the documented effects?; and (2) What are the important organizational factors that influence the patient portal's development?ResultsWe identify five ways in which the patient portal may impact care delivery to produce reported effects. First, the portal's ability to ease access to services improves some patients' satisfaction as well as changes the way patients seek care. Second, the transparency and activation of information enable some patients to better manage their care. Third, care management may also be improved through augmented patient-physician interaction. This augmented interaction may also increase the 'stickiness' of some patients to their providers. Forth, a similar effect may be triggered by a closer connection between Kaiser Permanente and patients, which may reduce the likelihood that patients will switch health plans. Finally, the portal may induce efficiencies in physician workflow and administrative tasks, stimulating certain operational savings and deeper involvement of patients in medical decisions. Moreover, our analysis illuminated seven organizational factors of particular importance to the portal's development--and thereby ability to impact care delivery: alignment with financial incentives, synergy with existing IT infrastructure and operations, physician-led governance, inclusive decision making and knowledge sharing, regional flexibility to implementation, continuous innovation, and emphasis on patient-centered design.ConclusionsThese findings show how organizational dynamics enable the patient portal to affect care delivery by summoning organization-wide support for and use of a portal that meets patient needs