Entropy production and time asymmetry in the presence of strong interactions

It is known that the equilibrium properties of open classical systems that are strongly coupled to a heat bath are described by a set of thermodynamic potentials related to the system's Hamiltonian of mean force. By adapting this framework to a more general class of nonequilibrium states, we show that the equilibrium properties of the bath can be well defined, even when the system is arbitrarily far from equilibrium and correlated with the bath. These states, which retain a notion of temperature, take the form of conditional equilibrium distributions. For out-of-equilibrium processes we show that the average entropy production quantifies the extent to which the system and bath state is driven away from the conditional equilibrium distribution. In addition, we show that the stochastic entropy production satisfies a generalized Crooks relation and can be used to quantify time asymmetry of correlated nonequilibrium processes. These results naturally extend the familiar properties of entropy production in weakly coupled systems to the strong coupling regime. Experimental measurements of the entropy production at strong coupling could be pursued using optomechanics or trapped-ion systems, which allow strong coupling to be engineered.

Association of RNA Biosignatures With Bacterial Infections in Febrile Infants Aged 60 Days or Younger

IMPORTANCE

Young febrile infants are at substantial risk of serious bacterial infections; however, the current culture-based diagnosis has limitations. Analysis of host expression patterns ("RNA biosignatures") in response to infections may provide an alternative diagnostic approach.

OBJECTIVE

To assess whether RNA biosignatures can distinguish febrile infants aged 60 days or younger with and without serious bacterial infections.

DESIGN, SETTING, AND PARTICIPANTS

Prospective observational study involving a convenience sample of febrile infants 60 days or younger evaluated for fever (temperature >38° C) in 22 emergency departments from December 2008 to December 2010 who underwent laboratory evaluations including blood cultures. A random sample of infants with and without bacterial infections was selected for RNA biosignature analysis. Afebrile healthy infants served as controls. Blood samples were collected for cultures and RNA biosignatures. Bioinformatics tools were applied to define RNA biosignatures to classify febrile infants by infection type.

EXPOSURE

RNA biosignatures compared with cultures for discriminating febrile infants with and without bacterial infections and infants with bacteremia from those without bacterial infections.

MAIN OUTCOMES AND MEASURES

Bacterial infection confirmed by culture. Performance of RNA biosignatures was compared with routine laboratory screening tests and Yale Observation Scale (YOS) scores.

RESULTS

Of 1883 febrile infants (median age, 37 days; 55.7% boys), RNA biosignatures were measured in 279 randomly selected infants (89 with bacterial infections-including 32 with bacteremia and 15 with urinary tract infections-and 190 without bacterial infections), and 19 afebrile healthy infants. Sixty-six classifier genes were identified that distinguished infants with and without bacterial infections in the test set with 87% (95% CI, 73%-95%) sensitivity and 89% (95% CI, 81%-93%) specificity. Ten classifier genes distinguished infants with bacteremia from those without bacterial infections in the test set with 94% (95% CI, 70%-100%) sensitivity and 95% (95% CI, 88%-98%) specificity. The incremental C statistic for the RNA biosignatures over the YOS score was 0.37 (95% CI, 0.30-0.43).

CONCLUSIONS AND RELEVANCE

In this preliminary study, RNA biosignatures were defined to distinguish febrile infants aged 60 days or younger with vs without bacterial infections. Further research with larger populations is needed to refine and validate the estimates of test accuracy and to assess the clinical utility of RNA biosignatures in practice.

Recruitment of Minority Adolescents and Young Adults into Randomised Clinical Trials: Testing the Design of the Technology Enhanced Community Health Nursing (TECH-N) Pelvic Inflammatory Disease Trial

PURPOSE

Pelvic inflammatory disease (PID) disproportionately affects adolescent and young adult (AYA) women and can negatively influence reproductive health trajectories. Few randomized controlled trials (RCTs) have focused on strategies to improve outpatient adherence or to reduce reproductive morbidity in this population. This paper describes the research methods and preliminary effectiveness of recruitment, retention, and intervention strategies employed in a novel RCT designed to test a technology-enhanced community-health nursing (TECH-N) intervention among urban AYA with PID.

METHODS

AYA women aged 13-25 years were recruited during acute PID visits in outpatient clinics and emergency departments (ED) to participate in this IRB-approved trial. Participants completed an audio-computerized self-interview (ACASI), provided vaginal specimens, and were randomized to standard treatment or the intervention. Intervention participants received text-messaging support for 30 days and a community health nurse (CHN) interventionist performed a home visit with clinical assessment within 5 days after enrollment. All patients received a full course of medications and completed research visits at 14-days (adherence), 30 days and 90 days with by an outreach worker. STI testing performed at the 30-and 90-day visits. Exploratory analyses using descriptive statistics were conducted to examine recruitment, retention, and follow-up data to test the overall design of the intervention.

RESULTS

In the first 48 months, 64% of 463 patients were eligible for the study and 81.2% of 293 eligible patients were recruited for the study (63.3%); 238 (81.2%) of eligible patients were enrolled. Most participants were African American (95.6%) with a mean age of 18.6 (2.3). Ninety-four percent of individuals assigned to the TECH-N intervention completed the nursing visits. All completed visits have been within the 5-day window and over 90% of patients in both arms have been retained over the 3-month follow-up period. Biological data suggests a shift in the biological milieu with the predominance of Chlamydia trachomatis, Mycoplasma genitalium, and Trichomonas vaginalis infections.

CONCLUSIONS

Preliminary data from the TECH-N study demonstrated that urban, low-income, minority AYA with PID can effectively be recruited and retained to participate in sexual and reproductive health RCTs with sufficient investment in the design and infrastructure of the study. Community-based sexual health interventions appear to be both feasible and acceptable in this population.

Long-term prediction of changes in health status, frailty, nursing care and mortality in community-dwelling senior citizens—results from the Longitudinal Urban Cohort Ageing Study (LUCAS)

Background

The detection of incipient functional decline in elderly persons is not an easy task. Here, we propose the self-reporting Functional Ability Index (FA index) suitable to screen functional competence in senior citizens in the community setting. Its prognostic validity was investigated in the Longitudinal Urban Cohort Ageing Study (LUCAS).

Methods

This index is based equally on both, resources and risks/functional restrictions which precede ADL limitations. Since 2001, the FA index was tested in the LUCAS cohort without any ADL restrictions at baseline (n = 1,679), and followed up by repeated questionnaires in Hamburg, Germany.

Results

Applying the index, 1,022 LUCAS participants were initially classified as Robust (60.9%), 220 as postRobust (13.1%), 172 as preFrail (10.2%) and 265 as Frail (15.8%). This classification correlated with self-reported health, chronic pain and depressive mood (rank correlations 0.42, 0.26, 0.21; all p < .0001). Survival analyses showed significant differences between these classes as determined by the FA index: the initially Robust survived longest, the Frail shortest (p < .0001). Analyses of the time to need of nursing care revealed similar results. Significant differences persisted after adjustment for age, sex and self-reported health.

Conclusions

Disability free lifetime and its development over time are important topics in public health. In this context, the FA index presented here provides answers to two questions. First, how to screen the heterogeneous population of community-dwelling senior citizens, i.e. for their functional ability/competence, and second, how far away they are from disability/dependency. Furthermore, the index provides a tool to address the urgent question whether incipient functional decline/incipient frailty can be recognized early to be influenced positively.

The FA index predicted change in functional status, future need of nursing care, and mortality in an unselected population of community-dwelling seniors. It implies an operational specification of the classification into Robust, postRobust, preFrail and Frail. Based on a self-administered questionnaire, the FA index allows easy screening of elderly persons for declining functional competence. Thereby, incipient functional decline is recognized, e.g. in GPs’ practices and senior community health centers, to initiate early appropriate preventive action.

Electronic supplementary material

The online version of this article (doi:10.1186/1471-2318-14-141) contains supplementary material, which is available to authorized users.

Nanoscale temperature measurements using non-equilibrium Brownian dynamics of a levitated nanosphere

Einstein realized that the fluctuations of a Brownian particle can be used to ascertain the properties of its environment. A large number of experiments have since exploited the Brownian motion of colloidal particles for studies of dissipative processes, providing insight into soft matter physics and leading to applications from energy harvesting to medical imaging. Here, we use heated optically levitated nanospheres to investigate the non-equilibrium properties of the gas surrounding them. Analysing the sphere's Brownian motion allows us to determine the temperature of the centre-of-mass motion of the sphere, its surface temperature and the heated gas temperature in two spatial dimensions. We observe asymmetric heating of the sphere and gas, with temperatures reaching the melting point of the material. This method offers opportunities for accurate temperature measurements with spatial resolution on the nanoscale, and provides a means for testing non-equilibrium thermodynamics.

Room temperature strong coupling between a microwave oscillator and an ensemble of electron spins

We demonstrate theoretically and experimentally the possibility to achieve the strong coupling regime at room temperature with a microwave electronic oscillator coupled with an ensemble of electron spins. The coupled system shows bistable behaviour, with a broad hysteresis and sharp transitions. The coupling strength and the hysteresis width can be adjusted through the number of spins in the ensemble, the temperature, and the microwave field strength.

[Resources and risks in old age: the LUCAS-I marker set for a classification of elderly people as fit, pre-frail and frail. First results on validity from the Longitudinal Urban Cohort Ageing Study (LUCAS), Hamburg]

BACKGROUND

There is a need for a simple self-administered instrument to assess frailty in community-dwelling seniors.

METHODS

We present a new marker set to assess the functional state of seniors. Contrary to current literature, we focus not only on risks, but also include resources. The questions relate to facts (ways to do things), rather than on subjective information (e.g. exhaustion). It was developed in the context of the Longitudinal Urban Cohort Ageing Study (LUCAS) in Hamburg, Germany.

RESULTS

The classification based on these questions proposes operational definitions of the terms fit, pre-frail and frail and is predictive for need for nursing care as well as mortality. A wealth of results establishes the validity of the categorisation compared to other health questions. One of the classification questions concerns cycling. For areas where cycling is not suitable, we propose to replace this question with one about independently walking 500 m. However, the cycling question appears to indicate frailty earlier.

CONCLUSION

The self-administered questionnaire provides a simple, cost-effective way to screen seniors for early signs of declining function in order to start preventive action.

The Longitudinal Urban Cohort Ageing Study (LUCAS): study protocol and participation in the first decade

Background

We present concept, study protocol and selected baseline data of the Longitudinal Urban Cohort Ageing Study (LUCAS) in Germany. LUCAS is a long-running cohort study of community-dwelling seniors complemented by specific studies of geriatric patients or diseases. Aims were to (1) Describe individual ageing trajectories in a metropolitan setting, documenting changes in functional status, the onset of frailty, disability and need of care; (2) Find determinants of healthy ageing; (3) Assess long-term effects of specific health promotion interventions; (4) Produce results for health care planning for fit, pre-frail, frail and disabled elderly persons; (5) Set up a framework for embedded studies to investigate various hypotheses in specific subgroups of elderly.

Methods/Design

In 2000, twenty-one general practitioners (GPs) were recruited in the Hamburg metropolitan area; they generated lists of all their patients 60 years and older. Persons not terminally ill, without daily need of assistance or professional care were eligible. Of these, n = 3,326 (48 %) agreed to participate and completed a small (baseline) and an extensive health questionnaire (wave 1). In 2007/2008, a re-recruitment took place including 2,012 participants: 743 men, 1,269 women (647 deaths, 197 losses, 470 declined further participation). In 2009/2010 n = 1,627 returned the questionnaire (90 deaths, 47 losses, 248 declined further participation) resulting in a good participation rate over ten years with limited and quantified dropouts. Presently, follow-up data from 2007/2008 (wave 2) and 2009/2010 (wave 3) are available. Data wave 4 is due in 2011/2012, and the project will be continued until 2013. Information on survival and need of nursing care was collected continuously and cross-checked against official records. We used Fisher’s exact test and t-tests. The study served repeatedly to evaluate health promotion interventions and concepts.

Discussion

LUCAS shows that a cohort study of older persons is feasible and can maintain a good participation rate over ten years, even when extensive self-reported health data are collected repeatedly through self-filled questionnaires. Evidently individual health developments of elderly persons can be tracked quantifying simultaneously behaviour, co-morbidity, functional competence and their changes. In future, we expect to generate results of significance about the five study aims listed above.

A qualitative assessment of factors that influence emergency medical services partnerships in prehospital research

OBJECTIVES

  Recent efforts to increase emergency medical services (EMS) prehospital research productivity by focusing on reducing systems-related barriers to research participation have had limited effect. The objective of this study was to explore the barriers and motivators to participating in research at the agency and provider levels and to solicit suggestions for improving the success of prehospital research projects.

METHODS

  The authors conducted a qualitative exploratory study of EMS personnel using focus group and focused interview methodology. EMS personnel affiliated with the Pediatric Emergency Care Applied Research Network (PECARN) hospitals were selected for participation using a purposive sampling plan. Exploratory questioning identified identified factors that influence participation in research and suggestions for ensuring successful research partnerships. Through iterative coding and analysis, the factors and suggestions that emerged from the data were organized into a behavioral change planning model.

RESULTS

  Fourteen focus groups were conducted, involving 88 EMS prehospital providers from 11 agencies. Thirty-five in-depth interviews with EMS administrators and researchers were also conducted. This sample was representative of prehospital personnel servicing the PECARN catchment area and was sufficient for analytical saturation. From the transcripts, the authors identified 17 barriers and 12 motivators to EMS personnel participation in research. Central to these data were patient safety, clarity of research purpose, benefits, liability, professionalism, research training, communication with the research team, reputation, administrators' support, and organizational culture. Interviewees also made 29 suggestions for increasing EMS personnel participation in research. During data analysis, the PRECEDE/PROCEED planning model was chosen for behavioral change to organize the data. Important to this model, factors and suggestions were mapped into those that predispose (knowledge, attitudes, and beliefs), reinforce (social support and norms), and/or enable (organizational) the participation in prehospital research.

CONCLUSIONS

  This study identified factors that influence the participation of EMS personnel in research and gathered suggestions for improvement. These findings were organized into the PRECEDE/PROCEED planning model that may help researchers successfully plan, implement, and complete prehospital research projects. The authors provide guidance to improve the research process including directly involving EMS providers throughout, a strong theme that emerged from the data. Future work is needed to determine the validity of this model and to assess if these findings are generalizable across prehospital settings other than those affiliated with PECARN.

[Rehabilitation instead of nursing care. Current state and future demand of geriatric rehabilitation]

In Germany, the term "rehabilitation instead of nursing care" represents an established legal claim and is also an imperative part within the general concept of comprehensive healthcare provision, reflecting the ongoing demographic and epidemiological developments. This report gives an overview on the rationale, the principles, and organizational conception of geriatric rehabilitation. This is completed by an assessment of existing structures for service provision and future demands of specific geriatric rehabilitation and geriatric care. There are well-established possibilities and facilities to realize the legal claim "rehabilitation instead of nursing care." However, these possibilities have to be further optimized in order to detect need earlier and to make adequate use of the potential resources in the growing number of old-aged persons.

Foot care education in patients with diabetes at low risk of complications: a consensus statement

AIMS

To define and agree a practical educational framework for delivery by all healthcare professionals managing patients with diabetes, particularly those at low risk of developing foot complications.

METHODS

A consensus meeting of a multidisciplinary expert panel. Prior to the meeting, relevant clinical papers were disseminated to the panel for review. The consensus was largely based upon the experts' clinical experience and judgement.

RESULTS

Four main health behaviours were identified for those at low risk of developing foot complications, namely: control of blood glucose levels; attendance at annual foot screening examination; reporting of any changes in foot health immediately; and the engagement in a simple daily foot care routine.

CONCLUSION

There is currently little evidence-based literature to support specific foot care practices. Patients with diabetes at low risk of developing complications should be encouraged to undertake a basic foot care regimen to reduce their likelihood of developing complications.

Pneumatic compression with foot pumps facilitates early postoperative mobilisation in total knee arthroplasty

Deep-vein thrombosis (DVT) and pulmonary embolism (PE) represent life-threatening postoperative complications frequently responsible for in-hospital mortality following total knee arthroplasty (TKA). Mechanical prophylaxis in the form of a foot pump offers an alternative to pharmacological and physical therapy. The aim of this prospective and randomised study was to examine the clinical efficacy of the A-V Impulse (AVI) system in reduction of soft-tissue swelling of the lower limb following a TKA. A total of 80 patients undergoing cemented TKA between September 2005 and December 2006 were randomised into two groups of 40 patients (n¹ = 40, n² = 40) during the 16-month study period. All patients received a subcutaneous dose of low molecular weight heparin (LMWH) (Enoxaparin/Clexane® 40 mg) once daily beginning 24 hours prior to the operation. The mean age for the groups n¹ and n² were 68.93 and 68.15 years, respectively. The reduction of soft-tissue swelling in the n¹ group was significantly higher (p < 0.05) compared with n². Evaluation of body mass index (BMI) with regard to the average reduction of soft-tissue swelling showed no significant influence (p < 0.05). The better function of the operated knee in group AVI was a significant predictor for improved agility and mobility (p < 0.01). No complications were reported for the application of the AVI. No ultrasonographic evidence of DVT or PE was found in any of the 80 patients during the investigative time period of eight days. After three months, there was no evidence of a symptomatic DVT.