Government expenditures and unemployment: A DSGE perspective

In a New Keynesian DSGE model with labor market frictions and liquidity-constrained consumers aggregate unemployment is likely to increase due to a non-persistent government spending shock. Furthermore, the group of asset-holding households reacts very differently from the group of liquidity-constrained consumers implying that the unemployment rate is likely to decrease for asset-holding households, while it increases among liquidity-constrained consumers. The main driver of our results is the marginal utility of consumption which moves in opposite directions for the two types. Regarding the model's parameters, we find that the size of the fiscal (unemployment) multiplier increases with i) highly sticky prices, ii) high degrees of risk aversion, iii) low convexity in labor disutility iv) high replacement rates, and v) debt-financed expenditures. --Search and matching,government spending shocks,unemployment.

Clinical review: Medication errors in critical care

Medication errors in critical care are frequent, serious, and predictable. Critically ill patients are prescribed twice as many medications as patients outside of the intensive care unit (ICU) and nearly all will suffer a potentially life-threatening error at some point during their stay. The aim of this article is to provide a basic review of medication errors in the ICU, identify risk factors for medication errors, and suggest strategies to prevent errors and manage their consequences

Spatial and temporal control of Archean tectonomagmatic regimes

Secular trends in plutonic whole-rock geochemistry pose critical, although non-unique, constraints to early Earth tectonics. Here, we present a large whole-rock geochemical (879 collated samples) dataset for granitoids from the Pilbara Craton, Western Australia, applying it to test the link between secular trends and proposed tectonic mechanisms. We show that the spatio-temporal distribution of granitoid trace element geochemistry is constrained within discrete lithotectonic blocks supporting the reconstruction of its tectonomagmatic evolution. Time-sliced geochemical contour mapping of key petrogenetic ratios indicates the craton underwent rifting ∼3.2 Ga (billion years ago), marking a transition from predominantly sodic magmatism to a broader magmatic compositional spectrum. Our results demonstrate that rift-assisted breakup of proto-cratons is a viable craton growth mechanism. We identify a possible evolutionary sequence beginning with drips and upwellings below a Paleoarchean mafic plateau, which is subsequently dismembered by rifting. These plateau fragments form rigid blocks in the Mesoarchean, between which weaker, thinner crust accommodates minor convergence and divergence manifested as short-lived mobile lid-like features before stabilization. We conclude that these features do not require an active lid, plate tectonic regime

The stability of cratons is controlled by lithospheric thickness, as evidenced by Rb-Sr overprint ages in granitoids

The ancient cores of modern continents, cratons, are the oldest blocks of “stable” lithosphere on Earth. Their long-term survival relies on the resistance of their underlying thick, strong, and buoyant mantle keels to subsequent recycling. However, the effect of substantial geographical variations in keel thickness on the post-assembly behaviour and mass movement within these continental cores remains unknown. Here, we demonstrate that the spatial distribution of fluid-reset in-situ Rb-Sr ages for Paleo-Mesoarchean (3.6–2.8 billion years ago; Ga) granitoids of the Pilbara Craton, Australia shows remarkable correlation with independently-constrained lithospheric thickness models. Without craton-wide heating/magmatic events, these anomalously young Rb-Sr ages document episodes of fluid infiltration into granitoid complexes as a response to lithospheric reactivation by far-field stresses. This correlation implies that craton-wide fluid mobilization triggered by extra-cratonic Neoarchean to Mesoproterozoic (2.8–1.0 Ga) tectonic events is facilitated by variations in lithospheric strength and thickness. Compared to areas of older overprints, the two-thirds of the craton comprised of younger reset ages is underlain by comparatively thin lithosphere with higher susceptibility to reactivation-assisted fluid flow. We propose that even the strongest, most pristine cratons are less stable and impermeable than previously thought, as demonstrated by the role of granitoid complexes and cratons as selective lithospheric “sponges” in response to minor tectonic forces. Therefore, variations in lithospheric thickness, likely attained before cratonization, exert a crucial control on billions of years of fluid movement, elemental redistribution and mineralization within ancient continental nuclei

Contrasting rift and subduction-related plagiogranites in the Jinshajiang ophiolitic mélange, southwest China, and implications for the Paleo-Tethys

The Jinshajiang ophiolitic mélange zone in southwest China represents a remnant of the eastern Paleo-Tethys Ocean. Field, geochronological and geochemical studies have identified two distinct suites of plagiogranites within the mélange, the Dongzhulin trondhjemite and Jiyidu tonalite, which represent rift and subduction settings, respectively, related to opening and closing of the ocean. SHRIMP U-Pb analysis on zircons extracted from the Dongzhulin trondhjemite yields a mean 206Pb/238U age of 347 ± 7 Ma. REE and isotopic characteristics suggest an origin from low pressure partial melting of an amphibolitic protolith. Highly variable Hf isotopic compositions for zircons from this body may indicate a heterogenous source involving both depleted mantle and enriched continental components. This, together with geologic relations, suggests formation near an embryonic spreading center in a continent-ocean transition setting. The Jiyidu tonalite has a U-Pb zircon age of 283 ± 3 Ma, and geochemical data indicates high Sr/Y, (La/Yb)N, Nb/Ta and low Y, and marked heavy REE depletion. These signatures suggest derivation from low degree partial melting of subducted slab at pressure high enough to stabilize garnet and rutile. A slab-melt origin is also supported by in situ Hf and O data for zircon that show isotopic compositions comparable with typical altered oceanic crust. Thus, the crystallization age of the Jiyidu high Sr/Y tonalite provides a constraint for the subduction of the Jinshajiang ocean floor. The rift-related Dongzhulin trondhjemite and subduction-related Jiyidu high-Sr/Y tonalite constrain the timing and setting of opening and closing of this segment of the Paleo-Tethys Ocean

Conception et élaboration de substrats semiconducteurs nanostructurés : nouvelles applications en nanosciences

New nano-structured substrates being used as templates for the growth and study of nanoobjects were developed. Crystalline surfaces can naturally show regular patterns (reconstructions, superstructures, steps on vicinal surfaces...) but on scales not exceeding a few hundreds of nm2. However some physical measurements and the possible applications require large surfaces. New techniques were developed in order to create nano-structured surfaces on large scales, by imposing regular pattern with parallel processes. The obtained substrates were subsequently functionalized and could be used in various applications.In the case of vicinal surfaces of Si(111), the intrinsic crystallographic properties of silicon make it possible to obtain uni-dimensionnal patternd in the form of very regular, parallels and equidistant step-bunches. These patterns are functionalized by a subsequent gold deposition, forming uni-dimensional networks of monodisperse gold silicides dots, arranged according to the preexistant pattern, and separated by Si-rich terraces. After a cobalt deposition on such surfaces, only the dots have magnetic properties.In the case of silicon carbide (SiC) substrates, networks of several cm2 of faceted, vertical and hexagonally shaped nano-channels are obtained. The pattern of a porous alumina membrane is transferred by reactive ion etching on the SiC surface. Hydrogen etching at high temperature leads to the final faceted shape. An alternative technique based on the catalytic reaction of a platinium dots network with hydrogen makes it possible to obtain substrates of porous SiC at lower temperatures of erosion. These networks have potential applications in magnetism and biology.De nouveaux substrats nano-structurés servant de gabarits pour la croissance et l'étude des nano-objets ont été développées. Les surfaces cristallines peuvent présenter naturellement des motifs réguliers (reconstructions, sur-structures, marches sur des surfaces vicinales...) mais sur des échelles n'excédant pas quelques centaines de nm2. Or certaines mesures physiques et les éventuelles applications nécessitent de grandes aires. De nouvelles techniques ont été développéees afin de créer des surfaces nano-structurées sur de larges échelles, en leur imposant un motif régulier par des procédés parallèles. Les substrats ainsi obtenus ont par la suite été fonctionnalisées et ont pu être utilisés dans diverses applications.Dans le cas des surfaces vicinales de Si(111), les propriétés cristallographiques intrinsèques du silicium permettent d'obtenir des motifs uni-dimensionnels sous forme de paquets de marches très réguliers, parallèles entre eux et équidistants. Ces gabarits sont fonctionnalisés par un dépôt d'or formant des réseaux unidimensionnels de plots de siliciures d'or de taille monodisperse, arrangés selon le motif pré-existant, et séparés par des terrasses riches en silicium. Lors d'un dépôt de cobalt sur de telles surfaces, seuls les plots possèdent des propriétés magnétiques.Dans le cas du carbure de silicium (SiC), des réseaux de plusieurs cm2 de nano-canaux facettés, verticaux et de formes hexagonales sont crées par plusieurs méthodes. Le motif d'une membrane d'alumine poreuse est transféré par gravure ionique réactive sur la surface du SiC. Une érosion sous hydrogène à haute température donne aux pores leur forme facettée finale. Une technique alternative basée sur la réaction catalytique d'un réseau de plots de platine avec de l'hydrogène permet d'obtenir des substrats de SiC poreux à de basses températures d'érosion. Ces réseaux ont des applications potentielles dans le magnétisme et la biologie

Frank L. McVey and the University of Kentucky: A Progressive President and the Modernization of a Southern University

In 1917, fifty-two years after its founding, the University of Kentucky faced stagnation, financial troubles, and disturbing reports of nepotism, resulting in a leadership crisis. A special committee investigated the institution and issued a report calling for a massive transformation of the university, including the hiring of a new president who could execute the report\u27s suggested initiatives. The Board of Trustees hired Frank L. McVey. McVey labored tirelessly for more than two decades to establish Kentucky as one of the nation\u27s most respected institutions of higher learning, which brought him recognition as one of the leading progressive educators in the South. This book chronicles McVey\u27s triumphs and challenges as the president sought to transform the university from a small state college into the state\u27s flagship institution. McVey recruited an exceptional faculty, expanded graduate programs, promoted research, oversaw booming enrollments and campus construction, and defended academic freedom during the nation\u27s first major antievolution controversy. Yet he faced challenges related to the development of modern collegiate athletics, a populace suspicious of his remarkable new conception of a state university, and the Great Depression.https://uknowledge.uky.edu/upk_united_states_history/1184/thumbnail.jp

LES MESURES SUR RADIOGRAPHIES PLANES ET TRIDIMENSIONNELLES EN ORTHOPEDIE (APPLICATIONS CLINIQUES (DOCTORAT : GENIE BIOLOGIQUE ET MEDICAL))

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