Dead Time Compensation for High-Flux Ranging

Dead time effects have been considered a major limitation for fast data acquisition in various time-correlated single photon counting applications, since a commonly adopted approach for dead time mitigation is to operate in the low-flux regime where dead time effects can be ignored. Through the application of lidar ranging, this work explores the empirical distribution of detection times in the presence of dead time and demonstrates that an accurate statistical model can result in reduced ranging error with shorter data acquisition time when operating in the high-flux regime. Specifically, we show that the empirical distribution of detection times converges to the stationary distribution of a Markov chain. Depth estimation can then be performed by passing the empirical distribution through a filter matched to the stationary distribution. Moreover, based on the Markov chain model, we formulate the recovery of arrival distribution from detection distribution as a nonlinear inverse problem and solve it via provably convergent mathematical optimization. By comparing per-detection Fisher information for depth estimation from high- and low-flux detection time distributions, we provide an analytical basis for possible improvement of ranging performance resulting from the presence of dead time. Finally, we demonstrate the effectiveness of our formulation and algorithm via simulations of lidar ranging.Comment: Revision with added estimation results, references, and figures, and modified appendice

Isoscalar dipole mode in relativistic random phase approximation

The isoscalar giant dipole resonance structure in $^{208}$Pb is calculated in the framework of a fully consistent relativistic random phase approximation, based on effective mean-field Lagrangians with nonlinear meson self-interaction terms. The results are compared with recent experimental data and with calculations performed in the Hartree-Fock plus RPA framework. Two basic isoscalar dipole modes are identified from the analysis of the velocity distributions. The discrepancy between the calculated strength distributions and current experimental data is discussed, as well as the implications for the determination of the nuclear matter incompressibility.Comment: 9 pages, Latex, 3. p.s figs, submitted to Phys. Lett.

Recruiting and Retaining Individuals with Serious Mental Illness and Diabetes in Clinical Research: Lessons Learned from a Randomized, Controlled Trial.

Abstract: Recruitment and retention of individuals with serious mental illness (SMI) and comorbid diabetes mellitus (DM) in research studies can be challenging with major impediments being difficulties reaching participants via telephone contact, logistic difficulties due to lack of transportation, ongoing psychiatric symptoms, and significant medical complications. Research staff directly involved in recruitment and retention processes of this study reviewed their experiences. The largest barriers at the macro, mediator, and micro levels identified in this study were inclement weather, transportation difficulties, and intermittent and inaccessible telephone contact. Barrier work-around practices included using the health system’s EHR to obtain current phone numbers, providing transportation assistance (bus passes or parking reimbursement), and flexible scheduling of appointments. Suggestions are intended to assist in planning for recruitment and retention strategies

Glucose hypometabolism in the Auditory Pathway in Age Related Hearing Loss in the ADNI cohort

Purpose: Hearing loss (HL) is one of the most common age-related diseases. Here, we investigate the central auditory correlates of HL in people with normal cognition and mild cognitive impairment (MCI) and test their association with genetic markers with the aim of revealing pathogenic mechanisms. / Methods: Brain glucose metabolism based on FDG-PET, self-reported HL status, and genetic data were obtained from the Alzheimer’s Disease Neuroimaging Initiative (ADNI) cohort. FDG-PET data was analysed from 742 control subjects (non-HL with normal cognition or MCI) and 162 cases (HL with normal cognition or MCI) with age ranges of 72.2 ± 7.1 and 77.4 ± 6.4, respectively. Voxel-wise statistics of FDG uptake differences between cases and controls were computed using the generalised linear model in SPM12. An additional 1515 FDG-PET scans of 618 participants were analysed using linear mixed effect models to assess longitudinal HL effects. Furthermore, a quantitative trait genome-wide association study (GWAS) was conducted on the glucose uptake within regions of interest (ROIs), which were defined by the voxel-wise comparison, using genotyping data with 5,082,878 variants available for HL cases and HL controls (N = 817). / Results: The HL group exhibited hypometabolism in the bilateral Heschl’s gyrus (kleft = 323; kright = 151; Tleft = 4.55; Tright = 4.14; peak Puncorr < 0.001), the inferior colliculus (k = 219;T = 3.53; peak Puncorr < 0.001) and cochlear nucleus (k = 18;T = 3.55; peak Puncorr < 0.001) after age correction and using a cluster forming height threshold P < 0.005 (FWE-uncorrected). Moreover, in an age-matched subset, the cluster comprising the left Heschl’s gyrus survived the FWE-correction (kleft = 1903; Tleft = 4.39; cluster PFWE-corr = 0.001). The quantitative trait GWAS identified no genome-wide significant locus in the three HL ROIs. However, various loci were associated at the suggestive threshold (p < 1e-05). / Conclusion: Compared to the non-HL group, glucose metabolism in the HL group was lower in the auditory cortex, the inferior colliculus, and the cochlear nucleus although the effect sizes were small. The GWAS identified candidate genes that might influence FDG uptake in these regions. However, the specific biological pathway(s) underlying the role of these genes in FDG-hypometabolism in the auditory pathway requires further investigation

Nursing churn and turnover in Australian hospitals: Nurses perceptions and suggestions for supportive strategies

Background: This study aimed to reveal nurses' experiences and perceptions of turnover in Australian hospitals and identify strategies to improve retention, performance and job satisfaction. Nursing turnover is a serious issue that can compromise patient safety, increase health care costs and impact on staff morale. A qualitative design was used to analyze responses from 362 nurses collected from a national survey of nurses from medical and surgical nursing units across 3 Australian States/Territories.Method: A qualitative design was used to analyze responses from 362 nurses collected from a national survey of nurses from medical and surgical nursing units across 3 Australian States/Territories.Results: Key factors affecting nursing turnover were limited career opportunities; poor support; a lack of recognition; and negative staff attitudes. The nursing working environment is characterised by inappropriate skill-mix and inadequate patient-staff ratios; a lack of overseas qualified nurses with appropriate skills; low involvement in decision-making processes; and increased patient demands. These issues impacted upon heavy workloads and stress levels with nurses feeling undervalued and disempowered. Nurses described supportive strategies: improving performance appraisals, responsive preceptorship and flexible employment options.Conclusion: Nursing turnover is influenced by the experiences of nurses. Positive steps can be made towards improving workplace conditions and ensuring nurse retention. Improving performance management and work design are strategies that nurse managers could harness to reduce turnover. © 2014 Dawson et al.; licensee BioMed Central Ltd

CMTM6 maintains the expression of PD-L1 and regulates anti-tumour immunity

Cancer cells exploit the expression of the programmed death-1 (PD-1) ligand 1 (PD-L1) to subvert T-cell-mediated immunosurveillance. The success of therapies that disrupt PD-L1-mediated tumour tolerance has highlighted the need to understand the molecular regulation of PD-L1 expression1. Here we identify the uncharacterized protein CMTM6 as a critical regulator of PD-L1 in a broad range of cancer cells, by using a genome-wide CRISPR–Cas9 screen. CMTM6 is a ubiquitously expressed protein that binds PD-L1 and maintains its cell surface expression. CMTM6 is not required for PD-L1 maturation but co-localizes with PD-L1 at the plasma membrane and in recycling endosomes, where it prevents PD-L1 from being targeted for lysosome-mediated degradation. Using a quantitative approach to profile the entire plasma membrane proteome, we find that CMTM6 displays specificity for PD-L1. Notably, CMTM6 depletion decreases PD-L1 without compromising cell surface expression of MHC class I. CMTM6 depletion, via the reduction of PD-L1, significantly alleviates the suppression of tumour-specific T cell activity in vitro and in vivo. These findings provide insights into the biology of PD-L1 regulation, identify a previously unrecognized master regulator of this critical immune checkpoint and highlight a potential therapeutic target to overcome immune evasion by tumour cells.M.L.B. is supported by a Cancer Research UK Clinician Scientist Fellowship (C53779/A20097), Addenbrooke’s Charitable Trust award and NIHR fellowship. P.J.L. is supported by a Wellcome Trust PRF (101835/Z/13/Z) and work in the Lehner laboratory is supported by NHSBT, NIHR Cambridge BRC, a Wellcome Trust Strategic Award to CIMR, and the Addenbrooke’s Charitable Trust M.A.D. is supported by a Senior Leukaemia Foundation Australia Fellowship and work in the Dawson laboratory is supported by the NHMRC (Grants 1085015, 1106444 and 1106447) Cancer Council Victoria and Leukaemia Foundation Australia. Cancer Research UK (C53779/A20097

Rho-Nucleon Tensor Coupling and Charge-Exchange Resonances

The Gamow-Teller resonances are discussed in the context of a self-consistent RPA, based on the relativistic mean field theory. We inquire on the possibility of substituting the phenomenological Landau-Migdal force by a microscopic nucleon-nucleon interaction generated from the rho-nucleon tensor coupling. The effect of this coupling turns out to be very small when the short range correlations are not taken into account, but too large when these correlations are simulated by the simple extraction of the contact terms from the resulting nucleon-nucleon interaction.Comment: 15 pages, LaTeX, 2 figures; extended text, improved figures, new references added, the version appearing in Phys.Lett.

Knowledge management and team innovation: understanding the team processes underlying high innovativeness

Being innovative means being willing ‘to go the extra mile’ beyond routine tasks in teams. It also means that team members are willing to consider different perspectives in heterogeneous teams and to share information. Important antecedents of team innovation are successful information sharing and helping behaviour among team members. Although the importance of information sharing for innovation is seemingly self-evident, we still know very little about the group processes that support team innovation (West, 2002). Information sharing is a group process that is an indispensable part of team integration. Team roles and team tasks need to be discussed to successfully achieve team goals. In heterogeneous teams with members from different occupational backgrounds integrating processes such as information sharing are even more important. To date, research on information sharing has focused mainly on the type of information that is shared or unshared (Brodbeck, Kerschreiter, Mojzisch, Frey, & Schulz-Hardt, 2002; Stasser, Stewart, & Wittenbaum, 1995) and on antecedents of information sharing, such as trust (Butler, 1999), task and reward interdependence (Moser & Wodzicki, 2007), or how person perception might affect information exchange (de Bruin & Van Lange, 2000). The link between output measures of group performance, such as innovativeness, and information sharing has always been implied and has been explored theoretically to some extent (Diehl & Ziegler, 2000), but empirical studies that go beyond organisational case studies (Basadur & Gelade, 2006) are still scarce. If we define innovation as the introduction of new ideas and new ways of doing things at work as suggested by West (2002), then sharing information about these new ideas and developing ideas further in the team through information sharing is a prerequisite for team innovation. However, the role of information is likely to be very different for routine team tasks and for team innovation. Especially in heterogeneous teams with members from different occupational backgrounds, task interdependence is likely to be lower for new and innovative processes than for established procedures and routine tasks. This means that information sharing is ‘nice to have’ and would be expected to affect team innovation, but is at the same time not indispensable for completing routine team tasks. This distinction is important, because under low task interdependence different social processes come into play in groups (Moser & Wodzicki, 2007). Information sharing under low task interdependence can be defined as a form of prosocial behaviour at work. It means that team members are willing to put in an extra effort and ‘go the extra mile’ to discuss their perspectives on the team task with colleagues from a different disciplinary background. In the studies presented here we argue that the importance of information sharing and helping behaviour for team innovation should therefore increase if occupational diversity is high and team size is large. The hypothesis was tested in two independent samples of health care teams (N1=72 breast cancer care teams, N2=113 community mental health teams), using team innovation rated by independent experts as outcome variable. Multiple regression analysis showed that helping behaviour had a significant independent effect on innovation for both team types, while information sharing only had a significant association with innovation for breast cancer teams. The interaction effects of team size and occupational diversity were tested with moderated regression analysis for both helping behaviour and information sharing. Both team processes showed strong main effects, which were even stronger if occupational diversity was high. There was also a main effect of team size on innovation, which is increased especially if helping behaviour in the team is strong. The interaction effect with team size could thus be confirmed for both teams, while the interaction with team size was only found for the mental health care teams. The partially different results for the two different team types could be explained by the differences in task and team structures. While mental health teams have stable membership and meet less regularly than breast cancer teams, breast cancer teams are cross-functional teams with multiple team memberships. In conclusion, it can be said that especially helping behaviour seems to be crucial for team innovation. If teams are large, and helping behaviour among team members is strong, the capacity for innovation seems to be greatly increased. Implications for understanding the psychological processes underlying team innovation and for managing knowledge sharing in teams are discussed

Harnessing Demographic Differences in Organizations: What Moderates the Effects of Workplace Diversity?

To account for the double-edged nature of demographic workplace diversity (i.e. relational demography, work group diversity, and organizational diversity) effects on social integration, performance and well-being related variables, research has moved away from simple main effect approaches and started examining variables that moderate these effects. While there is no shortage of primary studies of the conditions under which diversity leads to positive or negative outcomes, it remains unclear which contingency factors make it work. Using the Categorization-Elaboration Model (van Knippenberg, DeDreu, & Homan 2004) as our theoretical lens we review variables moderating the effects of workplace diversity on social integration, performance and well-being outcomes, focusing on factors that organizations and managers have control over (i.e. strategy, unit design, HR, leadership, climate/culture, and individual differences). We point out avenues for future research and conclude with practical implications

Collective multipole excitations in a microscopic relativistic approach

A relativistic mean field description of collective excitations of atomic nuclei is studied in the framework of a fully self-consistent relativistic random phase approximation (RRPA). In particular, results of RRPA calculations of multipole giant resonances and of low-lying collective states in spherical nuclei are analyzed. By using effective Lagrangians which, in the mean-field approximation, provide an accurate description of ground-state properties, an excellent agreement with experimental data is also found for the excitation energies of low-lying collective states and of giant resonances. Two points are essential for the successful application of the RRPA in the description of dynamical properties of finite nuclei: (i) the use of effective Lagrangians with non-linear terms in the meson sector, and (ii) the fully consistent treatment of the Dirac sea of negative energy states.Comment: 10 figures, submitted to Nucl.Phys.