Abstract
Line locking (LL) of absorption-line systems is a clear signature of the dynamical importance of radiation-pressure force in driving astrophysical flows, with recent findings suggesting that ...it may be common in quasars exhibiting multiple intrinsic narrow absorption-line (NAL) systems. In this work, we probe the phase space conducive to LL and follow the detailed kinematics of those systems that may lock at the velocity separation of the C
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1548.19, 1550.77 doublet. We find that a small volume of the phase-phase admits LL, suggesting a high degree of fine-tuning between the physical properties of locked systems. The stability of LL against quasar luminosity variations is quantified with implications for the long-term variability amplitude of quasars and the velocity-separation statistic between multiple NAL systems. The high occurrence of LL by the C
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doublet implies that the hidden extreme-UV emission from quasars is unlikely to be significantly underestimated by current models. Further, the ratio of the LL velocity to the outflow velocity may serve as a powerful constraint on the composition of the accelerating medium. We conclude that LL poses significant challenges to current theories for the formation of nonintervening NAL systems, and speculate that it may be a manifestation of expanding circumstellar shells around asymptotic giant branch stars in the quasar-host bulge.
We introduce a new theoretical model to describe the emitting region in a blazar jet. We adopt a one-zone leptonic picture and construct the particle transport equation for a plasma blob experiencing ...low-energy, monoenergetic particle injection, energy-dependent particle escape, shock acceleration, adiabatic expansion, stochastic acceleration, synchrotron radiation, and external Compton radiation from the dust torus and broad-line region (BLR). We demonstrate that a one-zone leptonic model is able to explain the IR though -ray spectrum for 3C 279 in 2008-2009. We determine that the BLR seed photons cannot be adequately described by a single average distribution, but rather we find that a stratified BLR provides an improvement in the estimation of the distance of the emitting region from the black hole. We calculate that the jet is not always in equipartition between the particles and magnetic field and find that stochastic acceleration provides more energy to the particles than does shock acceleration, where the latter is also overshadowed by adiabatic losses. We further introduce a novel technique to implement numerical boundary conditions and determine the global normalization for the electron distribution, based on analysis of stiff ordinary differential equations. Our astrophysical results are compared with those obtained by previous authors.
ABSTRACT Electromagnetic radiation from blazar jets often displays strong variability, extending from radio to γ-ray frequencies. In a few cases, this variability has been characterized using Fourier ...time lags, such as those detected in the X-rays from Mrk 421 using BeppoSAX. The lack of a theoretical framework to interpret the data has motivated us to develop a new model for the formation of the X-ray spectrum and the time lags in blazar jets based on a transport equation including terms describing stochastic Fermi acceleration, synchrotron losses, shock acceleration, adiabatic expansion, and spatial diffusion. We derive the exact solution for the Fourier transform of the electron distribution and use it to compute the Fourier transform of the synchrotron radiation spectrum and the associated X-ray time lags. The same theoretical framework is also used to compute the peak flare X-ray spectrum, assuming that a steady-state electron distribution is achieved during the peak of the flare. The model parameters are constrained by comparing the theoretical predictions with the observational data for Mrk 421. The resulting integrated model yields, for the first time, a complete first-principles physical explanation for both the formation of the observed time lags and the shape of the peak flare X-ray spectrum. It also yields direct estimates of the strength of the shock and the stochastic magnetohydrodynamical wave acceleration components in the Mrk 421 jet.
There are inconsistencies in concept, criteria, practice, and documentation of brain death/death by neurologic criteria (BD/DNC) both internationally and within countries.
To formulate a consensus ...statement of recommendations on determination of BD/DNC based on review of the literature and expert opinion of a large multidisciplinary, international panel.
Relevant international professional societies were recruited to develop recommendations regarding determination of BD/DNC. Literature searches of the Cochrane, Embase, and MEDLINE databases included January 1, 1992, through April 2020 identified pertinent articles for review. Because of the lack of high-quality data from randomized clinical trials or large observational studies, recommendations were formulated based on consensus of contributors and medical societies that represented relevant disciplines, including critical care, neurology, and neurosurgery.
Based on review of the literature and consensus from a large multidisciplinary, international panel, minimum clinical criteria needed to determine BD/DNC in various circumstances were developed.
Prior to evaluating a patient for BD/DNC, the patient should have an established neurologic diagnosis that can lead to the complete and irreversible loss of all brain function, and conditions that may confound the clinical examination and diseases that may mimic BD/DNC should be excluded. Determination of BD/DNC can be done with a clinical examination that demonstrates coma, brainstem areflexia, and apnea. This is seen when (1) there is no evidence of arousal or awareness to maximal external stimulation, including noxious visual, auditory, and tactile stimulation; (2) pupils are fixed in a midsize or dilated position and are nonreactive to light; (3) corneal, oculocephalic, and oculovestibular reflexes are absent; (4) there is no facial movement to noxious stimulation; (5) the gag reflex is absent to bilateral posterior pharyngeal stimulation; (6) the cough reflex is absent to deep tracheal suctioning; (7) there is no brain-mediated motor response to noxious stimulation of the limbs; and (8) spontaneous respirations are not observed when apnea test targets reach pH <7.30 and Paco2 ≥60 mm Hg. If the clinical examination cannot be completed, ancillary testing may be considered with blood flow studies or electrophysiologic testing. Special consideration is needed for children, for persons receiving extracorporeal membrane oxygenation, and for those receiving therapeutic hypothermia, as well as for factors such as religious, societal, and cultural perspectives; legal requirements; and resource availability.
This report provides recommendations for the minimum clinical standards for determination of brain death/death by neurologic criteria in adults and children with clear guidance for various clinical circumstances. The recommendations have widespread international society endorsement and can serve to guide professional societies and countries in the revision or development of protocols and procedures for determination of brain death/death by neurologic criteria, leading to greater consistency within and between countries.
The broadband spectrum from the 2013 December 20 -ray flare from 3C 279 is analyzed with our previously developed one-zone blazar jet model. We are able to reproduce two spectral energy distributions ...(SEDs), a quiescent and flaring state, the latter of which had an unusual SED, with hard -ray spectrum, high Compton dominance, and short duration. Our model suggests that there is insufficient energy for a comparable X-ray flare to have occurred simultaneously, which is an important constraint given the lack of X-ray data. We show that first- and second-order Fermi acceleration are sufficient to explain the flare, and that magnetic reconnection is not needed. The model includes particle acceleration, escape, and adiabatic and radiative energy losses, including the full Compton cross section, and emission from the synchrotron, synchrotron self-Compton, and external Compton processes. We provide a simple analytic approximation to the electron distribution solution to the transport equation that may be useful for simplified modeling in the future.
We have previously published a technique for objective assessment of freezing of gait (FOG) in Parkinson's disease (PD) from a single shank-mounted accelerometer. Here we extend this approach to ...evaluate the optimal configuration of sensor placement and signal processing parameters using seven sensors attached to the lumbar back, thighs, shanks and feet.
Multi-segmental acceleration data was obtained from 25 PD patients performing 134 timed up and go tasks, and clinical assessment of FOG was performed by two experienced raters from video. Four metrics were used to compare objective and clinical measures; the intraclass correlation coefficient (ICC) for number of FOG episodes and the percent time frozen per trial; and the sensitivity and specificity of FOG detection.
The seven-sensor configuration was the most robust, scoring highly on all measures of performance (ICC number of FOG 0.75; ICC percent time frozen 0.80; sensitivity 84.3%; specificity 78.4%). A simpler single-shank sensor approach provided similar ICC values and exhibited a high sensitivity to FOG events, but specificity was lower at 66.7%. Recordings from the lumbar sensor offered only moderate agreement with the clinical raters in terms of absolute number and duration of FOG events (likely due to musculoskeletal attenuation of lower-limb 'trembling' during FOG), but demonstrated a high sensitivity (86.2%) and specificity (82.4%) when considered as a binary test for the presence/absence of FOG within a single trial.
The seven-sensor approach was the most accurate method for quantifying FOG, and is best suited to demanding research applications. A single shank sensor provided measures comparable to the seven-sensor approach but is relatively straightforward in execution, facilitating clinical use. A single lumbar sensor may provide a simple means of objective FOG detection given the ubiquitous nature of accelerometers in mobile telephones and other belt-worn devices.
Molecular‐based approaches for biological source identification are of great interest in the forensic community because of a lack of sensitivity and specificity in current methods. MicroRNAs (miRNAs) ...have been considered due to their robust nature and tissue specificity; however, analysis requires a separate RNA extraction, requiring an additional step in the forensic analysis workflow. The purpose of this study was to evaluate miRNA detection in blood, semen, and saliva using DNA extraction methods commonly utilized for forensic casework. RT‐qPCR analysis revealed that the tested miRNAs were consistently detectable across most tested DNA extraction methods, but detection was significantly reduced compared to RNA extracts in some biological fluids. DNase treatment was not necessary to achieve miRNA‐specific results. A previously developed miRNA panel for forensic body fluid identification was evaluated using DNA extracts, and largely demonstrated concordance with results from samples deriving from RNA extracts of semen, blood, and saliva.
Examine the changes in service delivery Australian public sexual health clinics made to remain open during lockdown.
A cross‐sectional survey designed and delivered on Qualtrics was emailed to 21 ...directors of public sexual health clinics across Australia from July‐August 2020 and asked about a variety of changes to service delivery. Descriptive statistics were calculated.
Twenty clinics participated, all remained open and reported service changes, including suspension of walk‐in services in eight clinics. Some clinics stopped offering asymptomatic screening for varying patient populations. Most clinics transitioned to a mix of telehealth and face‐to‐face consultations. Nineteen clinics reported delays in testing and 13 reported limitations in testing. Most clinics changed to phone consultations for HIV medication refills (n=15) and eleven clinics prescribed longer repeat prescriptions. Fourteen clinics had staff redeployed to assist the COVID‐19 response.
Public sexual health clinics pivoted service delivery to reduce risk of COVID‐19 transmission in clinical settings, managed staffing reductions and delays in molecular testing, and maintained a focus on urgent and symptomatic STI presentations and those at higher risk of HIV/STI acquisition.
Further research is warranted to understand what impact reduced asymptomatic screening may have had on community STI transmission.
Abstract Freezing of gait, a paroxysmal motor block, is common in the latter stages of Parkinson's disease. The current 'gold standard' of assessing the severity of freezing is based on clinical ...identification (by up to 3 raters) of the number of episodes from video. The aims of this study were to systematically assess this ‘gold standard’ across multiple Parkinson's disease centers, and to compare these clinical ratings with objective measures derived from lower limb acceleration data. Video recordings were acquired during a timed up-and-go task from 10 Parkinson's disease patients (with a clinical history of freezing) in the 'off' state. Patients were instrumented with accelerometers on the lateral aspect of each shank. Ten experienced clinicians were recruited from four Parkinson's disease centers to independently assess the videos for number and duration of freezing events. The reliability of clinical video assessment for number of freezing events was moderate (intraclass correlation coefficient 0.63). Percent time frozen (cumulative duration of freezing episodes/total duration of the walking task) demonstrated stronger agreement between raters (0.73). Agreement of accelerometry-derived measures of freezing severity with mean clinician ratings was strong for number of episodes (0.78) and very strong for percent time frozen (0.93). The results demonstrate the viability of objective measures of freezing, and that percent time frozen is a more reliable metric of severity than number of freezing events for both clinical and objective measures. The large variability between clinicians suggests that caution should be used when comparing subjective ratings across centers.
Evaluation of microRNA (miRNA) expression as a potential method for forensic body fluid identification has been the subject of investigation over the past several years. Because of their size and ...encapsulation within proteins and lipids, miRNAs are inherently less susceptible to degradation than other RNAs. In this work, blood, urine, semen, and saliva were exposed to environmental and chemical conditions mimicking sample compromise at the crime scene. For many treated samples, including 100% of blood samples, miRNAs remained detectable, comparable to the untreated control. Sample degradation varied by body fluid and treatment, with blood remarkably resistant, while semen and saliva are more susceptible to environmental insult. Body fluid identification using relative miRNA expression of blood and semen of the exposed samples was 100% and 94%, respectively. Given the overall robust results herein, the case is strengthened for the use of miRNAs as a molecular method for body fluid identification.
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