228 research outputs found
The role of financial variables in predicting economic activity
Previous research has shown that the US business cycle leads the European cycle by a few quarters, and can therefore help predicting euro area GDP. We investigate whether financial variables provide additional predictive power. We use a VAR model of the US and the euro area GDPs and extend it to take into account common global shocks and information provided by selected combinations of financial variables. In-sample analysis shows that shocks to financial variables influence real activity with a peak around 4 to 6 quarters after the shock. Out-of-sample Root-Mean- Squared Forecast Error (RMFE) shows that adding financial variables yields smaller errors in fore-casting US economic activity, especially at a five- quarter horizon, but the gain is overall tiny in economic terms. This link is even less prominent in the euro area, where financial indicators do not improve short and medium term GDP forecasts even when their timely availability, relative to a given GDP release, is exploited. The same conclusion is reached with a dataset of quarterly industrial production indices, although financial variables marginally improve fore- casts of monthly industrial production. We argue that the findings that financial variables have no predictive power for future activity in the euro area relate to the unconditional nature of the RMFE metric. When forecasting ability is assessed as if in real time (i.e. conditionally on the information available at the time when forecasts are made), we find that models using financial variables would have been preferred in many episodes, and in particular between 1999 and 2002. Results from the historical decomposition of a VAR model indeed suggest that in that period shocks were predominantly of financial nature. JEL Classification: F30, F42, F47conditional forecast, Financial Variables, international linkages, VAR
Consistent measures of systemic risk
This paper presents a methodology to infer multivariate densities that characterize the asset values for a system of financial institutions, and applies it to quantify systemic risk. These densities, which are inferred from partial information but are consistent with the observed probabilities of distress of financial institutions, outperform parametric distributions typically employed in risk measurement. The multivariate density approach allows us to propose complementary and statistically consistent metrics of systemic risk, which we estimate using market-based data to analyze the evolution of systemic risk in Europe and the U.S., throughout the financial crisis
Macroprudential stress tests: a reduced-form approach to quantifying systemic risk losses
We present a novel approach that incorporates individual entity stress testing and losses from systemic risk effects (SE losses) into macroprudential stress testing. SE losses are measured using a reduced-form model to value financial entity assets, conditional on macroeconomic stress and the distress of other entities in the system. This valuation is made possible by a multivariate density which characterizes the asset values of the financial entities making up the system. In this paper this density is estimated using CIMDO, a statistical approach, which infers densities that are consistent with entities' probabilities of default, which in this case are estimated using market-based data. Hence, SE losses capture the effects of interconnectedness structures that are consistent with markets' perceptions of risk. We then show how SE losses can be decomposed into the likelihood of distress and the magnitude of losses, thereby quantifying the contribution of specific entities to systemic contagion. To illustrate the approach, we quantify SE losses due to Lehman Brothers' default
Estudio y diseño para el reacondicionamiento de áreas hospitalarias de Lima para cumplir los estándares de calidad ambiental de ruido utilizando un software de modelamiento acústico
El presente trabajo de investigación tuvo como objetivo principal el estudio de los niveles de ruido dentro de los hospitales, específicamente en las áreas de recuperación del Hospital del Niño, así como una propuesta para la reducción de los niveles de ruido. La medición de los niveles de ruido se efectuó en los corredores aledaños a los ambientes de recuperación, estas mediciones se realizaron con un sonómetro calibrado adecuadamente. De esta forma fue posible la determinación de los niveles de ruido máximo y su distribución en el horario diurno. La determinación de los niveles de ruido dentro de los ambientes de recuperación no fue posible, pues estos se encontraban en uso, durante el desarrollo del trabajo de investigación; sin embargo, se determinó la distribución espacial de los niveles de ruido mediante el modelamiento de la presión sonora, usando el software SoundPLAN. Finalmente, se propuso la colocación de paneles de corcho de e=20 mm, como una técnica que permita la reducción de los niveles de ruido dentro los ambientes de recuperación. Los resultados de las mediciones mostraron que los niveles de ruido pueden alcanzar los 79.4 dBA, en los corredores aledaños a las áreas de recuperación, mientras que los niveles de ruido alcanzaron los 55 dBA, dentro de los mismos, además, el uso de paneles de corcho permitió la reducción del ruido hasta en un 21%.El presente trabajo de investigación tuvo como objetivo principal el estudio de los niveles de ruido dentro de los hospitales, específicamente en las áreas de recuperación del Hospital del Niño, así como una propuesta para la reducción de los niveles de ruido. La medición de los niveles de ruido se efectuó en los corredores aledaños a los ambientes de recuperación, estas mediciones se realizaron con un sonómetro calibrado adecuadamente. De esta forma fue posible la determinación de los niveles de ruido máximo y su distribución en el horario diurno. La determinación de los niveles de ruido dentro de los ambientes de recuperación no fue posible, pues estos se encontraban en uso, durante el desarrollo del trabajo de investigación; sin embargo, se determinó la distribución espacial de los niveles de ruido mediante el modelamiento de la presión sonora, usando el software SoundPLAN. Finalmente, se propuso la colocación de paneles de corcho de e=20 mm, como una técnica que permita la reducción de los niveles de ruido dentro los ambientes de recuperación. Los resultados de las mediciones mostraron que los niveles de ruido pueden alcanzar los 79.4 dBA, en los corredores aledaños a las áreas de recuperación, mientras que los niveles de ruido alcanzaron los 55 dBA, dentro de los mismos, además, el uso de paneles de corcho permitió la reducción del ruido hasta en un 21%.Tesi
The R136 star cluster hosts several stars whose individual masses greatly exceed the accepted 150 Msun stellar mass limit
Spectroscopic analyses of H-rich WN5-6 stars within the young star clusters
NGC 3603 and R136 are presented, using archival HST & VLT spectroscopy, & high
spatial resolution near-IR photometry. We derive high T* for the WN stars in
NGC 3603 (T*~42+/-2 kK) & R136 (T*~53+/-3 kK) plus clumping-corrected dM/dt ~
2-5x10^-5 Msun/yr which closely agree with theoretical predictions. These stars
make a disproportionate contribution to the global budget of their host
clusters. R136a1 alone supplies ~7% of N(LyC) of the entire 30 Dor region.
Comparisons with stellar models calculated for the main-sequence evolution of
85-500 Msun suggest ages of ~1.5 Myr & M_init in the range 105 - 170 Msun for 3
systems in NGC 3603, plus 165-320 Msun for 4 stars in R136. Our high stellar
masses are supported by dynamical mass determinations for the components of NGC
3603 A1. We consider the predicted L_X of the R136 stars if they were close,
colliding wind binaries. R136c is consistent with a colliding wind binary
system. However, short period, colliding wind systems are excluded for R136a WN
stars if mass ratios are of order unity. Widely separated systems would have
been expected to harden owing to early dynamical encounters with other massive
stars in such a dense environment. From simulated star clusters, whose
constituents are randomly sampled from the Kroupa IMF, both clusters are
consistent with a tentative upper mass limit of ~300 Msun. The Arches cluster
is either too old, exhibits a deficiency of very massive stars, or more likely
stellar masses have been underestimated - M_init for the most luminous stars in
the Arches cluster approach 200 Msun according to contemporary stellar &
photometric results. The potential for stars greatly exceeding 150 Msun within
metal-poor galaxies suggests that such pair-instability SNe could occur within
the local universe, as has been claimed for SN 2007bi (abridged).Comment: 20 pages, 14 figures, accepted for MNRAS. Version with higher
resolution figures is available from
http://pacrowther.staff.shef.ac.uk/R136.pdf See also
http://www.eso.org/public/news/eso1030/ from Wed 21 from noon (CEST
Electrohydrodynamic model of vesicle deformation in alternating electric fields
We develop an analytical theory to explain the experimentally-observed
morphological transitions of giant vesicles induced by AC electric fields (1).
The model treats the inner and suspending media as lossy dielectrics, while the
membrane as an ion-impermeable flexible incompressible-fluid sheet. The vesicle
shape is obtained by balancing electric, hydrodynamic, and bending stresses
exerted on the membrane. Considering a nearly spherical vesicle, the solution
to the electrohydrodynamic problem is obtained as a regular perturbation
expansion in the excess area.
The theory predicts that stationary vesicle deformation depends on field
frequency and conductivity conditions. If the inner fluid is more conducting
than the suspending medium, the vesicle always adopts a prolate shape. In the
opposite case, the vesicle undergoes a transition from a prolate to oblate
ellipsoid at a critical frequency, which the theory identifies with the inverse
membrane charging time. At frequencies higher than the inverse Maxwell-Wagner
polarization time, the electrohydrodynamic stresses become too small to alter
the vesicle's quasi-spherical rest shape. The analysis shows that the evolution
towards the stationary vesicle deformation strongly depends on membrane
properties such as viscosity. The model can be applied to rationalize the
transient and steady deformation of biological cells in electric fields
The state of the Martian climate
60°N was +2.0°C, relative to the 1981–2010 average value (Fig. 5.1). This marks a new high for the record. The average annual surface air temperature (SAT) anomaly for 2016 for land stations north of starting in 1900, and is a significant increase over the previous highest value of +1.2°C, which was observed in 2007, 2011, and 2015. Average global annual temperatures also showed record values in 2015 and 2016. Currently, the Arctic is warming at more than twice the rate of lower latitudes
Atrasentan and renal events in patients with type 2 diabetes and chronic kidney disease (SONAR): a double-blind, randomised, placebo-controlled trial
Background: Short-term treatment for people with type 2 diabetes using a low dose of the selective endothelin A receptor antagonist atrasentan reduces albuminuria without causing significant sodium retention. We report the long-term effects of treatment with atrasentan on major renal outcomes. Methods: We did this double-blind, randomised, placebo-controlled trial at 689 sites in 41 countries. We enrolled adults aged 18–85 years with type 2 diabetes, estimated glomerular filtration rate (eGFR)25–75 mL/min per 1·73 m 2 of body surface area, and a urine albumin-to-creatinine ratio (UACR)of 300–5000 mg/g who had received maximum labelled or tolerated renin–angiotensin system inhibition for at least 4 weeks. Participants were given atrasentan 0·75 mg orally daily during an enrichment period before random group assignment. Those with a UACR decrease of at least 30% with no substantial fluid retention during the enrichment period (responders)were included in the double-blind treatment period. Responders were randomly assigned to receive either atrasentan 0·75 mg orally daily or placebo. All patients and investigators were masked to treatment assignment. The primary endpoint was a composite of doubling of serum creatinine (sustained for ≥30 days)or end-stage kidney disease (eGFR <15 mL/min per 1·73 m 2 sustained for ≥90 days, chronic dialysis for ≥90 days, kidney transplantation, or death from kidney failure)in the intention-to-treat population of all responders. Safety was assessed in all patients who received at least one dose of their assigned study treatment. The study is registered with ClinicalTrials.gov, number NCT01858532. Findings: Between May 17, 2013, and July 13, 2017, 11 087 patients were screened; 5117 entered the enrichment period, and 4711 completed the enrichment period. Of these, 2648 patients were responders and were randomly assigned to the atrasentan group (n=1325)or placebo group (n=1323). Median follow-up was 2·2 years (IQR 1·4–2·9). 79 (6·0%)of 1325 patients in the atrasentan group and 105 (7·9%)of 1323 in the placebo group had a primary composite renal endpoint event (hazard ratio [HR]0·65 [95% CI 0·49–0·88]; p=0·0047). Fluid retention and anaemia adverse events, which have been previously attributed to endothelin receptor antagonists, were more frequent in the atrasentan group than in the placebo group. Hospital admission for heart failure occurred in 47 (3·5%)of 1325 patients in the atrasentan group and 34 (2·6%)of 1323 patients in the placebo group (HR 1·33 [95% CI 0·85–2·07]; p=0·208). 58 (4·4%)patients in the atrasentan group and 52 (3·9%)in the placebo group died (HR 1·09 [95% CI 0·75–1·59]; p=0·65). Interpretation: Atrasentan reduced the risk of renal events in patients with diabetes and chronic kidney disease who were selected to optimise efficacy and safety. These data support a potential role for selective endothelin receptor antagonists in protecting renal function in patients with type 2 diabetes at high risk of developing end-stage kidney disease. Funding: AbbVie
Production of He-4 and (4) in Pb-Pb collisions at root(NN)-N-S=2.76 TeV at the LHC
Results on the production of He-4 and (4) nuclei in Pb-Pb collisions at root(NN)-N-S = 2.76 TeV in the rapidity range vertical bar y vertical bar <1, using the ALICE detector, are presented in this paper. The rapidity densities corresponding to 0-10% central events are found to be dN/dy4(He) = (0.8 +/- 0.4 (stat) +/- 0.3 (syst)) x 10(-6) and dN/dy4 = (1.1 +/- 0.4 (stat) +/- 0.2 (syst)) x 10(-6), respectively. This is in agreement with the statistical thermal model expectation assuming the same chemical freeze-out temperature (T-chem = 156 MeV) as for light hadrons. The measured ratio of (4)/He-4 is 1.4 +/- 0.8 (stat) +/- 0.5 (syst). (C) 2018 Published by Elsevier B.V.Peer reviewe
The Severe Typhoid Fever in Africa Program: Study Design and Methodology to Assess Disease Severity, Host Immunity, and Carriage Associated With Invasive Salmonellosis
Background. Invasive salmonellosis is a common community-acquired bacteremia in persons residing in sub-Saharan Africa. However, there is a paucity of data on severe typhoid fever and its associated acute and chronic host immune response and carriage. The Severe Typhoid Fever in Africa (SETA) program, a multicountry surveillance study, aimed to address these research gaps and contribute to the control and prevention of invasive salmonellosis. Methods. A prospective healthcare facility-based surveillance with active screening of enteric fever and clinically suspected severe typhoid fever with complications was performed using a standardized protocol across the study sites in Burkina Faso, the Democratic Republic of Congo (DRC), Ethiopia, Ghana, Madagascar, and Nigeria. Defined inclusion criteria were used for screening of eligible patients for enrollment into the study. Enrolled patients with confirmed invasive salmonellosis by blood culture or patients with clinically suspected severe typhoid fever with perforation were eligible for clinical follow-up. Asymptomatic neighborhood controls and immediate household contacts of each case were enrolled as a comparison group to assess the level of Salmonella-specific antibodies and shedding patterns. Healthcare utilization surveys were performed to permit adjustment of incidence estimations. Postmortem questionnaires were conducted in medically underserved areas to assess death attributed to invasive Salmonella infections in selected sites. Results. Research data generated through SETA aimed to address scientific knowledge gaps concerning the severe typhoid fever and mortality, long-term host immune responses, and bacterial shedding and carriage associated with natural infection by invasive salmonellae. Conclusions. SETA supports public health policy on typhoid immunization strategy in Africa
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