Strain Measurement within an Intact Swine Periodontal Ligament.

The periodontal ligament (PDL) provides support, proprioception, nutrition, and protection within the tooth-PDL-bone complex (TPBC). While understanding the mechanical behavior of the PDL is critical, current research has inferred PDL mechanics from finite element models, from experimental measures on complete TPBCs, or through direct measurement of isolated PDL sections. Here, transducers are used in an attempt to quantify ex vivo PDL strain. In-fiber Bragg grating (FBG) sensors are small flexible sensors that can be placed within an intact TPBC and yield repeatable strain measurements from within the PDL space. The objective of this study was to determine: 1) if the FBG strain measured from the PDL space of intact swine premolars ex vivo was equivalent to physical PDL strains estimated through finite element analysis and 2) if a change in FBG strain could be linearly related to a change in finite element strain under variable tooth displacement, applied to an intact swine TPBC. Experimentally, individual TPBCs were subjected to 2 displacements (n = 14). The location of the FBG was determined from representative micro-computed tomography images. From a linear elastic finite element model of a TPBC, the strain magnitudes at the sensor locations were recorded. An experimental ratio (i.e., FBG strain at the first displacement divided by the FBG strain at the second displacement) and a finite element ratio (i.e., finite element strain at the first displacement divided by the finite element strain at the second displacement) were calculated. A linear regression model indicated a statistically significant relationship between the experimental and finite element ratio (P = 0.017) with a correlation coefficient (R2) of 0.448. It was concluded that the FBG sensor could be used as a measure for a change in strain and thus could be implemented in applications where the mechanical properties of an intact PDL are monitored over time.

Head Games: A Systematic Review and Meta-analysis Examining Concussion and Head Impact Incidence Rates, Modifiable Risk Factors, and Prevention Strategies in Youth Tackle Football.

OBJECTIVES: The aims were to (1) examine the rates and mechanisms of concussion and head impact in youth football (high school level or younger); (2) identify modifiable risk factors for concussion and head impact; and (3) evaluate the effectiveness of prevention strategies in tackle football at any level. METHODS: Nine databases (CINAHL Plus with Full Text; Cochrane Central Register of Controlled Trials; EMBASE; ERIC; Ovid MEDLINE(R) and Epub Ahead of Print, In-Process & Other Non-Indexed Citations and Daily; ProQuest Dissertations & Theses Global Database; PsycINFO; Scopus; and SPORTDiscus with Full Text) were searched using the search strategy focusing on four main concepts: concussion/head impact, tackle football, modifiable risk factors, and primary prevention. Two reviewers completed title, abstract, and full-text screening as well as risk of bias assessment (using the Downs and Black checklist), with a third author available to resolve any disagreements. MAIN RESULTS: After removing duplicates, 1911 articles were returned. Fifty-eight articles were included in the review and 20 in the meta-analysis. The overall combined rates of concussion (including game and practice-related concussion) based on the meta-analysis were 0.78 concussions/1000 athlete exposures [95% confidence interval (CI) 0.67-0.89] for high school football (ages 13-19) and 1.15 concussions/1000 athlete exposures (95% CI 0.89-1.41) for minor football players (ages 5-15). There is evidence that contact training and practice contact restrictions have reduced the rate of head impacts and concussion. Heads Up Football (an intervention focused on coach education and contact training) has been shown to reduce the rate of concussion by 32% and head impacts by 38% amongst high school football players. Limiting contact practices in high schools to 2 days per week reduced practice head impacts per player-season by 42%, and limiting full contact in practice to 75 min per week in the second week of the season and 60 min in week 3 and beyond resulted in a 54% decrease in the practice-related concussion rate (p = 0.003). CONCLUSIONS: This review identified a critical need for interventions to address the high rates of concussion and head impact in youth football. To date, contact training and contact restrictions have the strongest evidence supporting their effectiveness at reducing these rates. Future research should use consistent concussion definitions and validated injury surveillance systems, and ensure complete reporting of participant characteristics and sampling details. Prospero ID CRD42020193775.

Redox Flow Batteries, Hydrogen and Distributed Storage.

Social, economic, and political pressures are causing a shift in the global energy mix, with a preference toward renewable energy sources. In order to realize widespread implementation of these resources, large-scale storage of renewable energy is needed. Among the proposed energy storage technologies, redox flow batteries offer many unique advantages. The primary limitation of these systems, however, is their limited energy density which necessitates very large installations. In order to enhance the energy storage capacity of these systems, we have developed a unique dual-circuit architecture which enables two levels of energy storage; first in the conventional electrolyte, and then through the formation of hydrogen. Moreover, we have begun a pilot-scale demonstration project to investigate the scalability and technical readiness of this approach. This combination of conventional energy storage and hydrogen production is well aligned with the current trajectory of modern energy and mobility infrastructure. The combination of these two means of energy storage enables the possibility of an energy economy dominated by renewable resources.

Wavelength interrogation of fiber Bragg grating sensors using tapered hollow Bragg waveguides.

We describe an integrated system for wavelength interrogation, which uses tapered hollow Bragg waveguides coupled to an image sensor. Spectral shifts are extracted from the wavelength dependence of the light radiated at mode cutoff. Wavelength shifts as small as ~10 pm were resolved by employing a simple peak detection algorithm. Si/SiO2-based cladding mirrors enable a potential operational range of several hundred nanometers in the 1550 nm wavelength region for a taper length of ~1 mm. Interrogation of a strain-tuned grating was accomplished using a broadband amplified spontaneous emission (ASE) source, and potential for single-chip interrogation of multiplexed sensor arrays is demonstrated.

In situ distributed diagnostics of flowable electrode systems: resolving spatial and temporal limitations.

In this study, we have developed an in situ distributed diagnostics tool to investigate spatial and temporal effects in electrochemical systems based on flowable electrodes. Specifically, an experimental approach was developed that enables spatially-resolved voltage measurements to be obtained in situ, in real-time. To extract additional data from these distributed measurements, an experimentally-parameterized equivalent circuit model with a new 'flow capacitor' circuit element was developed to predict the distributions of various system parameters during operation. As a case study, this approach was applied to investigate the behavior of the suspension electrodes used in an electrochemical flow capacitor under flowing and static conditions. The volumetric capacitance is reduced from 15.6 F ml(-1) to 1.1 F ml(-1) under flowing conditions. Results indicate that the majority of the charging in suspension electrodes occurs within ∼750 µm of the current collectors during flow, which gives rise to significant state-of-charge gradients across the cell, as well as underutilization of the available active material. The underlying cause of this observation is attributed to the relatively high electrical resistance of the slurry coupled with a stratified charging regime and insufficient residence time. The observations highlight the need to develop more conductive slurries and to design cells with reduced charge transport lengths.

Post-traumatic stress disorder symptoms after acute lung injury: a 2-year prospective longitudinal study.

BACKGROUND: Survivors of critical illnesses often have clinically significant post-traumatic stress disorder (PTSD) symptoms. This study describes the 2-year prevalence and duration of PTSD symptoms after acute lung injury (ALI), and examines patient baseline and critical illness/intensive care-related risk factors. METHOD: This prospective, longitudinal cohort study recruited patients from 13 intensive care units (ICUs) in four hospitals, with follow-up 3, 6, 12 and 24 months after ALI onset. The outcome of interest was an Impact of Events Scale - Revised (IES-R) mean score ≥1.6 ('PTSD symptoms'). RESULTS: During the 2-year follow-up, 66/186 patients (35%) had PTSD symptoms, with the greatest prevalence by the 3-month follow-up. Fifty-six patients with post-ALI PTSD symptoms survived to the 24-month follow-up, and 35 (62%) of these had PTSD symptoms at the 24-month follow-up; 50% had taken psychiatric medications and 40% had seen a psychiatrist since hospital discharge. Risk/protective factors for PTSD symptoms were pre-ALI depression [hazard odds ratio (OR) 1.96, 95% confidence interval (CI) 1.06-3.64], ICU length of stay (for a doubling of days, OR 1.39, 95% CI 1.06-1.83), proportion of ICU days with sepsis (per decile, OR 1.08, 95% CI 1.00-1.16), high ICU opiate doses (mean morphine equivalent ≥100 mg/day, OR 2.13, 95% CI 1.02-4.42) and proportion of ICU days on opiates (per decile, OR 0.83, 95% CI 0.74-0.94) or corticosteroids (per decile, OR 0.91, 95% CI 0.84-0.99). CONCLUSIONS: PTSD symptoms are common, long-lasting and associated with psychiatric treatment during the first 2 years after ALI. Risk factors include pre-ALI depression, durations of stay and sepsis in the ICU, and administration of high-dose opiates in the ICU. Protective factors include durations of opiate and corticosteroid administration in the ICU.

Barriers to initiating insulin therapy in patients with type 2 diabetes mellitus in public-sector primary health care centres in Cape Town.

BACKGROUND: The majority of patients with type 2 diabetes mellitus in Cape Town who attend primary care community health centres (CHCs) have unsatisfactory glycaemic control. Insulin is rarely prescribed despite its being indicated for type 2 diabetic patients with inadequate metabolic control on maximum oral glucose-lowering agent (OGLA) therapy. OBJECTIVE: The study examined barriers to initiating insulin therapy in poorly controlled type 2 diabetes patients on maximum OGLAs in CHCs in the Cape Town metropolis. METHODS: Five focus group discussions and 10 in-depth semistructured individual interviews were conducted with 46 medical officers working at the CHCs. The discussions and interviews were transcribed and common themes were identified and categorised. RESULTS: Doctor, patient, and system barriers to initiating insulin therapy were identified. Doctors' barriers include lack of knowledge, lack of experience with and use of guidelines related to insulin therapy, language barriers between doctor and patients, and fear of hypoglycaemia. Patient barriers were mistaken beliefs about insulin, non-compliance, lack of understanding of diabetes, use of traditional herbs, fear of injections, and poor socioeconomic conditions. System barriers were inadequate time, lack of continuity of care and financial constraints. CONCLUSION: Suggestions for overcoming barriers include further education of doctors on insulin initiation and the use of standardised guidelines. In addition, a patient-centred approach with better communication between doctors and patients, which may be achieved by reorganising aspects of the health system, may improve patient knowledge, address mistaken beliefs, improve compliance and help overcome barriers. Further research is needed to investigate these recommendations and assess patients' and nurses' perceptions on initiating insulin therapy.

The contexts of adherence for African Americans with high blood pressure.

The contexts of adherence for African Americans with high blood pressure African American men between the ages of 18 and 49 years have the lowest rates of awareness, treatment and control of high blood pressure (HBP) of all age/race/gender groups in the United States. A qualitative study was done to gain an understanding of urban black males' experiences of living with HBP. In-depth semi-structured interviews were conducted with 19 black males. The interviews explored perceptions of health, health problems and priorities, and concerns of daily living that influenced appointment keeping and medication taking. The sample was a subset of 309 men participating in a 3-year clinical trial to improve HBP control in an inner city African-American population. Content analysis of transcribed interviews identified the following themes and related concerns: (a) personal contexts: meaning of health, high blood pressure and treatments; (b) social context: living as a young black male in an urban environment; and (c) cultural context of relating: patient-provider relationship can make a difference. Influencing participants' responses were: interpreting symptoms; adjusting medication taking; protecting personal privacy; allocating limited resources; dealing with addiction; and feeling cared for by a health care provider. Adherence appeared to be multifaceted and changing depending upon: the men's social, economic and personal circumstances; empathetic and non-judgemental assistance from providers; financial concerns and employment; and drug addiction. Findings are useful in refining high blood pressure interventions.

Relationship of alcohol and illicit drug use with high blood pressure care and control among urban hypertensive Black men.

OBJECTIVE: To examine the relationships among alcohol and illicit drug use and high blood pressure (HBP) care and control. DESIGN: Baseline cross-sectional data from an ongoing clinical trial evaluating the effectiveness of a HBP care program was utilized. METHODS: Data collected at baseline on 309 urban hypertensive Black men, aged 18-54, included: socio-demographics, health status, HBP care behaviors, alcohol and illicit drug use, urine screen for illicit drug use, and blood pressure (BP). RESULTS: Men using alcohol and illicit drugs were less likely to report having medical insurance, having a doctor for HBP care, engaging in critical patient behaviors for HBP control, being on HBP medications, and compliance with HBP medication regimen. Alcohol and illicit drug users were more likely to eat high fat/high salt foods and significantly more likely to smoke cigarettes. In comparison to abstainers, men who used both alcohol and illicit drugs were significantly more likely to have uncontrolled BP and higher systolic blood pressure (SBP). CONCLUSIONS: Alcohol and illicit drug use were negatively associated with HBP care behaviors. Thus, BP was poorly controlled in this group of alcohol and illicit drug users. Screening, counseling, and treatment for alcohol and illicit drug use should be essential components in comprehensive HBP care.

Barriers to hypertension care and control in young urban black men.

Barriers to high blood pressure (HBP) care and control have been reported in the literature for > 30 years. Few reports on barriers, however, have focused on the young black man with HBP, the age/sex/race group with the highest rates of early severe and complicated HBP and the lowest rates of awareness, treatment, and control. In a randomized clinical trial of comprehensive care for hypertensive young urban black men, factors potentially associated with care and control were assessed at baseline for the 309 enrolled men. A majority of the men encountered a variety of barriers including economic, social, and lifestyle obstacles to adequate BP care and control, including no current HBP care (49%), risk of alcoholism (62%), use of illicit drugs (45%), social isolation (47%), unemployment (40%), and lack of health insurance (51%). Having health insurance (odds ratio = 7.20, P = .00) and a negative urine drug screen (odds ratio = .56, P = .04) were significant predictors of being in HBP care. Low alcoholism risk and employment were identified as significant predictors of compliance with HBP medication-taking behavior. Men currently using illicit drugs were 2.64 times less likely to have controlled BP compared with their counterparts who did not use illicit drugs, and men currently taking HBP medication were 63 times more likely have controlled BP compared with men not taking HBP medication. Comprehensive interventions are needed to address socioeconomic and lifestyle issues as well as other barriers to care and treatment, if HBP care is to be salient and effective in this high risk group.