The Jets of AGN as giant co-axial cables

The currents carried by the jets of active galactic nuclei (AGNs) can be probed using maps of the Faraday rotation measure (RM), since a jet current will be accompanied by a toroidal magnetic (B) field, which will give rise to a systematic change in the RM across the jet. The aim of this study is to identify new AGNs displaying statistically significant transverse RM gradients across their parsec-scale jets, and to look for overall patterns in the implied directions for the toroidal B-field components and jet currents. We have carried out new analyses of Faraday RM maps derived from previously published 8.1, 8.4, 12.1 and 15.3 GHz data obtained in 2006 on the NRAO VLBA. In a number of important ways, our procedures were identical to those of the original authors, but several other key aspects of the new imaging and analysis differ from the original methods. Our new analysis has substantially increased the number of AGNs known to display transverse RM gradients. The collected data on parsec and kiloparsec scales indicate that the current typically flows inward along the jet axis and outward in a more extended region surrounding the jet, typical to the current structure of a coaxial cable, accompanied by a self-consistent system of nested helical B fields, whose toroidal components give rise to the observed transverse RM gradients. These new results make it possible for the first time to conclusively demonstrate the existence of a preferred direction for the toroidal B-field components - and therefore of the currents - of AGN jets. Discerning the origin of this current-field system is of cardinal importance for understanding the physical mechanisms leading to the formation of the intrinsic jet B field, which likely plays an important role in the propagation and collimation of the jets; one possibility is the action of a "cosmic battery".Comment: 12 pages, 2 figures, 3 tables; accepted for publication in Astronomy & Astrophysic

ADR-based Workplace Conflict Management Systems: A Case of American Exceptionalism

[Excerpt] The diffusion of ADR-based conflict management systems is a development increasingly highlighted in the literature. Organizations are seen as putting in place multiple procedures and practices so that different varieties of workplace conflict can be effectively addressed. Just why organizations are electing to introduce these integrated bundles of innovative conflict management practices is a matter of debate, but many view the development as transforming the manner in which workplace problems are managed in modern organizations, with some even pronouncing that it amounts to the rewriting of the social contract at work (Lipsky and Seeber 2006). This paper argues that to the extent to which conflict management systems are being diffused, it is occurring mainly in the USA became the institutional context for the management of the employment relationship creates considerable incentives for the adoption of ADR-inspired conflict management innovations. Other Anglo-American countries, where it might be thought reasonable to expect a similar pattern of ADR innovation at the workplace to emerge, are not experiencing any discernible shift towards conflict management systems inside organizations. It is suggested that in the absence of institutional incentives to adopt workplace management systems, organizations are unlikely to opt for radical conflict management innovations. At the same time, drawing on research in the Irish context, it is argued that tried-and-tested conflict management practices do change over time, with an incremental and evolutionary approach adopted by some organizations to upgrade practices considered the most interesting development. The paper is organized as follows. The first section assesses why the emergence of integrated conflict management systems in organizations is considered to be a significant new development in the USA. The next section evaluates evidence and suggests that a similar pattern of workplace conflict management innovation is not occurring in other Anglo-American countries. After this evaluation, it is suggested that the institutional context in the USA creates uniquely strong incentives for organizations to adopt integrated bundles of ADR practices at the workplace - causing the emergence of conflict management systems to be a case of ‘American exceptionalism’. The following section argues that in the absence of strong institutional incentives to do so, organizations are unlikely to move radically away from established conflict management systems. The penultimate section explains that even in the presence of organizational inertia, conflict management practices seldom stay the same and uses research in the Irish context to suggest that organizations sometimes use an evolutionary approach to upgrade conflict management practices in an incremental yet continuous manner. The final section presents a number of case studies of this evolutionary approach to conflict management innovation. The conclusions bring together the arguments of the paper

Prior exercise speeds pulmonary oxygen uptake kinetics and increases critical power during supine but not upright cycling

Critical power (CP) is a fundamental parameter defining high-intensity exercise tolerance and is related to the time constant of phase II pulmonary oxygen uptake kinetics (τV̇O2). To test the hypothesis that this relationship is causal we determined the impact of prior exercise (“priming”) on CP and τV̇O2 in the upright and supine positions. 17 healthy men were assigned to either upright or supine exercise groups, whereby CP, τV̇O2 and muscle deoxyhaemoglobin kinetics (τ[HHb]) were determined via constant-power tests to exhaustion at four work-rates with (primed) and without (control) priming exercise at ∼31%Δ. During supine exercise, priming reduced τV̇O2 (control: 54 ± 18 vs. primed: 39 ± 11 s; P < 0.001), increased τ[HHb] (control: 8 ± 4 vs. primed: 12 ± 4 s; P = 0.003) and increased CP (control: 177 ± 31 vs. primed: 185 ± 30 W, P = 0.006) compared to control. However, priming exercise had no effect on τV̇O2 (control: 37 ± 12 vs. primed: 35 ± 8 s; P = 0.82), τ[HHb] (CON: 10 ± 5 s vs. PRI: 14 ± 10; P = 0.10), or CP (control: 235 ± 42 vs. primed: 232 ± 35 W; P = 0.57) during upright exercise. The concomitant reduction of τV̇O2 and increased CP following priming in the supine group, effects that were absent in the upright group, provides the first experimental evidence that τV̇O2 is mechanistically related to critical power. The increased τ[HHb] suggests that this effect was mediated, at least in part, by improved oxygen availability

EFFECT OF HYPEROXIA ON CRITICAL POWER AND V ̇O2 KINETICS DURING UPRIGHT CYCLING

Introduction/Purpose: Critical power (CP) is a fundamental parameter defining high-intensity exercise tolerance, however its physiological determinants are incompletely understood. The present study determined the impact of hyperoxia on CP, the time constant of phase II pulmonary oxygen uptake kinetics (τ_V ̇ O2), and muscle oxygenation (assessed by near-infrared spectroscopy) in 9 healthy men performing upright cycle ergometry. Methods: CP was determined in normoxia and hyperoxia (fraction of inspired O2 = 0.5) via 4 severe-intensity constant load exercise tests to exhaustion on a cycle ergometer, repeated once in each condition. During each test, τ_V ̇ O2 and the time constant of muscle deoxyhaemoglobin kinetics (τ[HHb]), alongside absolute concentrations of muscle oxyhaemoglobin ([HbO2]), were determined. Results: CP was greater (hyperoxia: 216 ± 30 vs. normoxia: 197 ± 29W; P < 0.001) whereas W’ was reduced (hyperoxia: 15.4 ± 5.2 kJ, normoxia: 17.5 ± 4.3 W; P = 0.037) in hyperoxia compared to normoxia. τ_V ̇ O2 (hyperoxia: 35 ± 12 vs normoxia: 33 ± 10 s; P = 0.33) and τ[HHb] (hyperoxia: 11 ± 5 vs. normoxia: 14 ± 5 s; P = 0.65) were unchanged between conditions, whereas [HbO2] during exercise was greater in hyperoxia compared to normoxia (hyperoxia: 73 ± 20 vs. normoxia: 66 ± 15 μM; P = 0.001). Conclusion: This study provides novel insights into the physiological determinants of CP and by extension, exercise tolerance. Microvascular oxygenation and CP were improved during exercise in hyperoxia compared with normoxia. Importantly, the improved microvascular oxygenation afforded by hyperoxia did not alter τ_V ̇ O2, suggesting that microvascular O2 availability is an independent determinant of the upper limit for steady-state exercise, i.e. CP

Evaluating the progressive cardiovascular health benefits of short term high intensity interval training

Purpose High-intensity training is recognised as a time-efficient way of improving aerobic fitness. However, there is a lack of consensus regarding the temporal nature of adaptation response and which peripheral and cardiac changes occur using the same exercise stimulus and protocol. Therefore, this study aimed to evaluate the progression of vascular and cardiac changes over a 6-week training period. Methods Twelve healthy males (age 21 ± 2 years; 42.5 ± 8.3 ml min−1 kg−1) participated in a high-intensity training programme consisting of 1-min sprints, interspersed with 2 min active recovery, 3 days/week for 6 weeks on a cycle ergometer. Cardiac, vascular, blood lipids and VO2max measurements were taken at 0, 3 and 6 weeks and compared against a participant matched control group (age 21 ± 2 years; 37.7 ± 8.3 ml min−1 kg−1). Results There was a significant improvement in VO2max (42.5 ± 8.3–47.4 ± 8.5 ml min−1 kg−1; p = 0.009) in the training group and a significant decrease in systolic blood pressure (8%) from 0 to 6 weeks (p = 0.025). There was a small yet significant decrease in ejection fraction and increased end-systolic volume in both groups over time (p = 0.01) with no significant interaction effect (p > 0.05). A between-group difference in peak velocity of early diastolic mitral annular motion was also observed (p = 0.01). No improvements were seen in blood lipid profiles, central arterial stiffness and cardiometabolic risk score. Conclusions Six weeks of high-intensity training increases aerobic fitness and is enough to stimulate initial reductions in peripheral pressure, but not sufficient to elicit structural and functional cardiac changes, reduce arterial stiffness or lower CV risk

“Not Tied Up Neatly with a Bow”: Professionals’ Challenging Cases in Informed Consent for Genomic Sequencing

As the use of genomic technology has expanded in research and clinical settings, issues surrounding informed consent for genome and exome sequencing have surfaced. Despite the importance of informed consent, little is known about the specific challenges that professionals encounter when consenting patients or research participants for genomic sequencing. We interviewed 29 genetic counselors and research coordinators with considerable experience obtaining informed consent for genomic sequencing to understand their experiences and perspectives. As part of this interview, 24 interviewees discussed an informed consent case they found particularly memorable or challenging. We analyzed these case examples to determine the primary issue or challenge represented by each case. Challenges fell into two domains: participant understanding, and facilitating decisions about testing or research participation. Challenges related to participant understanding included varying levels of general and genomic literacy, difficulty managing participant expectations, and contextual factors that impeded participant understanding. Challenges related to facilitating decision-making included complicated family dynamics such as disagreement or coercion, situations in which it was unclear whether sequencing research would be a good use of participant time or resources, and situations in which the professional experienced disagreement or discomfort with participant decisions. The issues highlighted in these case examples are instructive in preparing genetics professionals to obtain informed consent for genomic sequencing

LIMITATIONS TO EXERCISE TOLERANCE IN TYPE 1 DIABETES: THE ROLE OF PULMONARY OXYGEN UPTAKE KINETICS AND PRIMING EXERCISE

We compared the time constant (τ_V ̇ O2) of the fundamental phase of pulmonary oxygen uptake (V ̇O2) kinetics between young adult males with type 1 diabetes and healthy controls. We also assessed the impact of priming exercise on τ_V ̇ O2, critical power, and muscle deoxygenation in a subset of participants with type 1 diabetes. 17 males with type 1 diabetes and 17 healthy male controls performed moderate-intensity exercise to determine τ_V ̇ O2. A subset of 7 participants with type 1 diabetes performed an additional eight visits, whereby critical power, τ_V ̇ O2 and muscle deoxyhaemoglobin + myoglobin ([HHb+Mb]; via near-infrared spectroscopy) kinetics (described by a time constant, τ[HHb+Mb]) were determined with (PRI) and without (CON) a prior 6-minute bout of heavy exercise. τ_V ̇ O2 was greater in participants with type 1 diabetes compared to controls (type 1 diabetes: 50±13 vs. control: 32±12 s; P<0.001). Critical power was greater in PRI compared to CON (PRI: 161±25 W vs. CON: 149±22 W; P<0.001), whereas τ_V ̇ O2 (PRI: 36±15 vs. CON: 50±21 s; P=0.006) and τ[HHb+Mb] (PRI: 10±5 vs. CON: 17±11 s; P=0.037) were reduced in PRI compared to CON. Type 1 diabetes patients showed slower pulmonary V ̇O2 kinetics when compared to controls; priming exercise speeded V ̇O2 and [HHb + Mb] kinetics, and increased critical power in a subgroup with type 1 diabetes. These data therefore represent the first characterisation of the power-duration relationship in type 1 diabetes, and the first experimental evidence that τ_V ̇ O2 is an independent determinant of critical power in this population