Primordial Black Holes from the QCD Axion.

We propose a mechanism to generate primordial black holes (PBHs) that is independent of cosmological inflation and occurs slightly below the QCD phase transition. Our setup relies on the collapse of long-lived string-domain wall networks and is naturally realized in QCD axion models with domain wall number N_{DW}>1 and Peccei-Quinn symmetry broken after inflation. In our framework, dark matter is mostly composed of axions in the meV mass range along with a small fraction, Ω_{PBH}≳10^{-6}Ω_{CDM} of heavy M∼10^{4}-10^{7} M_{⊙} PBHs. The latter could play a role in alleviating some of the shortcomings of the standard cosmological model on subgalactic scales. The scenario might have distinct signatures in ongoing axion searches as well as gravitational wave observatories.

Search for GeV γ-Ray Pair Halos Around Low Redshift Blazars.

We report on the results of a search for γ-ray pair halos with a stacking analysis of low redshift blazars using data from the Fermi Large Area Telescope. For this analysis we used a number of a priori selection criteria, including the spatial and spectral properties of the Fermi sources. The angular distribution of ~1 GeV photons around 24 stacked isolated high-synchrotron-peaked BL Lacs with redshift z<0.5 shows an excess over that of pointlike sources. A frequentist test yields a p value of p~0.01 for the extended emission against the point-source hypothesis. A Bayesian estimation provides Bayes factors log_{10}B_{10}>2, consistent with expectations for pair halos produced in the intergalactic magnetic fields with strength B_{IGMF}~10^{-17}-10^{-15} G.

Detecting chameleon dark energy via an electrostatic analogy.

The late-time accelerated expansion of the Universe could be caused by a scalar field that is screened on small scales, as in the case of chameleon or symmetron scenarios. We present an analogy between such scalar fields and electrostatics, which allows calculation of the field profile for general extended bodies. Interestingly, the field demonstrates a "lightning rod" effect, where it becomes enhanced near the ends of a pointed or elongated object. Drawing from this correspondence, we show that nonspherical test bodies immersed in a background field will experience a net torque caused by the scalar field. This effect, with no counterpart in the gravitational case, can be potentially tested in future experiments.

Differences in radiological patterns, tumour characteristics and diagnostic precision between digital mammography and screen-film mammography in four breast cancer screening programmes in Spain.

OBJECTIVES: To compare tumour characteristics between cancers detected with screen-film mammography (SFM) and digital mammography (DM) and to evaluate changes in positive predictive values (PPVs) for further assessments, for invasive procedures and for distinct radiological patterns in recalled women. METHODS: 242,838 screening mammograms (171,191 SFM and 71,647 DM) from 103,613 women aged 45-69 years, performed in four population-based breast cancer screening programmes in Spain, were included. The tumour characteristics and PPVs of each group were compared. Radiological patterns (masses, calcifications, distortions and asymmetries) among recalled women were described and PPVs were evaluated. RESULTS: The percentages of ductal carcinoma in situ (DCIS) were higher in DM than in SFM both in the first [18.5% vs. 15.8%(p = 0.580)] and in successive screenings [23.2% vs. 15.7%(p = 0.115)]. PPVs for masses, asymmetries and calcifications were higher in DM, being statistically significant in masses (5.3% vs. 3.9%; proportion ratio: 1.37 95%CI: 1.08-1.72). Among cancers detected by calcifications, the percentage of DCIS was higher in DM (60.3% vs. 46.4%, p = 0.060). CONCLUSIONS: PPVs were higher when DM was used, both for further assessments and for invasive procedures, with similar cancer detection rates and no statistically significant differences in tumour characteristics. The greatest improvements in PPVs were found for masses.

Helical magnetic fields from sphaleron decay and baryogenesis.

Many models of baryogenesis rely on anomalous particle physics processes to give baryon number violation. By numerically evolving the electroweak equations on a lattice, we show that baryogenesis in these models creates helical cosmic magnetic fields, though the helicity created is smaller than earlier analytical estimates. After a transitory period, electroweak dynamics is found to conserve the Chern-Simons number and the total electromagnetic helicity. We argue that baryogenesis could lead to magnetic fields of nano-Gauss strength today on astrophysical length scales. In addition to being astrophysically relevant, such helical magnetic fields can provide an independent probe of baryogenesis and CP violation in particle physics.

Association between radiologists' experience and accuracy in interpreting screening mammograms.

BACKGROUND: Radiologists have been observed to differ, sometimes substantially, both in their interpretations of mammograms and in their recommendations for follow-up. The aim of this study was to determine how factors related to radiologists' experience affect the accuracy of mammogram readings. METHODS: We selected a random sample of screening mammograms from a population-based breast cancer screening program. The sample was composed of 30 women with histopathologically-confirmed breast cancer and 170 women without breast cancer after a 2-year follow-up (the proportion of cancers was oversampled). These 200 mammograms were read by 21 radiologists routinely interpreting mammograms, with different amount of experience, and by seven readers who did not routinely interpret mammograms. All readers were blinded to the results of the screening. A positive assessment was considered when a BI-RADS III, 0, IV, V was reported (additional evaluation required). Diagnostic accuracy was calculated through sensitivity and specificity. RESULTS: Average specificity was higher in radiologists routinely interpreting mammograms with regard to radiologists who did not (66% vs 56%; p < .001). Multivariate analysis based on routine readers alone showed that specificity was higher among radiologists who followed-up cases for which they recommended further workup (feedback) (OR 1.37; 95% CI 1.03 to 1.85), those spending less than 25% of the working day on breast radiology (OR 1.49; 95% CI 1.18 to 1.89), and those aged more than 45 years old (OR 1.33; 95% CI 1.12 to 1.59); the variable of average annual volume of mammograms interpreted by radiologists, classified as more or less than 5,000 mammograms per year, was not statistically significant (OR 1.06; 95% CI 0.90 to 1.25). CONCLUSION: Among radiologists who read routinely, volume is not associated with better performance when interpreting screening mammograms, although specificity decreased in radiologists not routinely reading mammograms. Follow-up of cases for which further workup is recommended might reduce variability in mammogram readings and improve the quality of breast cancer screening programs.

511 keV photons from superconducting cosmic strings.

We show that a tangle of light superconducting strings in the Milky Way could be the source of the observed 511 keV emission from electron-positron annihilation in the Galactic bulge. The scenario predicts a flux that is in agreement with observations if the strings are at the approximately 1 TeV scale, making the particle physics within reach of planned accelerator experiments. The emission is directly proportional to the galactic magnetic field, and future observations should be able to differentiate the superconducting string scenario from other proposals.

Possible evidence for MeV dark matter in dwarf spheroidals.

The observed 511 keV emission from the galactic bulge could be due to very light (MeV) annihilating dark matter particles. To distinguish this hypothesis from conventional astrophysical sources, we study dwarf spheroidals in the region observed by the International Gamma-Ray Astrophysics Laboratory/SPI such as Sagittarius. As these galaxies have comparatively few stars, the prospects for 511 keV emission from standard astrophysical scenarios are minimal. The dwarf spheroidals do, however, contain copious amounts of dark matter. The observation of 511 keV emission from Sagittarius should be a "smoking gun" for MeV dark matter.

Coordinación entre servicios de urgencias. Un modelo eficaz en la planificación sanitaria / Coordination among emergency services. An effective model for healthcare planning

Objetivo: Evaluar, mediante un estudio de intervención con controles históricos, la optimización del traslado de pacientes desde el servicio de urgencias de un hospital de alta complejidad -centro emisor (CE)- a un hospital de menor complejidad -centro receptor (CR)- durante el invierno. Material y método: La intervención consistió en la creación de los siguientes recursos y dispositivos: criterios de selección de pacientes aptos para ser trasladados, sistema exclusivo de comunicación, un horario de traslados, obtención de resultados pendientes de pruebas efectuadas en el CE, una unidad de hospitalización específica en el CR, circuito de altas y prealtas en el CR, normas escritas de coordinación entre la unidad asistencial, la Unidad de Trabajo Social y el Servicio de Farmacia Hospitalaria, hoja de acogida y un circuito de información a las residencias sanitarias. Resultados: Se trasladó a 247 pacientes. Ningún paciente permaneció en el área de urgencias del CR. No hubo ninguna desprogramación de ingresos en el CR. El índice de reingreso a los 30 días fue del 2,4 por ciento. La estancia media en el CR fue de 5,63 días. El índice funcional fue de 0,6; la razón de funcionamiento estándar, 0,6; la diferencia atribuible al funcionamiento, 4,0 y el impacto, 706.Conclusiones: La intervención en el traslado de pacientes desde un servicio de urgencias de un centro de alta complejidad a un centro de menor complejidad, para evitar el colapso del primero, mejora la calidad asistencial de los pacientes trasladados y evita mermar la del hospital receptor (AU)