A retrospective study on the effects of illness severity and atrial fibrillation on outcomes in the intensive care unit

Introduction: Atrial fibrillation (AF) is common in patients in the intensive care unit (ICU) and has been associated with worse outcomes. However, it is unclear whether AF itself adds to the risk of death or is merely a marker of illness severity. We aimed to record the incidence and outcomes of all patients with different categories of AF and determine whether AF was an independent predictor of death.<p></p> Methods: This retrospective cohort study was undertaken in the ICU of a tertiary-referral university hospital. Category of AF, sex, C-reactive protein (CRP) level, APACHE II score, predicted hospital mortality and survival outcomes were analysed from 1084 records. Percentages, medians and interquartile ranges were used to describe the sample. Chi-square test and the non-parametric Mann–Whitney U test were used, as appropriate, for statistical analysis. Logistic regression analyses were performed to evaluate the association of AF with death in the ICU adjusting for age, sex, CRP level and APACHE II score.<p></p> Results: Overall, 13.6% of patients developed new-onset AF during their critical illness, while 4.3% had a pre-existing history. The hospital mortality rate was higher in those with AF compared with those without (47.9% vs. 30.9%, p<0.001) and higher in those with newly diagnosed AF compared with those with a prior history (53.1% vs. 31.9%, p=0.012). CRP levels were higher in those with AF (p<0.001) compared with those without and higher in those with newly diagnosed AF compared with those with a prior history (p=0.012). On multivariate logistic regression analysis, only the APACHE II score was found to be an independent predictor of death.<p></p> Conclusion: Despite the higher mortality rate in patients with AF, the APACHE II score was the only independent predictor of death within the ICU. Prospective studies are required to explore the apparently reduced risk of dying among those with a prior history of AF.<p></p&gt

Absolute emission altitude of pulsars: PSRs B1839+09, B1916+14 and B2111+46

We study the mean profiles of the multi--component pulsars PSRs B1839+09, B1916+14 and B2111+46. We estimate the emission height of the core components, and hence find the absolute emission altitudes corresponding to the conal components. By fitting Gaussians to the emission components, we determine the phase location of the component peaks. Our findings indicate that the emission beams of these pulsars have the nested core--cone structures. Based on the phase location of the component peaks, we estimate the aberration--retardation (A/R) phase shifts in the profiles. Due to the A/R phase shift, the peak of the core component in the intensity profile and the inflection point of the polarization angle swing are found to be symmetrically shifted in the opposite directions with respect to the meridional plane in such a way that the core shifts towards the leading side and the polarization angle inflection point towards the trailing side. We have been able to locate the phase location of the meridional plane and to estimate the absolute emission altitude of both the core and the conal components relative to the neutron star centre, using the exact expression for the A/R phase shift given by Gangadhara (2005).Comment: 10 pages, 6 figures, Accepted for Publication in A&

RF model of the distribution system as a communication channel, phase 2. Volume 3: Appendices

Program documentation concerning the design, implementation, and verification of a computerized model for predicting the steady-state sinusoidal response of radial configured distribution feeders is presented in these appendices

RF model of the distribution system as a communication channel, phase 2. Volume 4: Sofware source program and illustrations ASCII database listings

Listings of source programs and some illustrative examples of various ASCII data base files are presented. The listings are grouped into the following categories: main programs, subroutine programs, illustrative ASCII data base files. Within each category files are listed alphabetically

Optical signatures of auroral arcs produced by field line resonances: comparison with satellite observations and modeling

International audienceWe show two examples from the CANOPUS array of the optical signatures of auroral arcs produced by field line resonances on the night of 31 January 1997. The first example occurs during local evening at about 18:00 MLT (Magnetic Local Time), where CANOPUS meridian scanning photometer data show all the classic features of field line resonances. There are two, near-monochromatic resonances (at approximately 2.0 and 2.5 mHz) and both show latitudinal peaks in amplitude with an approximately 180 degree latitudinal phase shift across the maximum. The second field line resonance event occurs closer to local midnight, between approximately 22:00 and 22:40 MLT. Magnetometer and optical data show that the field line resonance has a very low frequency, near 1.3 mHz. All-sky imager data from CANOPUS show that in this event the field line resonances produce auroral arcs with westward propagation, with arc widths of about 10 km. Electron energies are on the order of 1 keV. This event was also seen in data from the FAST satellite (Lotko et al., 1998), and we compare our observations with those of Lotko et al. (1998). A remarkable feature of this field line resonance is that the latitudinal phase shift was substantially greater than 180 degrees. In our discussion, we present a model of field line resonances which accounts for the dominant physical effects and which is in good agreement with the observations. We emphasize three points. First, the low frequency of the field line resonance in the second event is likely due to the stretched topology of the magnetotail field lines, with the field line resonance on field lines threading the earthward edge of the plasma sheet. Second, the latitudinal phase structure may indicate dispersive effects due to electron trapping or finite ion gyroradius. Third, we show that a nonlocal conductivity model can easily explain the parallel electric fields and the precipitating electron energies seen in the field line resonance

Patients' request for and emergency physicians' prescription of antimicrobial prophylaxis for anthrax during the 2001 bioterrorism-related outbreak

BACKGROUND: Inappropriate use of antibiotics by individuals worried about biological agent exposures during bioterrorism events is an important public health concern. However, little is documented about the extent to which individuals with self-identified risk of anthrax exposure approached physicians for antimicrobial prophylaxis during the 2001 bioterrorism attacks in the United States. METHODS: We conducted a telephone survey of randomly selected members of the Pennsylvania Chapter of the American College of Emergency Physicians to assess patients' request for and emergency physicians' prescription of antimicrobial agents during the 2001 anthrax attacks. RESULTS: Ninety-seven physicians completed the survey. Sixty-four (66%) respondents had received requests from patients for anthrax prophylaxis; 16 (25%) of these physicians prescribed antibiotics to a total of 23 patients. Ten physicians prescribed ciprofloxacin while 8 physicians prescribed doxycycline. CONCLUSION: During the 2001 bioterrorist attacks, the majority of the emergency physicians we surveyed encountered patients who requested anthrax prophylaxis. Public fears may lead to a high demand for antibiotic prophylaxis during bioterrorism events. Elucidation of the relationship between public health response to outbreaks and outcomes would yield insights to ease burden on frontline clinicians and guide strategies to control inappropriate antibiotic allocation during bioterrorist events

The role of concussion history and biological sex on pupillary light reflex metrics in adolescent rugby players: a cross-sectional study.

Abstract: Background: Concussion examination is based primarily on clinical evaluation and symptomatic reporting. Pupillary light reflex (PLR) metrics may provide an objective physiological marker to inform concussion diagnosis and recovery, but few studies have assessed PLR, and normative data are lacking, particularly for adolescents. Aim: To capture PLR data in adolescent rugby players and examine the effects of concussion history and biological sex. Design: Cross‐sectional. Methods: Male and female adolescent rugby union players aged 16 to 18 years were recruited at the start of the 2022–2023 playing season. PLR was recorded using a handheld pupillometer which provided seven different metrics relating to pupil diameter, constriction/dilation latency, and velocity. Data were analysed using a series of 2 × 2 ANOVAs to examine the main effects of independent variables: biological sex, concussion history, and their interactions, using adjusted p‐values (p < 0.05). Results: 149 participants (75% male) were included. A total of 42% reported at least one previous concussion. Most metrics were unaffected by the independent variables. There were however significant main effects for concussion history (F = 4.11 (1); p = 0.05) and sex (F = 5.42(1); p = 0.02) in end pupil diameters, and a main effect for sex in initial pupil diameters (F = 4.45 (1); p = 0.04). Although no significant interaction effects were found, on average, females with a concussion history presented with greater pupillary diameters and velocity metrics, with many pairwise comparisons showing large effects (SMD > 0.8). Conclusions: Pupillary diameters in adolescent athletes were significantly affected by concussion history and sex. The most extreme PLRmetrics were recorded in females with a history of concussion (higher pupillary diameters and velocities). This highlights the importance of establishing baseline PLR metrics prior to interpretation of the PLR post‐concussion. Long‐standing PLR abnormalities post‐concussion may reflect ongoing autonomic nervous system dysfunction. This warrants further investigation in longitudinal studies

A retrospective study on the effects of illness severity and atrial fibrillation on outcomes in the intensive care unit

Introduction: Atrial fibrillation (AF) is common in patients in the intensive care unit (ICU) and has been associated with worse outcomes. However, it is unclear whether AF itself adds to the risk of death or is merely a marker of illness severity. We aimed to record the incidence and outcomes of all patients with different categories of AF and determine whether AF was an independent predictor of death.<p></p> Methods: This retrospective cohort study was undertaken in the ICU of a tertiary-referral university hospital. Category of AF, sex, C-reactive protein (CRP) level, APACHE II score, predicted hospital mortality and survival outcomes were analysed from 1084 records. Percentages, medians and interquartile ranges were used to describe the sample. Chi-square test and the non-parametric Mann–Whitney U test were used, as appropriate, for statistical analysis. Logistic regression analyses were performed to evaluate the association of AF with death in the ICU adjusting for age, sex, CRP level and APACHE II score.<p></p> Results: Overall, 13.6% of patients developed new-onset AF during their critical illness, while 4.3% had a pre-existing history. The hospital mortality rate was higher in those with AF compared with those without (47.9% vs. 30.9%, p<0.001) and higher in those with newly diagnosed AF compared with those with a prior history (53.1% vs. 31.9%, p=0.012). CRP levels were higher in those with AF (p<0.001) compared with those without and higher in those with newly diagnosed AF compared with those with a prior history (p=0.012). On multivariate logistic regression analysis, only the APACHE II score was found to be an independent predictor of death.<p></p> Conclusion: Despite the higher mortality rate in patients with AF, the APACHE II score was the only independent predictor of death within the ICU. Prospective studies are required to explore the apparently reduced risk of dying among those with a prior history of AF.<p></p&gt

Stokes tomography of radio pulsar magnetospheres. I. Linear polarization

Polarimetric studies of pulsar radio emission traditionally concentrate on how the Stokes vector (I, Q, U, V) varies with pulse longitude, with special emphasis on the position angle (PA) swing of the linearly polarized component. The interpretation of the PA swing in terms of the rotating vector model is limited by the assumption of an axisymmetric magnetic field and the degeneracy of the output with respect to the orientation and magnetic geometry of the pulsar; different combinations of the latter two properties can produce similar PA swings. This paper introduces Stokes phase portraits as a supplementary diagnostic tool with which the orientation and magnetic geometry can be inferred more accurately. The Stokes phase portraits feature unique patterns in the I-Q, I-U, and Q-U planes, whose shapes depend sensitively on the magnetic geometry, inclination angle, beam and polarization patterns, and emission altitude. We construct look-up tables of Stokes phase portraits and PA swings for pure and current-modified dipole fields, filled core and hollow cone beams, and two empirical linear polarization models, L/I = \cos \theta_0 and L/I = \sin \theta_0, where \theta_0 is the colatitude of the emission point. We compare our look-up tables to the measured phase portraits of 24 pulsars in the European Pulsar Network online database. We find evidence in 60% of the objects that the radio emission region may depart significantly from low altitudes, even when the PA swing is S-shaped and/or the pulse-width-period relation is well satisfied. On the other hand, the data are explained adequately if the emission altitude exceeds ~10% of the light cylinder radius. We conclude that Stokes phase portraits should be analysed concurrently with the PA swing and pulse profiles in future when interpreting radio pulsar polarization data.Comment: 60 pages, 58 figures, submitted to MNRAS, accepted 13 Oct 201