Neutrino Capture and r-Process Nucleosynthesis

We explore neutrino capture during r-process nucleosynthesis in neutrino-driven ejecta from nascent neutron stars. We focus on the interplay between charged-current weak interactions and element synthesis, and we delineate the important role of equilibrium nuclear dynamics. During the period of coexistence of free nucleons and light and/or heavy nuclei, electron neutrino capture inhibits the r-process. At all stages, capture on free neutrons has a larger impact than capture on nuclei. However, neutrino capture on heavey nuclei by itself, if it is very strong, is also detrimental to the r-process until large nuclear equilibrium clusters break down and the classical neutron-capture phase of the r-process begins. The sensitivity of the r-process to neutrino irradiation means that neutrino-capture effects can strongly constrain the r-process site, neutrino physics, or both. These results apply also to r-process scenarios other than neutrino-heated winds.Comment: 20 pages, 17 figures, Submitted to Physical Review

Evidence for an Intense Neutrino Flux during rr-Process Nucleosynthesis?

We investigate the possibility that neutrino capture on heavy nuclei competes with beta decay in the environment where the $r$-Process elements are synthesized. We find that such neutrino capture is not excluded by existing abundance determinations. We show that inclusion of significant neutrino capture on the (neutron number) N=82 waiting point nuclei can allow the inferred abundances of these species to provide a good fit to steady weak (beta decay plus neutrino capture) flow equilibrium. In fact, for particular choices of neutrino flux conditions, this fit is improved over the case where nuclei change their charge by beta decay alone. However, this improved fit can be realized only if neutrino capture plays a negligible role in nuclear decay back toward stability. We discuss the implications of these considerations for current proposed sites and models for $r$-Process nucleosynthesis.Comment: 10 pages, plain tex, submitted to ApJ

Final Report: 2nd US-India Network Enabled Research Collaboration Workshop

This 2nd US-India Network-enabled Research Collaboration Workshop built on the results and follow-up from the first workshop by identifying how problems and opportunities of network-enabled research collaboration presented in Delhi have been addressed; illustrating what new collaboration opportunities (and problems) have presented themselves and how they might be addressed; and posing the question - if network-enabled research collaboration dialogue has value, how do we proceed forward in a sustainable manner?Indiana University gratefully acknowledges the support of the US National Science Foundation via award OISE 0960487, and Indiana University and ERNET India gratefully acknowledge the support of the Indo-US Science and Technology Forum via award 110-2911-WS

Weak Charge-Changing Flow in Expanding r-Process Environments

We assess the prospects for attaining steady nuclear flow equilibrium in expanding r-process environments where beta decay and/or neutrino capture determine the nuclear charge-changing rates. For very rapid expansions, we find that weak steady flow equilibrium normally cannot be attained. However, even when neutron capture processes freeze out in such nonequilibrium conditions, abundance ratios of nuclear species in the r-process peaks might still mimic those attained in weak steady flow. This result suggests that the r-process yield in a regime of rapid expansion can be calculated reliably only when all neutron capture, photodisintegration, and weak interaction processes are fully coupled in a dynamical calculation. We discuss the implications of these results for models of the r-process sited in rapidly expanding neutrino-heated ejecta.Comment: 21 pages, AAS LaTex, 2 postscript figure

Can a Large Neutron Excess Help Solve the Baryon Loading Problem in Gamma-Ray Burst Fireballs?

We point out that the baryon-loading problem in Gamma-Ray Burst (GRB) models can be amelioriated if a significant fraction of the baryons which inertially confine the fireball are converted to neutrons. A high neutron fraction in some circumstances can result in a reduced transfer of energy from relativistic light particles in the fireball to baryons. The energy needed to produce the required relativistic flow in the GRB is consequently reduced, in some cases by orders of magnitude. This could be relevant to GRB models because a high neutron-to-proton ratio has been calculated in neutron star-merger fireball environments. Significant neutron excess also could occur near compact objects with high neutrino fluxes.Comment: 5 pages, 2 figures, to appear in Phys. Rev. Let

Sterile neutrinos and supernova nucleosynthesis

A light sterile neutrino species has been introduced to explain simultaneously the solar and atmospheric neutrino puzzles and the results of the LSND experiment, while providing for a hot component of dark matter. Employing this scheme of neutrino masses and mixings, we show how matter-enhanced active-sterile neutrino transformation followed by active-active neutrino transformation can solve robustly the neutron deficit problem encountered by models of r-process nucleosynthesis associated with neutrino-heated supernova ejecta.Comment: 29 pages, 3 postscript figures, submitted to Phys. Rev.

Effectiveness of advance care planning with family carers in dementia nursing homes:a paired cluster randomized controlled trial

BackgroundIn dementia care, a large number of treatment decisions are made by family carers on behalf of their family member who lacks decisional capacity; advance care planning can support such carers in the decision-making of care goals. However, given the relative importance of advance care planning in dementia care, the prevalence of advance care planning in dementia care is poor. AimTo evaluate the effectiveness of advance care planning with family carers in dementia care homes. DesignPaired cluster randomized controlled trial. The intervention comprised a trained facilitator, family education, family meetings, documentation of advance care planning decisions and intervention orientation for general practitioners and nursing home staff. Setting/participantsA total of 24 nursing homes with a dementia nursing category located in Northern Ireland, United Kingdom. Family carers of nursing home residents classified as having dementia and judged as not having decisional capacity to participate in advance care planning discussions. ResultsThe primary outcome was family carer uncertainty in decision-making about the care of the resident (Decisional Conflict Scale). There was evidence of a reduction in total Decisional Conflict Scale score in the intervention group compared with the usual care group (−10.5, 95% confidence interval: −16.4 to −4.7; p < 0.001). ConclusionAdvance care planning was effective in reducing family carer uncertainty in decision-making concerning the care of their family member and improving perceptions of quality of care in nursing homes. Given the global significance of dementia, the implications for clinicians and policy makers include them recognizing the importance of family carer education and improving communication between family carers and formal care providers

Self-monitoring of blood pressure in hypertension: A systematic review and individual patient data meta-analysis.

BACKGROUND: Self-monitoring of blood pressure (BP) appears to reduce BP in hypertension but important questions remain regarding effective implementation and which groups may benefit most. This individual patient data (IPD) meta-analysis was performed to better understand the effectiveness of BP self-monitoring to lower BP and control hypertension. METHODS AND FINDINGS: Medline, Embase, and the Cochrane Library were searched for randomised trials comparing self-monitoring to no self-monitoring in hypertensive patients (June 2016). Two reviewers independently assessed articles for eligibility and the authors of eligible trials were approached requesting IPD. Of 2,846 articles in the initial search, 36 were eligible. IPD were provided from 25 trials, including 1 unpublished study. Data for the primary outcomes-change in mean clinic or ambulatory BP and proportion controlled below target at 12 months-were available from 15/19 possible studies (7,138/8,292 [86%] of randomised participants). Overall, self-monitoring was associated with reduced clinic systolic blood pressure (sBP) compared to usual care at 12 months (-3.2 mmHg, [95% CI -4.9, -1.6 mmHg]). However, this effect was strongly influenced by the intensity of co-intervention ranging from no effect with self-monitoring alone (-1.0 mmHg [-3.3, 1.2]), to a 6.1 mmHg (-9.0, -3.2) reduction when monitoring was combined with intensive support. Self-monitoring was most effective in those with fewer antihypertensive medications and higher baseline sBP up to 170 mmHg. No differences in efficacy were seen by sex or by most comorbidities. Ambulatory BP data at 12 months were available from 4 trials (1,478 patients), which assessed self-monitoring with little or no co-intervention. There was no association between self-monitoring and either lower clinic or ambulatory sBP in this group (clinic -0.2 mmHg [-2.2, 1.8]; ambulatory 1.1 mmHg [-0.3, 2.5]). Results for diastolic blood pressure (dBP) were similar. The main limitation of this work was that significant heterogeneity remained. This was at least in part due to different inclusion criteria, self-monitoring regimes, and target BPs in included studies. CONCLUSIONS: Self-monitoring alone is not associated with lower BP or better control, but in conjunction with co-interventions (including systematic medication titration by doctors, pharmacists, or patients; education; or lifestyle counselling) leads to clinically significant BP reduction which persists for at least 12 months. The implementation of self-monitoring in hypertension should be accompanied by such co-interventions

The increase in pulmonary arterial pressure caused by hypoxia depends on iron status

Hypoxia is a major cause of pulmonary hypertension. Gene expression activated by the transcription factor hypoxia-inducible factor (HIF) is central to this process. The oxygen-sensing iron-dependent dioxygenase enzymes that regulate HIF are highly sensitive to varying iron availability. It is unknown whether iron similarly influences the pulmonary vasculature. This human physiology study aimed to determine whether varying iron availability affects pulmonary arterial pressure and the pulmonary vascular response to hypoxia, as predicted biochemically by the role of HIF. In a controlled crossover study, 16 healthy iron-replete volunteers undertook two separate protocols. The ‘Iron Protocol’ studied the effects of an intravenous infusion of iron on the pulmonary vascular response to 8 h of sustained hypoxia. The ‘Desferrioxamine Protocol’ examined the effects of an 8 h intravenous infusion of the iron chelator desferrioxamine on the pulmonary circulation. Primary outcome measures were pulmonary artery systolic pressure (PASP) and the PASP response to acute hypoxia (ΔPASP), assessed by Doppler echocardiography. In the Iron Protocol, infusion of iron abolished or greatly reduced both the elevation in baseline PASP (P < 0.001) and the enhanced sensitivity of the pulmonary vasculature to acute hypoxia (P = 0.002) that are induced by exposure to sustained hypoxia. In the Desferrioxamine Protocol, desferrioxamine significantly elevated both PASP (P < 0.001) and ΔPASP (P = 0.01). We conclude that iron availability modifies pulmonary arterial pressure and pulmonary vascular responses to hypoxia. Further research should investigate the potential for therapeutic manipulation of iron status in the management of hypoxic pulmonary hypertensive disease