Multiphase PC/PL Relations: Comparison between Theory and observations

Cepheids are fundamental objects astrophysically in that they hold the key to a CMB independent estimate of Hubble's constant. A number of researchers have pointed out the possibilities of breaking degeneracies between Omega_Matter and H0 if there is a CMB independent distance scale accurate to a few percent (Hu 2005). Current uncertainties in the distance scale are about 10% but future observations, with, for example, the JWST, will be capable of estimating H0 to within a few percent. A crucial step in this process is the Cepheid PL relation. Recent evidence has emerged that the PL relation, at least in optical bands, is nonlinear and that neglect of such a nonlinearity can lead to errors in estimating H0 of up to 2 percent. Hence it is important to critically examine this possible nonlinearity both observationally and theoretically. Existing PC/PL relations rely exclusively on evaluating these relations at mean light. However, since such relations are the average of relations at different phases. Here we report on recent attempts to compare theory and observation in the multiphase PC/PL planes. We construct state of the art Cepheid pulsations models appropriate for the LMC/Galaxy and compare the resulting PC/PL relations as a function of phase with observations. For the LMC, the (V-I) period-color relation at minimum light can have quite a narrow dispersion (0.2-0.3 mags) and thus could be useful in placing constraints on models. At longer periods, the models predict significantly redder (by about 0.2-0.3 mags) V-I colors. We discuss possible reasons for this and also compare PL relations at various phases of pulsation and find clear evidence in both theory and observations for a nonlinear PL relation.Comment: 5 pages, 8 figures, proceeding for "Stellar Pulsation: Challenges for Theory and Observation", Santa Fe 200

Stochastic Processes in Yellow and Red Pulsating Variables

Random changes in pulsation period are well established in cool pulsating stars, in particular the red giant variables: Miras, semi-regulars of types A and B, and RV Tau variables. Such effects are also observed in a handful of Cepheids, the SX Phe variable XX Cyg, and, most recently, the red supergiant variable, BC Cyg, a type C semi-regular. The nature of such fluctuations is seemingly random over a few pulsation cycles of the stars, yet the regularity of the primary pulsation mechanism dominates over the long term. The degree of stochasticity is linked to the dimensions of the stars, the randomness parameter 'e' appearing to correlate closely with mean stellar radius through the period 'P', with an average value of e/P = 0.0136+-0.0005. The physical processes responsible for such fluctuations are uncertain, but presumably originate in temporal modifications of envelope convection in such stars.Comment: Poster given at the "Stellar Pulsation: Challenges for Theory and Observation" conference in Santa Fe, New Mexico (2009

Understanding the information needs of public health practitioners: A literature review to inform design of an interactive digital knowledge management system

AbstractThe need for rapid access to information to support critical decisions in public health cannot be disputed; however, development of such systems requires an understanding of the actual information needs of public health professionals. This paper reports the results of a literature review focused on the information needs of public health professionals. The authors reviewed the public health literature to answer the following questions: (1) What are the information needs of public health professionals? (2) In what ways are those needs being met? (3) What are the barriers to meeting those needs? (4) What is the role of the Internet in meeting information needs? The review was undertaken in order to develop system requirements to inform the design and development of an interactive digital knowledge management system. The goal of the system is to support the collection, management, and retrieval of public health documents, data, learning objects, and tools.Method:The search method extended beyond traditional information resources, such as bibliographic databases, tables of contents (TOC), and bibliographies, to include information resources public health practitioners routinely use or have need to use—for example, grey literature, government reports, Internet-based publications, and meeting abstracts.Results:Although few formal studies of information needs and information-seeking behaviors of public health professionals have been reported, the literature consistently indicated a critical need for comprehensive, coordinated, and accessible information to meet the needs of the public health workforce. Major barriers to information access include time, resource reliability, trustworthiness/credibility of information, and “information overload”.Conclusions:Utilizing a novel search method that included the diversity of information resources public health practitioners use, has produced a richer and more useful picture of the information needs of the public health workforce than other literature reviews. There is a critical need for public health digital knowledge management systems designed to reflect the diversity of public health activities, to enable human communications, and to provide multiple access points to critical information resources. Public health librarians and other information specialists can serve a significant role in helping public health professionals meet their information needs through the development of evidence-based decision support systems, human-mediated expert searching and training in the use information retrieval systems

Evidence for Black Hole Growth in Local Analogs to Lyman Break Galaxies

We have used XMM-Newton to observe six Lyman Break Analogs (LBAs): members of the rare population of local galaxies that have properties that are very similar to distant Lyman Break Galaxies. Our six targets were specifically selected because they have optical emission-line properties that are intermediate between starbursts and Type 2 (obscured) AGN. Our new X-ray data provide an important diagnostic of the presence of an AGN. We find X-ray luminosities of order 10^{42} erg/s and ratios of X-ray to far-IR luminosities that are higher than values in pure starburst galaxies by factors ranging from ~ 3 to 30. This strongly suggests the presence of an AGN in at least some of the galaxies. The ratios of the luminosities of the hard (2-10 keV) X-ray to [O III]\lambda 5007 emission-line are low by about an order-of-magnitude compared to Type 1 AGN, but are consistent with the broad range seen in Type 2 AGN. Either the AGN hard X-rays are significantly obscured or the [O III] emission is dominated by the starburst. We searched for an iron emission line at ~ 6.4 keV, which is a key feature of obscured AGN, but only detected emission at the ~ 2\sigma level. Finally, we find that the ratios of the mid-infrared (24\mu m) continuum to [O III]\lambda 5007 luminosities in these LBAs are higher than the values for Type 2 AGN by an average of 0.8 dex. Combining all these clues, we conclude that an AGN is likely to be present, but that the bolometric luminosity is produced primarily by an intense starburst. If these black holes are radiating at the Eddington limit, their masses would lie in the range of 10^5 to 10^6 M_{sun}. These objects may offer ideal local laboratories to investigate the processes by which black holes grew in the early universe.Comment: Accepted for publication in Ap

A Wide Field Survey of Satellite Galaxies around the Spiral Galaxy M106

We present a wide field survey of satellite galaxies in M106 (NGC 4258) covering a 1.7\degr \times 2\degr field around M106 using Canada-France-Hawaii Telescope/MegaCam. We find 16 satellite galaxy candidates of M106. Eight of these galaxies are found to be dwarf galaxies that are much smaller and fainter than the remaining galaxies. Four of these galaxies are new findings. Surface brightness profiles of 15 out of 16 satellite galaxies can be represented well by an exponential disk profile with varying scale length. We derive the surface number density distribution of these satellite galaxies. The central number density profile (d $<100$ kpc) is well fitted by a power-law with a power index of $-2.1\pm0.5$, similar to the expected power index of isothermal distribution. The luminosity function of these satellites is represented well by the Schechter function with a faint end slope of $-1.19^{+0.03}_{-0.06}$. Integrated photometric properties (total luminosity, total colour, and disk scale length) and the spatial distribution of these satellite galaxies are found to be roughly similar to those of the Milky Way and M31.Comment: Accepted by MNRA

Risk of non-Hodgkin lymphoma associated with occupational exposure to solvents,metals, organic dusts and PCBs (Australia)

Objective: Several studies have suggested that there is an occupational component to the causation of non-Hodgkin lymphoma (NHL). We aimed to use accurate means to assess occupational exposures to solvents, metals, organic dusts and polychlorinated biphenyls (PCBs) in a case-control study. Methods: Cases were incident NHLs during 2000 and 2001 in two regions of Australia. Controls were randomly selected from the electoral roll and frequency matched to cases by age, sex and region. A detailed occupational history was taken from each subject. For jobs with likely exposure to the chemicals of interest, additional questions were asked by telephone interview using modified job specific modules. An expert allocated exposures using the information in the job histories and the interviews. Odds ratios were calculated for each exposure adjusting for age, sex, region and ethnic origin. Results: 694 cases and 694 controls (70% and 45% respectively of those potentially eligible) participated. The risk of NHL was increased by about 30% for exposure to any solvent with a dose response relationship, subgroup analysis showed the finding was restricted to solvents other than benzene. Exposure to wood dust also increased the risk of NHL slightly. Exposures to other organic dusts, metals, and PCBs were not strongly related to NHL. Conclusions: The risk of NHL appears to be increased by exposure to solvents other than benzene and possibly to wood dust

Using multi-criteria decision analysis to describe stakeholder preferences for new quality improvement initiatives that could optimise prescribing in England

Background: Hospital decision-makers have limited resources to implement quality improvement projects. To decide which interventions to take forward, trade-offs must be considered that inevitably turn on stakeholder preferences. The multi-criteria decision analysis (MCDA) approach could make this decision process more transparent.  Method: An MCDA was conducted to rank-order four types of interventions that could optimise medication use in England's National Healthcare System (NHS) hospitals, including Computerised Interface, Built Environment, Written Communication, and Face-to-Face Interactions. Initially, a core group of quality improvers (N = 10) was convened to determine criteria that could influence which interventions are taken forward according to the Consolidated Framework for Implementation Research. Next, to determine preference weightings, a preference survey was conducted with a diverse group of quality improvers (N = 356) according to the Potentially All Pairwise Ranking of All Possible Alternatives method. Then, rank orders of four intervention types were calculated according to models with criteria unweighted and weighted according to participant preferences using an additive function. Uncertainty was estimated by probabilistic sensitivity analysis using 1,000 Monte Carlo Simulation iterations.  Results: The most important criteria influencing what interventions were preferred was whether they addressed "patient needs" (17.6%)' and their financial "cost (11.5%)". The interventions' total scores (unweighted score out of 30 | weighted out of 100%) were: Computerised Interface (25 | 83.8%), Built Environment (24 | 79.6%), Written Communication (22 | 71.6%), and Face-to-Face (22 | 67.8%). The probabilistic sensitivity analysis revealed that the Computerised Interface would be the most preferred intervention over various degrees of uncertainty.  Conclusions: An MCDA was conducted to rank order intervention types that stand to increase medication optimisation across hospitals in England. The top-ranked intervention type was the Computerised Interface. This finding does not imply Computerised Interface interventions are the most effective interventions but suggests that successfully implementing lower-ranked interventions may require more conversations that acknowledge stakeholder concerns

Development and performance of the c4c national clinical trial networks for optimizing pediatric trial facilitation

Introduction:The high failure rate of industry-driven pediatric clinical trials leads to insufficient timely labeling of drugs in children and a lack of scientific evidence, resulting in the persistently high off-label drug use. National clinical trial networks can facilitate collaboration between sites, investigators, and experts, increasing the likelihood of successful trials. Within the conect4children (c4c) network, an Innovative Medicines Initiative 2-funded project, National Hubs hosted by National Clinical Trials Networks were set up across 21 European countries to facilitate the setup and execution of pediatric clinical trials. In this paper, we aim to present the performance metrics of the trial feasibility process as well as learnings and challenges encountered by the Belgian and Dutch Networks in working within the European c4c project.Method:The c4c National Hubs streamline pediatric clinical trials by initiating early country outreach, identifying overlapping studies, recommending quality trial sites, and supporting trial budgeting for both industry and academic settings. To show the impact of Pedmed-NL and Belgian Pediatric Clinical Research Network (BPCRN), internal metrics were collected from 2019 to 2022 on four industry-sponsored and three academic trials performed within the c4c network. Timelines and outcomes of the site identification were collected and analyzed for industry trials. A qualitative analysis was conducted through c4c platforms, sponsor interactions, and stakeholder engagement to evaluate the added value of a research network.Results:In industry-sponsored trials, full feasibility questionnaires were completed within 2 weeks (n = 48), and inclusion rates were up to 80% of clinical sites. Before committing to c4c, 14% of sites were contacted by industry, leading to communication burdens. Utilizing national infrastructure knowledge and therapeutic environment insights helped optimize trial timelines and address feasibility challenges. In addition, national adaptations, such as bilingual staff and site development, played a role in streamlining trial operations in both academic and industry settings. Performance and experiences were similar for both networks.Conclusion:The early-facilitation examples from the c4c trials demonstrated promising metrics for two National Hubs, including optimized start-up timelines and aiding site selection quality. The learnings and challenges of the Belgian and Dutch Networks provided insights for the development of clinical research networks

On the presence and functional significance of sympathetic premotor neurons with collateralized spinal axons in the rat

KEY POINTS: Spinally-projecting neurons of the rostral ventrolateral medulla (RVLM) determine sympathetic outflow to different territories of the body. Previous studies suggest the existence of RVLM neurons with distinct functional classes, such as neurons that target sympathetic nerves bound for functionally-similar tissue types (e.g. muscle vasculature). The existence of RVLM neurons with more general actions had not been critically tested. Using viral tracing, we show that a significant minority of RVLM neurons send axon collaterals to disparate spinal segments (T2 and T10 ). Furthermore, optogenetic activation of sympathetic premotor neurons projecting to lumbar spinal segments also produced activation of sympathetic nerves from rostral spinal segments that innervate functionally diverse tissues (heart and forelimb muscle). These findings suggest the existence of individual RVLM neurons for which the axons branch to drive sympathetic preganglionic neurons of more than one functional class and may be able to produce global changes in sympathetic activity. ABSTRACT: We investigate the extent of spinal axon collateralization of rat rostral ventrolateral medulla (RVLM) sympathetic premotor neurons and its functional consequences. In anatomical tracing experiments, two recombinant herpes viral vectors with retrograde tropism and expressing different fluorophores were injected into the intermediolateral column at upper thoracic and lower thoracic levels. Histological analysis revealed that ∼21% of RVLM bulbospinal neurons were retrogradely labelled by both vectors, indicating substantial axonal collateralization to disparate spinal segments. In functional experiments, another virus with retrograde tropism, a canine adenovirus expressing Cre recombinase, was injected into the left intermediolateral horn around the thoracolumbar junction, whereas a Cre-dependent viral vector encoding Channelrhodopsin2 under LoxP control was injected into the ipsilateral RVLM. In subsequent terminal experiments, blue laser light (473 nm × 20 ms pulses at 10 mW) was used to activate RVLM neurons that had been transduced by both vectors. Stimulus-locked activation, at appropriate latencies, was recorded in the following pairs of sympathetic nerves: forelimb and hindlimb muscle sympathetic fibres, as well as cardiac and either hindlimb muscle or lumbar sympathetic nerves. The latter result demonstrates that axon collaterals of lumbar-projecting RVLM neurons project to, and excite, both functionally similar (forelimb and hindlimb muscle) and functionally dissimilar (lumbar and cardiac) preganglionic neurons. Taken together, these findings show that the axons of a significant proportion of RVLM neurons collateralise widely within the spinal cord, and that they may excite preganglionic neurons of more than one functional class