Credit Spreads as Predictors of Real-Time Economic Activity: A Bayesian Model-Averaging Approach

Employing a large number of real and financial indicators, we use Bayesian Model Averaging (BMA) to forecast real-time measures of economic activity. Importantly, the predictor set includes option-adjusted credit spread indexes based on bond portfolios sorted by maturity and credit risk as measured by the issuer’s “distance-to-default.” The portfolios are constructed directly from the secondary market prices of outstanding senior unsecured bonds issued by a large number of U.S. corporations. Our results indicate that relative to an autoregressive benchmark, BMA yields consistent improvements in the prediction of the growth rates of real GDP, business fixed investment, industrial production, and employment, as well as of the changes in the unemployment rate, at horizons from the current quarter (i.e., “nowcasting”) out to four quarters hence. The gains in forecast accuracy are statistically significant and economically important and owe exclusively to the inclusion of our portfolio credit spreads in the set of predictors—BMA consistently assigns a high posterior weight to models that include these financial indicators.

Ab initio determination of an extended Heisenberg Hamiltonian in CuO2 layers

Accurate ab initio calculations on embedded Cu_4O_{12} square clusters, fragments of the La_2CuO_4 lattice, confirm a value of the nearest neighbor antiferromagnetic coupling (J=124 meV) previously obtained from ab initio calculations on bicentric clusters and in good agreement with experiment. These calculations predict non negligible antiferromagnetic second-neighbor interaction (J'=6.5 meV) and four-spin cyclic exchange (K=14 meV), which may affect the thermodynamic and spectroscopic properties of these materials. The dependence of the magnetic coupling on local lattice distortions has also been investigated. Among them the best candidate to induce a spin-phonon effect seems to be the movement of the Cu atoms, changing the Cu-Cu distance, for which the variation of the nearest neighbor magnetic coupling with the Cu-O distance is {\Delta J}/{\Delta d_{Cu-O}}\sim 1700 cm^{-1} A^{-1}.Comment: 11 pages, 5 figures, submitted to Phys. Rev.

Experiences of physical activity during pregnancy resulting from in vitro fertilisation: an interpretative phenomenological analysis

Objective To explore the qualitative experiences and decision-making processes surrounding physical activity (PA) for women who have undergone IVF treatment. Background Physical activity (PA) during pregnancy is safe for both mother and fetus in the majority of cases, including for women who have undergone in vitro fertilisation (IVF) treatment; however, there is a paucity of research into decision-making and PA in this population. Methods Eight women, who had undergone successful IVF treatment and were currently pregnant or had given birth within the last two years, participated in semi-structured interviews about their experiences of infertility and PA during pregnancy. Interview transcripts were analysed using interpretative phenomenological analysis. Results Three superordinate themes emerged from the data: ‘navigating away from childlessness and towards motherhood’, ‘negotiating a safe passage’, and ‘balancing the challenges of pregnancy with the needs of the self’. Ten subthemes indicated the processes adopted to navigate experiences of infertility, the IVF process, and subsequent decision-making about PA during pregnancy. Conclusion PA during pregnancy was experienced as a way to soothe the self and control the experience of pregnancy; however, this was mediated by concerns about safety and physical limitations on PA. Limitations of the study are considered, as well as implications for clinical practice and directions for future research

Loss Tolerant Optical Qubits

We present a linear optics quantum computation scheme that employs a new encoding approach that incrementally adds qubits and is tolerant to photon loss errors. The scheme employs a circuit model but uses techniques from cluster state computation and achieves comparable resource usage. To illustrate our techniques we describe a quantum memory which is fault tolerant to photon loss

Observations of Marine Birds and Mammals Wintering at Polynyas and Ice Edges in the Belcher Islands, Nunavut, Canada

In the Belcher Islands, southeast Hudson Bay, Canada, two types of open water exist during winter: 1) large, wind-driven expanses of water along landfast ice edges and 2) recurring polynyas located between small islands (most <10 ha and <15 m deep). In severe winters, only polynyas persist. In March 1998 and 1999, we recorded the species and numbers of birds and marine mammals present at ten polynyas and along four landfast ice edges around the Belcher Islands. To help interpret our observations, we also collected traditional ecological knowledge from local Inuit. Large flocks of common eiders Somateria mollissima (200-12500 birds) were seen along floe edges, and small groups occurred in some polynyas. King eiders S. spectabilis were also observed at several locations, always associated with common eiders. Oldsquaw ducks Clangula hyemalis were common (flocks of 100-500 birds) and occurred primarily at polynyas. Our observations of king eiders represent a significant northern range expansion for this species in Canada during winter. Ravens Corvus corax and snowy owls Nyctea scandiaca were observed along landfast ice edges. Ravens were feeding on the remains of seals killed by Inuit hunters and polar bears Ursus maritimus, and owls apparently hunted sea ducks that were loitering on ice edges at night. We regularly observed bearded seals Erignathus barbatus and ringed seals Phoca hispida at polynyas and floe edges. One beluga whale Delphinapterus leucas was observed by our Inuit guides along a western landfast ice edge, and three walrus Odobenus rosmarus were observed at a floe edge along the southern margin of the Belcher Islands. Clearly, the small recurring polynyas and ice floe edges around the Belcher Islands are important wintering habitat for oldsquaw and common and king eider ducks.L'hiver, dans les îles Belcher, au sud-est de la baie d'Hudson (Canada), l'eau libre est présente sous deux formes: 1) de vastes étendues d'eau créées par le vent, longeant la lisière de la glace de rive et 2), des polynies récurrentes situées entre de petites îles (dont la plupart ont une superficie < 10 ha et une profondeur < 15 m). Durant les hivers très rigoureux, seules persistent les polynies. En mars 1998 et 1999, nous avons relevé les espèces et le nombre d'oiseaux et de mammifères marins présents à dix polynies et le long de quatre lisières de glace de rive autour des îles Belcher. Afin de nous aider à interpréter nos observations, nous avons aussi procédé à la collecte de savoir écologique traditionnel auprès des Inuit de la région. On a observé de grandes volées d'eider à duvet Somateria mollissima (200 à 12 500 oiseaux) le long de floes, et on en a trouvé de petits groupes dans quelques polynies. On a également observé à plusieurs endroits la présence de l'eider à tête grise S. spectabilis, toujours en association avec l'eider à duvet. On a souvent retrouvé le harelde kakawi Clangula hyemalis (en volées de 100 à 500 oiseaux), et ce, surtout dans les polynies. Nos relevés de l'eider à tête grise révèlent, pour cette espèce, une expansion notable de son territoire septentrional au Canada durant l'hiver. On a observé le grand corbeau Corvus corax et le harfang des neiges Nyctea scandiaca sur la lisière de la glace de rive. Les corbeaux se nourrissaient des restes de phoques tués par les chasseurs inuit et les ours polaires Ursus maritimus, et il semble que les harfangs chassaient le canard de mer qui s'aventurait la nuit sur la lisière de glace. On a vu de façon régulière des phoques barbus Erignathus barbatus et des phoques annelés Phoca hispida dans les polynies et au bord des floes. Un bélouga Delphinapterus leucas a été aperçu par nos guides inuit le long d'une lisière occidentale de glace de rive, et trois morses Odobenus rosmarus ont été observés au bord d'un floe longeant la rive méridionale des îles Belcher. Il est évident que les petites polynies récurrentes et les bords des floes de glace autour des îles Belcher représentent un habitat d'hivernage majeur pour le harelde kakawi ainsi que l'eider à duvet et l'eider à tête grise

Evidence of Population Declines among Common Eiders Breeding in the Belcher Islands, Northwest Territories

Information regarding the status of common eiders, Somateria mollissima, breeding in the Canadian Arctic is sorely lacking. In 1997, we surveyed five island archipelagoes in the Belcher Islands in Hudson Bay (56 00 - 57 30 N, 79 30 - 80 00 W) from 3 to 23 July. Our results were compared with eider surveys of the same islands completed between 1985 and 1989 using a standard protocol. We found 1416 eiders on 431 islands. Most (94.1%) were found while the female was still incubating. In all five island groups surveyed, the number of nesting eiders declined significantly (overall decline of 75.0% from 1985-88 to 1997, range: 62.3-84.0%). In 1997, nesting islands and adjacent waters were free of ice, and eiders nested early and laid large clutches (range: 4.0-4.4±1.0-1.2 SD). These conditions indicate a good nesting season, and we inferred that extensive nonbreeding by female eiders in 1997 did not account for the observed decline. A large reported die-off of eiders during the winter of 1991-92, which occurred when areas of open water froze, was the most likely cause of the decline. Our results raise serious conservation concerns, because eider populations are sensitive to reductions in adult survival and this population is harvested throughout the year by subsistence hunters.On a grandement besoin d'information sur le statut de l'eider à duvet Somateria mollissima qui niche dans l'Arctique canadien. En 1997, du 3 au 23 juillet, on a effectué des relevés dans cinq archipels des îles Belcher situées dans la baie d'Hudson (56°00'-57°30' N., 79°30'-80°00' O.) On a comparé nos résultats suivant un protocole normalisé à des relevés d'eiders effectués dans les mêmes îles entre 1985 et 1989. On a trouvé 1416 eiders dans 431 îles. La plupart (94,1 p. cent) ont été relevés alors que la femelle était encore en train de couver. Dans chacun des cinq groupes d'îles étudiés, le nombre d'eiders nicheurs avait enregistré une baisse importante (déclin global de 75,0 p. cent de 1985 à 1989, fourchette de 62,3 à 84,0 p. cent). En 1997, les îles de nidification et les eaux adjacentes étaient libres de glace; les eiders ont niché tôt et la taille des pontes était importante (fourchette: 4,0 à 4,4 ± écart-type de 1,0 à 1,2). Ces conditions sont révélatrices d'une bonne saison de reproduction, et nous en déduisons que la non-reproduction généralisée par les eiders femelles en 1997 n'explique pas le déclin enregistré. C'est très probablement la mortalité massive d'eiders enregistrée au cours de l'hiver de 1991-92, survenue quand les surfaces d'eau libre ont gelé, qui a été responsable du déclin. Nos résultats soulèvent d'importantes questions en matière de conservation, car les populations d'eiders sont sensibles aux baisses de survie adulte et que, tout au long de l'année, cette population fait l'objet de prélèvements dans le cadre de la chasse de subsistance

Population Trends of Gulls and Arctic Terns Nesting in the Belcher Islands, Nunavut

Little information exists on the population trends of gulls and terns nesting in the Arctic. In 1997, we surveyed the number of glaucous gull (Larus hyperboreus), herring gull (Larus argentatus), and arctic tern (Sterna paradisaea) nests on the Belcher Islands (56°00'-57°30'N, 79°30'-80°00'W). We compared our results with the mean number of nests per island counted in the Belcher Islands in the late 1980s using the same survey methods. The mean number of gull nests per island had declined in all five archipelagos surveyed, and the decline was significant in three regions. The number of arctic tern nests had also declined in all three regions where they were originally present, although this decline was significant in only one region. The causes of these apparent declines are unknown. Adult mortality or emigration of gulls from the area may have occurred in response to changes in polynya formation during recent winters, which restricted access to marine food sources. Reproductive success of gulls may also be low in response to the recent 75% decline in common eiders nesting in the Belcher Islands. Eider eggs and ducklings are an important food source for gulls during the breeding season. The decline of nesting arctic terns may reflect either winter mortality of tern populations caused by unknown factors or emigration out of the Belcher Islands in response to regional egging and disturbance by local residents.Il existe peu de renseignements sur les tendances dans les changements de population des mouettes et sternes qui nichent dans l'Arctique. En 1997, on a établi un relevé des nids du goéland bourgmestre (Larus hyperboreus), du goéland argenté (Larus argentatus) et de la sterne arctique (Sterna paradisaea) dans les îles Belcher (56° 00' - 57° 30' de latit. N., 79° 30'- 80° 00' de longit. O.). Nous avons comparé nos résultats avec le nombre moyen de nids par île comptés dans les îles Belcher à la fin des années 1980, en employant les mêmes méthodes de relevés. Le nombre moyen de nids de goélands par île a baissé dans les cinq archipels étudiés, et la baisse s'est révélée importante dans trois régions. Le nombre de nids de sternes arctiques avait également baissé dans les trois régions où elles étaient présentes à l'origine, bien que ce déclin ne fût important que dans une seule région. On ne connaît pas les causes de ces baisses apparentes. La mortalité adulte ou l'émigration des goélands de cette zone aurait pu se produire en réponse aux changements survenus dans la formation de la polynie au cours des derniers hivers - changements qui auraient limité l'accès aux aliments venant de la mer. Le succès de reproduction du goéland pourrait aussi être bas suite au déclin récent de 75 p. cent chez l'eider à duvet qui niche dans les îles Belcher. Les oeufs d'eider et les oisons constituent une importante source alimentaire pour les goélands durant la saison de nidification. Le déclin de la sterne arctique peut être un symptôme soit de la mortalité hivernale des population de sternes dont la cause reste inconnue, soit d'une émigration des îles Belcher en réponse à la collecte des oeufs et à la perturbation dont sont responsables les habitants de la région

Status of Marine Birds of the Southeastern Beaufort Sea

This summary and update of information on the marine birds of the southeastern Beaufort Sea is intended to support discussions on how to improve management of marine resources in the Canadian Beaufort Sea region. Perhaps the most outstanding use of the Beaufort Sea by marine birds is the staging during spring migration by hundreds of thousands of eiders and long-tailed ducks in the early open water off Cape Bathurst and Banks Island. During midsummer, tens of thousands of long-tailed ducks, scoters, scaup, and mergansers moult in the sheltered bays and behind barrier beaches and spits. Although several species of geese, ducks, loons, gulls, and terns nest on islands and in wetlands along the Beaufort Sea coast, this region has relatively few nesting seabirds compared to eastern Arctic Canada and the Bering Sea. Two possible reasons for this are a shortage of cliffs suitable for nesting and a lack of pelagic fish. The five most common sea duck species that occur in the region, long-tailed duck, king eider, common eider, surf scoter, and white-winged scoter, have all declined in numbers since the mid-1970s. Western Arctic brant populations have also declined, although their status within the Beaufort Sea region is unclear. Brant and king eider are the only marine bird species harvested there in substantial numbers. Other threats to Beaufort Sea marine bird populations include oil spills, global warming, coastal development, and contaminants. Certain threats can be managed at a local level since they are a result of local economic development, but others, such as global warming or loss of critical wintering areas, stem from environmental problems outside the region. Solving these issues will require mutual understanding and commitment on the part of numerous countries.Cette récapitulation et mise à jour de l'information sur les oiseaux marins du sud-est de la mer de Beaufort ont été faites dans le but de fournir des arguments sur la façon d'améliorer la gestion des ressources marines dans la zone canadienne de la mer de Beaufort. L'utilisation la plus notable que font les oiseaux marins de la mer de Beaufort est peut-être en tant que halte durant la migration printanière de centaines de milliers d'eiders et de canards à longue queue dans les premières eaux libres au large du cap Bathurst et de l'île Banks. Au milieu de l'été, des dizaines de milliers de canards à longue queue, de macreuses, de fuligules milouinans et de harles muent dans les baies abritées et en arrière des flèches et cordons littoraux. Même si plusieurs espèces d'oies, de canards, de huarts, de mouettes et de sternes nichent sur les îles et dans les zones humides longeant le rivage de la mer de Beaufort, cette région voit relativement peu d'oiseaux marins qui viennent y nicher en comparaison de l'est du Canada arctique et de la mer de Béring. Il y a deux raisons possibles à cet état de choses: trop peu de falaises propices à l'établissement de nids et un manque de poissons pélagiques. Les cinq espèces de canards de mer les plus courantes dans la région, à savoir, le canard à longue queue, l'eider à tête grise, l'eider à duvet, la macreuse à front blanc et la macreuse brune, ont toutes vu leurs nombres décliner depuis le milieu des années 1970. La population de bernaches cravants de l'ouest de l'Arctique est également en déclin, bien que le statut de cet oiseau au sein de la région de la mer de Beaufort ne soit pas évident. La bernache cravant et l'eider à tête grise sont les seules espèces d'oiseaux marins prélevées en nombre important à cet endroit. Parmi les autres facteurs qui menacent les populations d'oiseaux marins de la mer de Beaufort, on compte les déversements d'hydrocarbures, le réchauffement climatique, l'aménagement du littoral et les contaminants. Certaines menaces peuvent être gérées au niveau local vu qu'elles résultent du développement économique local, mais d'autres comme le réchauffement climatique ou la perte d'aires d'hivernage critiques sont issues d'enjeux environnementaux extérieurs à la région. La résolution de ces problèmes passe obligatoirement par une compréhension et un engagement mutuels de la part de nombreux pays

Analytic Solution for the Critical State in Superconducting Elliptic Films

A thin superconductor platelet with elliptic shape in a perpendicular magnetic field is considered. Using a method originally applied to circular disks, we obtain an approximate analytic solution for the two-dimensional critical state of this ellipse. In the limits of the circular disk and the long strip this solution is exact, i.e. the current density is constant in the region penetrated by flux. For ellipses with arbitrary axis ratio the obtained current density is constant to typically 0.001, and the magnetic moment deviates by less than 0.001 from the exact value. This analytic solution is thus very accurate. In increasing applied magnetic field, the penetrating flux fronts are approximately concentric ellipses whose axis ratio b/a < 1 decreases and shrinks to zero when the flux front reaches the center, the long axis staying finite in the fully penetrated state. Analytic expressions for these axes, the sheet current, the magnetic moment, and the perpendicular magnetic field are presented and discussed. This solution applies also to superconductors with anisotropic critical current if the anisotropy has a particular, rather realistic form.Comment: Revtex file and 13 postscript figures, gives 10 pages of text with figures built i

Increasing compliance with low tidal volume ventilation in the ICU with two nudge-based interventions: evaluation through intervention time-series analyses

Objectives: Low tidal volume (TVe) ventilation improves outcomes for ventilated patients, and the majority of clinicians state they implement it. Unfortunately, most patients never receive low TVes. ‘Nudges’ influence decision-making with subtle cognitive mechanisms and are effective in many contexts. There have been few studies examining their impact on clinical decision-making. We investigated the impact of 2 interventions designed using principles from behavioural science on the deployment of low TVe ventilation in the intensive care unit (ICU). Setting: University Hospitals Bristol, a tertiary, mixed medical and surgical ICU with 20 beds, admitting over 1300 patients per year. Participants: Data were collected from 2144 consecutive patients receiving controlled mechanical ventilation for more than 1 hour between October 2010 and September 2014. Patients on controlled mechanical ventilation for more than 20 hours were included in the final analysis. Interventions: (1) Default ventilator settings were adjusted to comply with low TVe targets from the initiation of ventilation unless actively changed by a clinician. (2) A large dashboard was deployed displaying TVes in the format mL/kg ideal body weight (IBW) with alerts when TVes were excessive. Primary outcome measure: TVe in mL/kg IBW. Findings: TVe was significantly lower in the defaults group. In the dashboard intervention, TVe fell more quickly and by a greater amount after a TVe of 8 mL/kg IBW was breached when compared with controls. This effect improved in each subsequent year for 3 years. Conclusions: This study has demonstrated that adjustment of default ventilator settings and a dashboard with alerts for excessive TVe can significantly influence clinical decision-making. This offers a promising strategy to improve compliance with low TVe ventilation, and suggests that using insights from behavioural science has potential to improve the translation of evidence into practice