Methods for estimating the case fatality ratio for a novel, emerging infectious disease.

During the course of an epidemic of a potentially fatal disease, it is important that the case fatality ratio be well estimated. The authors propose a novel method for doing so based on the Kaplan-Meier survival procedure, jointly considering two outcomes (death and recovery), and evaluate its performance by using data from the 2003 epidemic of severe acute respiratory syndrome in Hong Kong, People's Republic of China. They compare this estimate obtained at various points in the epidemic with the case fatality ratio eventually observed; with two commonly quoted, naïve estimates derived from cumulative incidence and mortality statistics at single time points; and with estimates in which a parametric mixture model is used. They demonstrate the importance of patient characteristics regarding outcome by analyzing subgroups defined by age at admission to the hospital

Investigating the impact of extraneous distractions on consultations in general practice: Lessons learned

<p>Abstract</p> <p>Background</p> <p>Extraneous distractions may influence the flow of general practice consultations. This study piloted a methodology to examine the impact of interrupting general practitioners (GPs) while consulting actor-patients.</p> <p>Methods</p> <p>Six GPs were video recorded consulting six actor-patients each presenting a different clinical scenario in a simulated surgery. Five cases presented red flag cancer symptoms. Half the consultations were interrupted. Two independent assessors, blinded to the occurrence of interruptions, assessed consultation performance using the Leicester Assessment Package (LAP) for clinical competence.</p> <p>Results</p> <p>24 of 36 consultations were video recorded with sufficient audio-visual clarity to allow scoring. The association between LAP score and three variables could be studied: a variety of interruptions, different GPs and various scenarios. Agreement between assessors on GP performance was poor and showed an increased bias with increasing LAP score. Despite this, the interruption did not significantly impact on assessor LAP scores (Mean difference: 0.22, P = 0.83) even after controlling for assessor, different GPs and scenarios.</p> <p>Conclusion</p> <p>Extraneous distractions had no impact on GP performance in this underpowered pilot study, a conclusion which needs to be confirmed in a larger study. However several important lessons were learned. Recorded actor-patient clinical sessions are logistically challenging. GPs whose skills were not previously assessed were working in unfamiliar surroundings dealing with relatively straight forward diagnostic challenges and may have anticipated the interruptions. In a redesign of this experiment it may be possible to eliminate some of these limitations.</p

Investigating the impact of extraneous distractions on consultations in general practice: Lessons learned

<p>Abstract</p> <p>Background</p> <p>Extraneous distractions may influence the flow of general practice consultations. This study piloted a methodology to examine the impact of interrupting general practitioners (GPs) while consulting actor-patients.</p> <p>Methods</p> <p>Six GPs were video recorded consulting six actor-patients each presenting a different clinical scenario in a simulated surgery. Five cases presented red flag cancer symptoms. Half the consultations were interrupted. Two independent assessors, blinded to the occurrence of interruptions, assessed consultation performance using the Leicester Assessment Package (LAP) for clinical competence.</p> <p>Results</p> <p>24 of 36 consultations were video recorded with sufficient audio-visual clarity to allow scoring. The association between LAP score and three variables could be studied: a variety of interruptions, different GPs and various scenarios. Agreement between assessors on GP performance was poor and showed an increased bias with increasing LAP score. Despite this, the interruption did not significantly impact on assessor LAP scores (Mean difference: 0.22, P = 0.83) even after controlling for assessor, different GPs and scenarios.</p> <p>Conclusion</p> <p>Extraneous distractions had no impact on GP performance in this underpowered pilot study, a conclusion which needs to be confirmed in a larger study. However several important lessons were learned. Recorded actor-patient clinical sessions are logistically challenging. GPs whose skills were not previously assessed were working in unfamiliar surroundings dealing with relatively straight forward diagnostic challenges and may have anticipated the interruptions. In a redesign of this experiment it may be possible to eliminate some of these limitations.</p

Effectiveness of student response systems in terms of learning environment, attitudes and achievement

In order to investigate the effectiveness of using Student Response Systems (SRS) among grade 7 and 8 science students in New York, the How Do You Feel About This Class? (HDYFATC) questionnaire was administered to 1097 students (532 students did use SRS and 565 students who did not use SRS). Data analyses attested to the sound factorial validity and internal consistency reliability of the HDYFATC, as well as its ability to differentiate between the perceptions of students in different classrooms. Very large differences between users and non-users of SRS, ranging from 1.17 to 2.45 standard deviations for various learning environment scales, attitudes and achievement, supported the efficacy of using SRS

A single sub-km Kuiper Belt object from a stellar Occultation in archival data

The Kuiper belt is a remnant of the primordial Solar System. Measurements of its size distribution constrain its accretion and collisional history, and the importance of material strength of Kuiper belt objects (KBOs). Small, sub-km sized, KBOs elude direct detection, but the signature of their occultations of background stars should be detectable. Observations at both optical and X-ray wavelengths claim to have detected such occultations, but their implied KBO abundances are inconsistent with each other and far exceed theoretical expectations. Here, we report an analysis of archival data that reveals an occultation by a body with a 500 m radius at a distance of 45 AU. The probability of this event to occur due to random statistical fluctuations within our data set is about 2%. Our survey yields a surface density of KBOs with radii larger than 250 m of 2.1^{+4.8}_{-1.7} x 10^7 deg^{-2}, ruling out inferred surface densities from previous claimed detections by more than 5 sigma. The fact that we detected only one event, firmly shows a deficit of sub-km sized KBOs compared to a population extrapolated from objects with r>50 km. This implies that sub-km sized KBOs are undergoing collisional erosion, just like debris disks observed around other stars.Comment: To appear in Nature on December 17, 2009. Under press embargo until 1800 hours London time on 16 December. 19 pages; 7 figure

Swarming populations of Salmonella represent a unique physiological state coupled to multiple mechanisms of antibiotic resistance

Salmonella enterica serovar Typhimurium is capable of swarming over semi-solid surfaces. Although its swarming behavior shares many readily observable similarities with other swarming bacteria, the phenomenon remains somewhat of an enigma in this bacterium since some attributes skew away from the better characterized systems. Swarming is quite distinct from the classic swimming motility, as there is a prerequisite for cells to first undergo a morphological transformation into swarmer cells. In some organisms, swarming is controlled by quorum sensing, and in others, swarming has been shown to be coupled to increased expression of important virulence factors. Swarming in serovar Typhimurium is coupled to elevated resistance to a wide variety of structurally and functionally distinct classes of antimicrobial compounds. As serovar Typhimurium differentiates into swarm cells, the pmrHFIJKLM operon is up-regulated, resulting in a more positively charged LPS core. Furthermore, as swarm cells begin to de-differentiate, the pmr operon expression is down-regulated, rapidly reaching the levels observed in swim cells. This is one potential mechanism which confers swarm cells increased resistance to antibiotics such as the cationic antimicrobial peptides. However, additional mechanisms are likely associated with the cells in the swarm state that confer elevated resistance to such a broad spectrum of antimicrobial agents

What do We Know About Entrepreneurial Finance and its Relationship with Growth?

This article explores what we do (and do not) know about entrepreneurial finance and its relationship with growth. Broadly, there is a need for research to go beyond traditional supply side/market failure issues to better understand the role of entrepreneurial cognition, objectives, ownership types and firm life-cycle stages in financing/investment decisions. We show that little is known about the pivotal relationship between access to external finance and growth due to limitations in current approaches to testing financial constraints. Instead, we propose that the relationship between funding gaps and business performance as a direct and nuanced approach to identifying financial constraints in different entrepreneurial finance markets requires scrutiny. There is also a necessity for research to disentangle cognitive from financial constraints and to better understand the role of financiers in enabling growth. In particular, there is a need to explore the relationship between non-bank sources of finance and growth, shorn of inherent survival and selection bias. We outline an agenda for future research to address gaps in our understanding

Avoidance behaviors and negative psychological responses in the general population in the initial stage of the H1N1 pandemic in Hong Kong

<p>Abstract</p> <p>Background</p> <p>During the SARS pandemic in Hong Kong, panic and worry were prevalent in the community and the general public avoided staying in public areas. Such avoidance behaviors could greatly impact daily routines of the community and the local economy. This study examined the prevalence of the avoidance behaviors (i.e. avoiding going out, visiting crowded places and visiting hospitals) and negative psychological responses of the general population in Hong Kong at the initial stage of the H1N1 epidemic.</p> <p>Methods</p> <p>A sample of 999 respondents was recruited in a population-based survey. Using random telephone numbers, respondents completed a structured questionnaire by telephone interviews at the 'pre-community spread phase' of the H1N1 epidemic in Hong Kong.</p> <p>Results</p> <p>This study found that 76.5% of the respondents currently avoided going out or visiting crowded places or hospitals, whilst 15% felt much worried about contracting H1N1 and 6% showed signs of emotional distress. Females, older respondents, those having unconfirmed beliefs about modes of transmissions, and those feeling worried and emotionally distressed due to H1N1 outbreak were more likely than others to adopt some avoidance behaviors. Those who perceived high severity and susceptibility of getting H1N1 and doubted the adequacy of governmental preparedness were more likely than others to feel emotionally distressed.</p> <p>Conclusions</p> <p>The prevalence of avoidance behaviors was very high. Cognitions, including unconfirmed beliefs about modes of transmission, perceived severity and susceptibility were associated with some of the avoidance behaviors and emotional distress variables. Public health education should therefore provide clear messages to rectify relevant perceptions.</p

Mass spectrometry imaging identifies palmitoylcarnitine as an immunological mediator during Salmonella Typhimurium infection

Salmonella Typhimurium causes a self-limiting gastroenteritis that may lead to systemic disease. Bacteria invade the small intestine, crossing the intestinal epithelium from where they are transported to the mesenteric lymph nodes (MLNs) within migrating immune cells. MLNs are an important site at which the innate and adaptive immune responses converge but their architecture and function is severely disrupted during S. Typhimurium infection. To further understand host-pathogen interactions at this site, we used mass spectrometry imaging (MSI) to analyse MLN tissue from a murine model of S. Typhimurium infection. A molecule, identified as palmitoylcarnitine (PalC), was of particular interest due to its high abundance at loci of S. Typhimurium infection and MLN disruption. High levels of PalC localised to sites within the MLNs where B and T cells were absent and where the perimeter of CD169+ sub capsular sinus macrophages was disrupted. MLN cells cultured ex vivo and treated with PalC had reduced CD4+CD25+ T cells and an increased number of B220+CD19+ B cells. The reduction in CD4+CD25+ T cells was likely due to apoptosis driven by increased caspase-3/7 activity. These data indicate that PalC significantly alters the host response in the MLNs, acting as a decisive factor in infection outcome