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This position statement is a consensus view of an expert committee convened by the European Society of Endodontology (ESE). The statement is based on current clinical and scientific evidence as well as the collective reflective practice of the committee. The aim is to provide clinicians with evidence‐based, authoritative information on the aetiology, clinical presentation, and management of cracks and fractures that typically manifest along the long axis of the crown and/or root.

Soft objects squeezing through small apertures are crucial for many in vivo and in vitro processes. Red blood cell transit time through splenic inter-endothelial slits (IESs) plays a crucial role in blood filtration and disease progression, while droplet velocity through constrictions in microfluidic devices is important for effective manipulation and separation processes. As these transit phenomena are not well understood, we sought to establish analytical and numerical solutions of viscous droplet transit through a rectangular slit. This study extends from our former theory of a circular pore because a rectangular slit is more realistic in many physiological and engineering applications. Here, we derived the ordinary differential equations (ODEs) of a droplet passing through a slit by combining planar Poiseuille flow, the Young-Laplace equations, and modifying them to consider the lubrication layer between the droplet and the slit wall. Compared to the pore case, we used the Roscoe solution instead of the Sampson one to account for the flow entering and exiting a rectangular slit. When the surface tension and lubrication layer were negligible, we derived the closed-form solutions of transit time. When the surface tension and lubrication layer were finite, the ODEs were solved numerically to study the impact of various parameters on the transit time. With our solutions, we identified the impact of prescribed pressure drop, slit dimensions, and droplet parameters such as surface tension, viscosity, and volume on transit time. In addition, we also considered the effect of pressure drop and surface tension near critical values. For this study, critical surface tension for a given pressure drop describes the threshold droplet surface tension that prevents transit, and critical pressure for a given surface tension describes the threshold pressure drop that prevents transit. Our solutions demonstrate that there is a linear relationship between pressure and the reciprocal of the transit time (referred to as inverse transit time), as well as a linear relationship between viscosity and transit time. Additionally, when the droplet size increases with respect to the slit dimensions, there is a corresponding increase in transit time. Most notably, we emphasize the initial antagonistic effect of surface tension which resists droplet passage but at the same time decreases the lubrication layer, thus facilitating passage. Our results provide quantitative calculations for understanding cells passing through slit-like constrictions and designing droplet microfluidic experiments.

Introduction: The associations between cumulative exposure to apolipoprotein B (apoB) containing lipoproteins across early adult life and incident ASCVD in later life have not been quantified. Methods: Of 4945 eligible Coronary Artery Risk Development in Young Adults (CARDIA) cohort participants we used NMR to measure apoB in 3110 participants who had samples available from the years 2, 7, 15, and 30 exams. To mitigate biases from missingness of data we conducted multiple imputation for apoB levels for the residual 1,835 participants without NMR measures of apoB. We estimated the participant-specific apoB throughout the exposure period (ages 19 to 40y) using nonparametric spline models. The area under the apoB/age curve was calculated as cumulative exposure and expressed in mg/dL*years. To quantify the association between cumulative apoB exposure during early life with incident ASCVD after age 40y we used demographic- and risk factor-adjusted* Cox regression models (see table). We used a restricted cubic spline to examine the pattern of association across the range of cumulative apoB exposure. Results: 4945 CARDIA participants were followed for a total of 88664 person*years; 255 incident ASCVD events occurred after age 40y. Participants with higher cumulative apoB levels were more likely to be men; and have higher BMI, BP, glucose, and tobacco use. In demographic and risk factor adjusted models a 100mg/dL*yr difference in cumulative apoB from ages 19 to 40y (representing a mean yearly difference of about +5mg/dL) was associated with HR 1.15 (95% CI:1.10-1.19) and HR 1.10 (95%CI:1.06-1.15) for ASCVD events, respectively. At apoB exposures >1700mg/dL*y (>80mg/dL/y) there was a strong, direct association with incident ASCVD after age 40y. Conclusion: Prevention strategies that reduce apoB exposures in early adult life will likely attenuate ASCVD risks later in life; targeting a usual apoB level < 80mg/dL may provide maximal benefit.

Perfluorooctane sulfonate (PFOS) belongs to a class of endocrine-disrupting chemicals, perfluoroalkyl chemicals (PFCs), implicated in adiposity. Although supposedly phased out since 2002, its use remains widespread in Asia. We aim to examine the relationship between exposure to PFOS and maternal hyperglycaemia and metabolic outcomes in the offspring. We measured blood PFOS and other PFCs in archived samples taken at 24-32weeks gestation from mothers in the Hong Kong centre of the Hyperglycaemia and Adverse Pregnancy Outcome (HAPO) study between 2002-2004. All mothers underwent 75g OGTT and GDM was diagnosed according to the IADPSG/WHO 2013 criteria. Pregnancy outcomes, neonatal anthropometrics and childhood outcomes at 7 years were documented. PFCs were measured using high performance LC-MS-MS. We completed analysis of PFCs in 1,601 maternal samples, a subset of 99 cord blood samples, and 970 offspring at 7 years follow-up. There is strong correlation among PFOS and other PFCs in cord blood (ρ=0.51-0.74, p<0.001), as well as correlation with maternal levels (ρ=0.60, p<0.001). Ratio of cord blood to maternal PFOS was 0.60. Using regression analysis with adjustment for maternal age, BMI, and offspring gender, maternal PFOS showed association with maternal 1 hour glucose, 2 hour glucose, HbA1c, AUC during OGTT and GDM, though only the association with HbA1c remained significant using log-transformed PFOS (beta 0.0746 ± 0.0132, p=1.7x10-8). Log-transformed maternal PFOS was associated with higher birthweight, lower birth length, higher ponderal index and lower neonatal sum of skin fold thickness (beta -0.337 ± 0.085, p=7.1x 10-5), after adjustment for all covariates. Maternal PFOS during pregnancy was associated with lower height in offspring at age 7, but not offspring glycaemic parameters. Exposure to PFOS may be an important contributing factor to the epidemic of hyperglycaemia in pregnancy and childhood metabolic disorders in Asia. Disclosure R.C.W. Ma: Research Support; Self; AstraZeneca, Bayer AG, Merck Sharp & Dohme Corp., Pfizer Inc.. Advisory Panel; Self; Boehringer Ingelheim GmbH, Nippon Boehringer Ingelheim Co. Ltd.. C.H.T. Tam: None. G. Cheung: None. W. Lowe: None. B.E. Metzger: None. W.H. Tam: None. C.K. Wong: None.

Even though this book has an unusual and alluringly engaging title that is somewhat ambiguous as well, it is a serious examination of the nature of landscapes and their meaning. It affirms that the...

ABSTRACTWhat do fiber optics, superconductors, memory wire, polymers, solid state devices, ferrofluid, rare earth magnets, carbon-based electroacoustic devices, and photonic crystals have in common? They are all products of materials science research. Many of these advances play an important role in improving daily life; all are capable of enhancing the teaching of physics. This paper will address how topics from materials science can be used to ignite student interest by providing the basis for exciting hands-on activities.

Scoring SAT-style exam essays, John S. O’Connor is struck by the disconnection between the subject matter and students’ personal lives. Further, O’Connor notes that such tests draw an alarming distinction between writing and “content”—as if the two are unrelated. O’Connor calls for a broader understanding of literacy, and he warns of dire consequences to students and to best practices in our classrooms if we rely on timed essay writing devoid of content as the best measure of student understanding.