Loop Quantum Gravity

The problem of finding the quantum theory of the gravitational field, and thus understanding what is quantum spacetime, is still open. One of the most active of the current approaches is loop quantum gravity. Loop quantum gravity is a mathematically well-defined, non-perturbative and background independent quantization of general relativity, with its conventional matter couplings. The research in loop quantum gravity forms today a vast area, ranging from mathematical foundations to physical applications. Among the most significative results obtained are: (i) The computation of the physical spectra of geometrical quantities such as area and volume; which yields quantitative predictions on Planck-scale physics. (ii) A derivation of the Bekenstein-Hawking black hole entropy formula. (iii) An intriguing physical picture of the microstructure of quantum physical space, characterized by a polymer-like Planck scale discreteness. This discreteness emerges naturally from the quantum theory and provides a mathematically well-defined realization of Wheeler's intuition of a spacetime ``foam''. Long standing open problems within the approach (lack of a scalar product, overcompleteness of the loop basis, implementation of reality conditions) have been fully solved. The weak part of the approach is the treatment of the dynamics: at present there exist several proposals, which are intensely debated. Here, I provide a general overview of ideas, techniques, results and open problems of this candidate theory of quantum gravity, and a guide to the relevant literature.Comment: Review paper written for the electronic journal `Living Reviews'. 34 page

Experiences With and Attitudes Toward Death and Dying Among Homeless Persons

BACKGROUND: Homeless persons face many barriers to health care, have few resources, and experience high death rates. They live lives of disenfranchisement and neglect. Few studies have explored their experiences and attitudes toward death and dying. Unfortunately, studies done in other populations may not apply to homeless persons. Exploring these experiences and attitudes may provide insight into life, health care, and end-of-life (EOL) concerns of this population. OBJECTIVE: To explore the experiences and attitudes toward death and dying among homeless persons. DESIGN: Qualitative study utilizing focus groups. PARTICIPANTS: Fifty-three homeless persons recruited from homeless service agencies. MEASUREMENTS: In-depth interviews, which were audiotaped and transcribed. RESULTS: We present seven themes, some of which are previously unreported. Homeless persons described many significant experiences with death and dying, and many participants suffered losses while very young. These encounters influenced participants’ attitudes toward risks and risky behavior: e.g., for some, these experiences provided justification for high-risk behaviors and influenced their behaviors while living on the streets. For others, they may be associated with their homelessness. Finally, these experiences informed their attitudes toward death and dying as well as EOL care; homeless persons believe that care will be poor at the EOL. CONCLUSIONS: Findings from this study have implications for addressing social services, health promotion, prevention, and EOL care for homeless persons, as well as for others who are poor and disenfranchised

Evidence and Policy in Aid-Dependent Settings

This chapter examines how the political dynamics of aid relationships can affect the use of evidence within health policymaking. Empirical examples from Cambodia, Ethiopia and Ghana illustrate how relationships between national governments and donor agencies influence the ways in which evidence is generated, selected, or utilised to inform policymaking. We particularly consider how relationships with donors influence the underlying systems and processes of evidence use. We find a number of issues affecting which bodies or forms of evidence are taken to be policy relevant, including: levels of local technical capacity to utilise or synthesise evidence; differing stakeholder framing of issues; and the influence of non-state actors on sector-wide systems of agenda setting. The chapter also reflects on some of the key governance implications of these arrangements in which global actors promote forms of evidence use – often under a banner of technical efficiency – with limited consideration for local representation or accountability

Autoimmune and autoinflammatory mechanisms in uveitis

The eye, as currently viewed, is neither immunologically ignorant nor sequestered from the systemic environment. The eye utilises distinct immunoregulatory mechanisms to preserve tissue and cellular function in the face of immune-mediated insult; clinically, inflammation following such an insult is termed uveitis. The intra-ocular inflammation in uveitis may be clinically obvious as a result of infection (e.g. toxoplasma, herpes), but in the main infection, if any, remains covert. We now recognise that healthy tissues including the retina have regulatory mechanisms imparted by control of myeloid cells through receptors (e.g. CD200R) and soluble inhibitory factors (e.g. alpha-MSH), regulation of the blood retinal barrier, and active immune surveillance. Once homoeostasis has been disrupted and inflammation ensues, the mechanisms to regulate inflammation, including T cell apoptosis, generation of Treg cells, and myeloid cell suppression in situ, are less successful. Why inflammation becomes persistent remains unknown, but extrapolating from animal models, possibilities include differential trafficking of T cells from the retina, residency of CD8(+) T cells, and alterations of myeloid cell phenotype and function. Translating lessons learned from animal models to humans has been helped by system biology approaches and informatics, which suggest that diseased animals and people share similar changes in T cell phenotypes and monocyte function to date. Together the data infer a possible cryptic infectious drive in uveitis that unlocks and drives persistent autoimmune responses, or promotes further innate immune responses. Thus there may be many mechanisms in common with those observed in autoinflammatory disorders

Mock juror perceptions of child witnesses on the autism spectrum: the impact of providing diagnostic labels and information about autism

Research suggests that autistic children can provide accurate and forensically useful eyewitness evidence. However, members of a jury also rely on non-verbal behaviours when judging the credibility of a witness, and this could determine the verdict of a case. We presented mock jurors with videos (from an experimental study) of one of two child witnesses on the autism spectrum being interviewed about a mock minor crime. Results demonstrated that providing jurors with generic information about autism and/or informing them of the child’s diagnostic label differentially affected credibility ratings, but not for both children. Implications for how to present information about child witnesses with autism to a jury – highlighting the need for approaches tailored to individual children – are discussed

Peer navigation improves diagnostic follow-up after breast cancer screening among Korean American women: results of a randomized trial

To test an intervention to increase adherence to diagnostic follow-up tests among Asian American women. Korean American women who were referred for a diagnostic follow-up test (mainly diagnostic mammograms) and who had missed their follow-up appointment were eligible to participate in the study. Women from two clinics (n = 176) were randomly allocated to a usual care control arm or a peer navigator intervention arm. A 20-min telephone survey was administered to women in both study arms six months after they were identified to assess demographic and socio-economic characteristics and the primary outcome, self-reported completion of the recommended follow-up exam. Among women who completed the survey at six-month follow-up, self-reported completion of follow-up procedures was 97% in the intervention arm and 67% in the control arm (p < 0.001). Based on an intent-to-treat analysis of all women who were randomized and an assumption of no completion of follow-up exam for women with missing outcome data, self-reported completion of follow-up was 61% in the intervention arm and 46% in the usual care control arm (p < 0.069). Our results suggest that a peer navigator intervention to assist Korean American women to obtain follow-up diagnostic tests after an abnormal breast cancer screening test is efficacious

Mechanisms of leukocyte migration across the blood–retina barrier

Immune-mediated inflammation in the retina is regulated by a combination of anatomical, physiological and immuno-regulatory mechanisms, referred to as the blood–retina barrier (BRB). The BRB is thought to be part of the specialised ocular microenvironment that confers protection or “immune privilege” by deviating or suppressing destructive inflammation. The barrier between the blood circulation and the retina is maintained at two separate anatomical sites. These are the endothelial cells of the inner retinal vasculature and the retinal pigment epithelial cells on Bruch’s membrane between the fenestrated choroidal vessels and the outer retina. The structure and regulation of the tight junctions forming the physical barrier are described. For leukocyte migration across the BRB to occur, changes are needed in both the leukocytes themselves and the cells forming the barrier. We review how the blood–retina barrier is compromised in various inflammatory diseases and discuss the mechanisms controlling leukocyte subset migration into the retina in uveoretinitis in more detail. In particular, we examine the relative roles of selectins and integrins in leukocyte interactions with the vascular endothelium and the pivotal role of chemokines in selective recruitment of leukocyte subsets, triggering adhesion, diapedesis and migration of inflammatory cells into the retinal tissue

A proof of principle for using adaptive testing in routine Outcome Monitoring: the efficiency of the Mood and Anxiety Symptoms Questionnaire -Anhedonic Depression CAT

<p>Abstract</p> <p>Background</p> <p>In Routine Outcome Monitoring (ROM) there is a high demand for short assessments. Computerized Adaptive Testing (CAT) is a promising method for efficient assessment. In this article, the efficiency of a CAT version of the Mood and Anxiety Symptom Questionnaire, - Anhedonic Depression scale (MASQ-AD) for use in ROM was scrutinized in a simulation study.</p> <p>Methods</p> <p>The responses of a large sample of patients (<it>N </it>= 3,597) obtained through ROM were used. The psychometric evaluation showed that the items met the requirements for CAT. In the simulations, CATs with several measurement precision requirements were run on the item responses as if they had been collected adaptively.</p> <p>Results</p> <p>CATs employing only a small number of items gave results which, both in terms of depression measurement and criterion validity, were only marginally different from the results of a full MASQ-AD assessment.</p> <p>Conclusions</p> <p>It was concluded that CAT improved the efficiency of the MASQ-AD questionnaire very much. The strengths and limitations of the application of CAT in ROM are discussed.</p

A Cross-Sectional Study of Barriers to Personal Health Record Use among Patients Attending a Safety-Net Clinic

BACKGROUND: Personal health records (PHR) may improve patients' health by providing access to and context for health information. Among patients receiving care at a safety-net HIV/AIDS clinic, we examined the hypothesis that a mental health (MH) or substance use (SU) condition represents a barrier to engagement with web-based health information, as measured by consent to participate in a trial that provided access to personal (PHR) or general (non-PHR) health information portals and by completion of baseline study surveys posted there. METHODS: Participants were individually trained to access and navigate individualized online accounts and to complete study surveys. In response to need, during accrual months 4 to 12 we enhanced participant training to encourage survey completion with the help of staff. Using logistic regression models, we estimated odds ratios for study participation and for survey completion by combined MH/SU status, adjusted for levels of computer competency, on-study training, and demographics. RESULTS: Among 2,871 clinic patients, 70% had MH/SU conditions, with depression (38%) and methamphetamine use (17%) most commonly documented. Middle-aged patients and those with a MH/SU condition were over-represented among study participants (N = 338). Survey completion was statistically independent of MH/SU status (OR, 1.85 [95% CI, 0.93-3.66]) but tended to be higher among those with MH/SU conditions. Completion rates were low among beginner computer users, regardless of training level (<50%), but adequate among advanced users (>70%). CONCLUSIONS: Among patients attending a safety-net clinic, MH/SU conditions were not barriers to engagement with web-based health information. Instead, level of computer competency was useful for identifying individuals requiring substantial computer training in order to fully participate in the study. Intensive on-study training was insufficient to enable beginner computer users to complete study surveys