Lessons Learned from Characterization, Performance Assessment, and EPA Regulatory Review of the 1996 Actinide Source Term for the Waste Isolation Pilot Plant

The Waste Isolation Pilot Plant (WIPP) is a US Department of Energy (DOE) facility for the permanent disposal of transuranic waste from defense activities. In 1996, the DOE submitted the Title 40 CFR Part 191 Compliance Certification Application for the Waste Isolation Pilot Plant (CCA) to the US Environmental Protection Agency (EPA). The CCA included a probabilistic performance assessment (PA) conducted by Sandia National Laboratories to establish compliance with the quantitative release limits defined in 40 CFR 191.13. An experimental program to collect data relevant to the actinide source term began around 1989, which eventually supported the 1996 CCA PA actinide source term model. The actinide source term provided an estimate of mobile dissolved and colloidal Pu, Am, U, Th, and Np concentrations in their stable oxidation states, and accounted for effects of uncertainty in the chemistry of brines in waste disposal areas. The experimental program and the actinide source term included in the CCA PA underwent EPA review lasting more than 1 year. Experiments were initially conducted to develop data relevant to the wide range of potential future conditions in waste disposal areas. Interim, preliminary performance assessments and actinide source term models provided insight allowing refinement of experiments and models. Expert peer review provided additional feedback and confidence in the evolving experimental program. By 1995, the chemical database and PA predictions of WIPP performance were considered reliable enough to support the decision to add an MgO backfill to waste rooms to control chemical conditions and reduce uncertainty in actinide concentrations, especially for Pu and Am. Important lessons learned through the characterization, PA modeling, and regulatory review of the actinide source term are (1) experimental characterization and PA should evolve together, with neither activity completely dominating the other, (2) the understanding of physical processes required to develop conceptual models is greater than can be represented in PA models, (3) experimentalists should be directly involved in model and parameter abstraction and simplification for PA, and (4) external expert review should be incorporated early in a project to increase confidence long before regulatory reviews begin

Readmissions Within 48 Hours of Discharge: Reasons, Risk Factors, and Potential Improvements.

Hospital readmission rate is an important quality metric and has been recognized as a key measure of hospital value-based purchasing programs. This study aimed to assess the risk factors for hospital readmission with a focus on potentially preventable early readmissions within 48 hours of discharge. This is a retrospective cohort study. This study was conducted at a tertiary academic facility with a standardized enhanced recovery pathway. Consecutive patients undergoing elective major colorectal resections between 2011 and 2016 were included. Univariable and multivariable risk factors for overall and early (<48 hours) readmissions were identified. Specific surgical and medical reasons for readmission were compared between early and late readmissions. In total, 526 of 4204 patients (12.5%) were readmitted within 30 days of discharge. Independent risk factors were ASA score (≥3; OR, 1.5; 95% CI, 1.1-2), excess perioperative weight gain (OR, 1.7; 95% CI, 1.3-2.3), ileostomy (OR, 1.4; 95% CI, 1-2), and transfusion (OR, 2; 95% CI, 1.4-3), or reoperation (OR, 11.4; 95% CI, 7.4-17.5) during the index stay. No potentially preventable risk factor for early readmission (128 patients, 24.3% of all readmissions, 3% of total cohort) was identified, and index hospital stay of ≤3 days was not associated with increased readmission (OR, 0.9; 95% CI, 0.7-1.2). Although ileus and small-bowel obstruction (early: 43.8% vs late: 15.5%, p < 0.001) were leading causes for early readmissions, deep infections (3.9% vs 16.3%, p < 0.001) and acute kidney injury (0% vs 5%, p = 0.006) were mainly observed during readmissions after 48 hours. Risk of underreporting due to loss of follow-up and the potential co-occurrence of complications were limitations of this study. Early hospital readmission was mainly due to ileus or bowel obstruction, whereas late readmissions were related to deep infections and acute kidney injury. A suspicious attitude toward potential ileus-related symptoms before discharge and dedicated education for ostomy patients are important. A short index hospital stay was not associated with increased readmission rates. See Video Abstract at http://links.lww.com/DCR/B237. REINGRESOS DENTRO DE LAS 48 HORAS POSTERIORES AL ALTA: RAZONES, FACTORES DE RIESGO Y POSIBLES MEJORAS: La tasa de reingreso hospitalario es una métrica de calidad importante y ha sido reconocida como una medida clave de los programas hospitalarios de compras basadas en el valor.Evaluar los factores de riesgo para el reingreso hospitalario con énfasis en reingresos tempranos potencialmente prevenibles dentro de las 48 horas posteriores al alta.Estudio de cohorte retrospectivo.Institución académica terciaria con programa de recuperación mejorada estandarizado.Pacientes consecutivos sometidos a resecciones colorrectales mayores electivas entre 2011 y 2016.Se identificaron factores de riesgo uni y multivariables para reingresos totales y tempranos (<48 horas). Se compararon razones médicas y quirúrgicas específicas para el reingreso entre reingresos tempranos y tardíos.En total, 526/4204 pacientes (12,5%) fueron readmitidos dentro de los 30 días posteriores al alta. Los factores de riesgo independientes fueron puntuación ASA (≥3, OR 1.5; IC 95% 1.1-2), aumento de peso perioperatorio excesivo (OR 1.7; IC 95% 1.3-2.3), ileostomía (OR 1.4, IC 95%: 1-2) y transfusión (OR 2, IC 95% 1.4-3) o reoperación (OR 11.4; IC 95% 7.4-17.5) durante la estadía índice. No se identificó ningún factor de riesgo potencialmente prevenible para el reingreso temprano (128 pacientes, 24.3% de todos los reingresos, 3% de la cohorte total), y la estadía hospitalaria índice de ≤ 3 días no se asoció con un aumento en el reingreso (OR 0.9; IC 95% 0.7-1.2) Mientras que el íleo / obstrucción del intestino delgado (temprano: 43.8% vs. tardío: 15.5%, p < 0.001) fueron las principales causas de reingresos tempranos, infecciones profundas (3.9% vs 16.3%, p < 0.001) y lesión renal aguda (0 vs 5%, p = 0.006) se observaron principalmente durante los reingresos después de 48 horas.Riesgo de subregistro debido a la pérdida en el seguimiento, posible co-ocurrencia de complicaciones.El reingreso hospitalario temprano se debió principalmente a íleo u obstrucción intestinal, mientras que los reingresos tardíos se relacionaron con infecciones profundas y lesión renal aguda. Es importante tener una actitud suspicaz hacia los posibles síntomas relacionados con el íleo antes del alta y una educación específica para los pacientes con ostomía. La estadía hospitalaria índice corta no se asoció con mayores tasas de reingreso. Consulte Video Resumen en http://links.lww.com/DCR/B237

The starburst phenomenon from the optical/near-IR perspective

The optical/near-IR stellar continuum carries unique information about the stellar population in a galaxy, its mass function and star-formation history. Star-forming regions display rich emission-line spectra from which we can derive the dust and gas distribution, map velocity fields, metallicities and young massive stars and locate shocks and stellar winds. All this information is very useful in the dissection of the starburst phenomenon. We discuss a few of the advantages and limitations of observations in the optical/near-IR region and focus on some results. Special attention is given to the role of interactions and mergers and observations of the relatively dust-free starburst dwarfs. In the future we expect new and refined diagnostic tools to provide us with more detailed information about the IMF, strength and duration of the burst and its triggering mechanisms.Comment: 6 pages, 3 figures, to appear in "Starbursts: from 30 Doradus to Lyman Break Galaxies" 2005, eds. R. de Grijs and R. M. Gonzalez Delgado (Kluwer

Constraining the Detailed Balance Condition in Horava Gravity with Cosmic Accelerating Expansion

In 2009 Ho\v{r}ava proposed a power-counting renormalizable quantum gravity theory. Afterwards a term in the action that softly violates the detailed balance condition has been considered with the attempt of obtaining a more realistic theory in its IR-limit. This term is proportional to $\omega R^{(3)}$, where $\omega$ is a constant parameter and $R^{(3)}$ is the spatial Ricci scalar. In this paper we derive constraints on this IR-modified Ho\v{r}ava theory using the late-time cosmic accelerating expansion observations. We obtain a lower bound of $|\omega|$ that is nontrivial and depends on $\Lambda_W$, the cosmological constant of the three dimensional spatial action in the Ho\v{r}ava gravity. We find that to preserve the detailed balance condition, one needs to fine-tune $\Lambda_W$ such that - 2.29\times 10^{-4}< (c^2 \Lambda_W)/(H^2_0 \currentDE) - 2 < 0 , where $H_0$ and \currentDE are the Hubble parameter and dark energy density fraction in the present epoch, respectively. On the other hand, if we do not insist on the detailed balance condition, then the valid region for $\Lambda_W$ is much relaxed to -0.39< (c^2 \Lambda_W)/(H^2_0 \currentDE) - 2 < 0.12. We find that although the detailed balance condition cannot be ruled out, it is strongly disfavored.Comment: 22 pages with 7 figures, references adde

Interacting Ghost Dark Energy in Non-Flat Universe

A new dark energy model called "ghost dark energy" was recently suggested to explain the observed accelerating expansion of the universe. This model originates from the Veneziano ghost of QCD. The dark energy density is proportional to Hubble parameter, $\rho_D=\alpha H$, where $\alpha$ is a constant of order $\Lambda_{\rm QCD}^3$ and $\Lambda_{\rm QCD}\sim 100 MeV$ is QCD mass scale. In this paper, we extend the ghost dark energy model to the universe with spatial curvature in the presence of interaction between dark matter and dark energy. We study cosmological implications of this model in detail. In the absence of interaction the equation of state parameter of ghost dark energy is always $w_D > -1$ and mimics a cosmological constant in the late time, while it is possible to have $w_D < -1$ provided the interaction is taken into account. When $k = 0$, all previous results of ghost dark energy in flat universe are recovered. To check the observational consistency, we use Supernova type Ia (SNIa) Gold sample, shift parameter of Cosmic Microwave Background radiation (CMB) and the Baryonic Acoustic Oscillation peak from Sloan Digital Sky Survey (SDSS). The best fit values of free parameter at $1\sigma$ confidence interval are: $\Omega_m^0= 0.35^{+0.02}_{-0.03}$, $\Omega_D^0=0.75_{-0.04}^{+0.01}$ and $b^2=0.08^{+0.03}_{-0.03}$. Consequently the total energy density of universe at present time in this model at 68% level equates to $\Omega_{\rm tot}^0=1.10^{+0.02}_{-0.05}$.Comment: 19 pages, 9 figures. V2: Added comments, observational consequences, references, figures and major corrections. Accepted for publication in General Relativity and Gravitatio

A Single Visualization Technique for Displaying Multiple Metabolite-Phenotype Associations

To assist with management and interpretation of human metabolomics data, which are rapidly increasing in quantity and complexity, we need better visualization tools. Using a dataset of several hundred metabolite measures profiled in a cohort of similar to 1500 individuals sampled from a population-based community study, we performed association analyses with eight demographic and clinical traits and outcomes. We compared frequently used existing graphical approaches with a novel ` rain plot' approach to display the results of these analyses. The ` rain plot' combines features of a raindrop plot and a conventional heatmap to convey results of multiple association analyses. A rain plot can simultaneously indicate e ff ect size, directionality, and statistical significance of associations between metabolites and several traits. This approach enables visual comparison features of all metabolites examined with a given trait. The rain plot extends prior approaches and o ff ers complementary information for data interpretation. Additional work is needed in data visualizations for metabolomics to assist investigators in the process of understanding and convey large-scale analysis results e ff ectively, feasibly, and practically

The Similarity Hypothesis in General Relativity

Self-similar models are important in general relativity and other fundamental theories. In this paper we shall discuss the ``similarity hypothesis'', which asserts that under a variety of physical circumstances solutions of these theories will naturally evolve to a self-similar form. We will find there is good evidence for this in the context of both spatially homogenous and inhomogeneous cosmological models, although in some cases the self-similar model is only an intermediate attractor. There are also a wide variety of situations, including critical pheneomena, in which spherically symmetric models tend towards self-similarity. However, this does not happen in all cases and it is it is important to understand the prerequisites for the conjecture.Comment: to be submitted to Gen. Rel. Gra

Interstellar MHD Turbulence and Star Formation

This chapter reviews the nature of turbulence in the Galactic interstellar medium (ISM) and its connections to the star formation (SF) process. The ISM is turbulent, magnetized, self-gravitating, and is subject to heating and cooling processes that control its thermodynamic behavior. The turbulence in the warm and hot ionized components of the ISM appears to be trans- or subsonic, and thus to behave nearly incompressibly. However, the neutral warm and cold components are highly compressible, as a consequence of both thermal instability in the atomic gas and of moderately-to-strongly supersonic motions in the roughly isothermal cold atomic and molecular components. Within this context, we discuss: i) the production and statistical distribution of turbulent density fluctuations in both isothermal and polytropic media; ii) the nature of the clumps produced by thermal instability, noting that, contrary to classical ideas, they in general accrete mass from their environment; iii) the density-magnetic field correlation (or lack thereof) in turbulent density fluctuations, as a consequence of the superposition of the different wave modes in the turbulent flow; iv) the evolution of the mass-to-magnetic flux ratio (MFR) in density fluctuations as they are built up by dynamic compressions; v) the formation of cold, dense clouds aided by thermal instability; vi) the expectation that star-forming molecular clouds are likely to be undergoing global gravitational contraction, rather than being near equilibrium, and vii) the regulation of the star formation rate (SFR) in such gravitationally contracting clouds by stellar feedback which, rather than keeping the clouds from collapsing, evaporates and diperses them while they collapse.Comment: 43 pages. Invited chapter for the book "Magnetic Fields in Diffuse Media", edited by Elisabete de Gouveia dal Pino and Alex Lazarian. Revised as per referee's recommendation

Recent Developments in Helioseismic Analysis Methods and Solar Data Assimilation

MR and AS have received funding from the European Research Council under the European Union’s Seventh Framework Program (FP/2007-2013)/ERC Grant Agreement no. 307117