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This paper is complementary to a recent work [Kumar et al., Rev. Sci. Instrum. 54, 463 (1983)] that described a simple, inexpensive technique for correcting laser-induced, pulsed signals for fluctuations of the individual laser excitation pulses. This inexpensive pulse-by-pulse correction technique, based on analog circuitry, exhibits an improved time-constant characteristic and is applicable to both linear and nonlinear processes. Circuit details are presented here and the versatility of the technique is illustrated by laser optogalvanic spectroscopy of the iodine molecule. [ABSTRACT FROM AUTHOR]

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Components of primary (azurophilic) granules of polymorphonuclear leukocytes (PMNs) have been implicated as important mediators in pulpal inflammation. This anatomical study used ultracryoimmunocytochemical techniques and characterized and contrasted the subcellular distributions of human PMN elastase (PMN-E), PMN cathepsin-G (PMN-CG), and alpha-2 macroglobulin (α-2M) in healthy and inflamed dental pulps. Inflamed pulpal tissue sections revealed an intense distribution of PMN-E in the extracellular domain throughout the collagen matrix. PMN-E was also localized in the perinuclear cytoplasm of PMNs and distributed in a random fashion. PMN-CG was localized intensely in the intracellular granules of PMNs and observed moderately within the extracellular matrix. Healthy pulpal tissues exposed to PMN-E and PMN-CG antibodies revealed no evidence of PMN infiltration and no specific labeling. α-2M, a natural serum inhibitor of PMN-E and PMN-CG, was distributed in an intense fashion within the intravascular compartments of both inflamed and healthy pulpal samples. Immunogold-labeling for α-2M was observed in moderate amounts within the extravascular domain of inflamed pulpal samples but only in mild amounts within the same area of healthy tissues. These results suggest that PMN-E and PMN-CG are released to the extracellular matrix of irreversibly inflamed teeth, enabling them to facilitate pulpal connective tissue destruction. Conversely, moderate extravascular labeling for α-2M within inflamed samples suggests a physiological attempt at inhibiting the pulpal connective tissue destruction mediated by human PMN-E and PMN-CG. [ABSTRACT FROM AUTHOR]

Electrocardiogram (ECG) is a non-invasive method to monitor electric activities inside the heart. The signals observed on the surface of human body have very low amplitude, and thus, ECG is highly vulnerable to noise. One of the most devastating noise is power line interference (PLI) and its harmonics, which are interlaced with ECG signal even if the ECG equipment is operated on battery. The problem is further complicated when the frequency of PLI is not static, making the conventional notch filter completely ineffective. High-resolution electrocardiogram (HRECG) is a specialized technique in which higher frequency components present in the ECG signal are observed; here, we need to eliminate the harmonics of PLI as well. In this paper, we propose an intelligent adaptive noise rejection filter, which tracks and eliminates PLI as well as its harmonics. The proposed system can estimate the frequency of PLI and tune the adaptive filter for precise elimination of PLI as well as its harmonics without the requirement of an auxiliary reference input. The proposed system is based on recursive state space model, inherited with less computational complexity and performs well in a non-stationary environment. The proposed system responds well to the ongoing variations in amplitude and frequency of PLI present in the HRECG signal as well as intracardiac signal. The proposed system does not require any reference signal for tracking the PLI and its harmonics, and it is capable to self-adjust its tracking frequency for highly precise filtration of first, third, and fifth harmonics of PLI.

Mammary ductal ectasia (MDE) with bloody nipple discharge (BND) appears to be exceptionally rare and presents a challenge for management to the consulting physician. We report A 5-month-old boy presented with a 3 weeks history of unilateral breast enlargement associated with intermittent spontaneous bloody nipple discharge. Ultrasound evaluation showed a 1.0 cm × 0.57 cm cystic mass in the right subareolar region with dilated ducts. Cytological evaluation of nipple discharge showed no malignant cells. The breast swelling and nipple discharge resolved spontaneously after 1 months without recurrence during the following 7 months. We conclude that mammary ductal ectasia is a benign and self-limited disorder in infancy and can be manged conservatively without any specific treatment to avoid unnecessary invasive surgical intervention.

The nonlinear Klein-Gordon equation (KGE) models many nonlinear phenomena. In this paper, we propose a scheme for numerical approximation of solutions of the one-dimensional nonlinear KGE. A common approach to find a solution of a nonlinear system is to first linearize the equations by successive substitution or the Newton iteration method and then solve a linear least squares problem. Here, we show that it can be advantageous to form a sum of squared residuals of the nonlinear problem and then find a zero of the gradient. Our scheme is based on the Sobolev gradient method for solving a nonlinear least square problem directly. The numerical results are compared with Lattice Boltzmann Method (LBM). The L2, L∞, and Root-Mean-Square (RMS) values indicate better accuracy of the proposed method with less computational effort.

Critical points related to the singular perturbed reaction diffusion models are calculated using weighted Sobolev gradient method in finite element setting. Performance of different Sobolev gradients has been discussed for varying diffusion coefficient values. A comparison is shown between the weighted and unweighted Sobolev gradients in two and three dimensions. The superiority of the method is also demonstrated by showing comparison with Newton's method.

Background/Objectives : Osteoporosis and periodontal disease (PD) are associated with significant morbidity and mortality especially among post-menopausal women. The attributable causes of mortality include bone fragility, hip fractures, surgical risks, complications associated with immobility/disability, and mental health issues. This cross-sectional study aims to investigate the association between oral health and bone diseases along with the factors that predict this association. Methods : This study included post-menopausal women undergoing routine bone density evaluation. Following informed consent, case histories were collected using an investigator-administered questionnaire. The oral cavity was inspected for the health of the oral structures and periodontium. Bone density data, interpreted by a radiologist, were also collected. Data were analyzed using chi-square and logistic regression tests with the significance level set at 5%. Results : Among 100 eligible participants, mean age and body mass index (BMI) were 68.17 ± 8.33 years and 29.59 ± 6.13 kg/m 2 , respectively. A total of 23 participants (23.0%) had T2DM, 29 (29.0%) had < 20 natural teeth, and 17 (17.0%) had normal bone mineral density. Except for age (aOR 1.171, p < 0.001), BMI (aOR 0.763, p < 0.001), and past osteoporotic fractures (aOR 21.273, p = 0.021), all other factors were insignificant predictors of bone loss. Conclusions : Although the unadjusted results suggest a relationship between oral health indicators and bone loss, these relationships were not present when other factors were included in an adjusted model. Our findings suggest PD by itself may not be a risk factor for bone loss but that the two conditions may have similar risk factors.

The COVID-19 pandemic has increased negative emotions and decreased positive emotions globally. Left unchecked, these emotional changes might have a wide array of adverse impacts. To reduce negative emotions and increase positive emotions, we tested the effectiveness of reappraisal, an emotion-regulation strategy that modifies how one thinks about a situation. Participants from 87 countries and regions (n = 21,644) were randomly assigned to one of two brief reappraisal interventions (reconstrual or repurposing) or one of two control conditions (active or passive). Results revealed that both reappraisal interventions (vesus both control conditions) consistently reduced negative emotions and increased positive emotions across different measures. Reconstrual and repurposing interventions had similar effects. Importantly, planned exploratory analyses indicated that reappraisal interventions did not reduce intentions to practice preventive health behaviours. The findings demonstrate the viability of creating scalable, low-cost interventions for use around the world. PROTOCOL REGISTRATION: The stage 1 protocol for this Registered Report was accepted in principle on 12 May 2020. The protocol, as accepted by the journal, can be found at https://doi.org/10.6084/m9.figshare.c.4878591.v1., (© 2021. The Author(s), under exclusive licence to Springer Nature Limited.)

Introduction: Undergraduate medical education has evolved necessarily with the increasing utilization of technology and the availability of ancillary resources developed for medical students. However, medical educational resources are expensive and there have been few studies validating these resources for their ability to significantly modify student exam performance., Methods: A post-exam survey was devised to evaluate medical students for resource usage, student-perceived preparedness, and exam performance., Results: Students who felt more prepared for exams performed better than students who felt less prepared ( p  = .017). Students who watched didactic lectures online and those who utilized peer-to-peer tutoring outperformed students who did not use these resources ( p  = .035, p  = .008). Analyses of the data show that none of the purchased resources utilized significantly improved student exam performance. The majority of students used between six and eight resources for exam preparation. There may be a slightly negative association with the quantity of resources used and exam scores ( p  = .18)., Discussion: Contrary to traditional confidence studies that correlate overconfidence with underperformance, medical students who reported feeling more prepared for exams performed better than students who felt less prepared., Conclusion: Medical students may have a more complete grasp of their knowledge base and deficits, which may enable a more accurate match between exam expectations and academic performance. This post-exam survey method can be customized and applied to evaluate resource utility as it pertains to specific undergraduate medical education curricula at individual institutions., Competing Interests: Competing InterestsThe authors declare no competing interests., (© The Author(s) 2021.)

Introduction: Twitter is growing in popularity and influence among emergency physicians (EP), with over 2200 self-identified EP users. As Twitter's popularity has increased among EPs so too has its influence. While there has been debate about the value of Twitter as an effective educational delivery tool, little attention has been paid to the nature of the conversation occurring on Twitter. We aim to describe how influential EPs use Twitter by characterizing the language, purpose, frequencies, content, and degree of engagement of their tweets., Methods: We performed a mixed-methods analysis following a combined content analysis approach. We conducted qualitative and quantitative analyses of a sample of tweets from the 61 most influential EPs on Twitter. We present descriptive tweet characteristics and noteworthy themes., Results: We analyzed 1375 unique tweets from 57 unique users, representing 93% of the influential Twitter EPs. A majority of tweets (1104/1375, 80%) elicited some response in the form of retweets, likes, or replies, demonstrating community engagement. The qualitative analysis identified 15 distinct categories of tweets., Conclusion: Influential EPs on Twitter were engaged in largely medical conversations in which most messages generated some form of interaction. They shared resources and opinions while also building social rapport in a community of practice. This data can help EPs make informed decisions about social media engagement.

Transdermal drug delivery is impeded by the natural barrier of epidermis namely stratum corneum. This limits the route to transport of drugs with a log octanol-water partition coefficient of 1 to 3, molecular weight of less than 500 Da and melting point of less than 200°C. Nanotechnology has received widespread investigation as nanocarriers are deemed to be able to fluidize the stratum corneum as a function of size, shape, surface charges, and hydrophilicity-hydrophobicity balance, while delivering drugs across the skin barrier. This review provides an overview and update on the latest designs of liposomes, ethosomes, transfersomes, niosomes, magnetosomes, oilin- water nanoemulsions, water-in-oil nanoemulsions, bicontinuous nanoemulsions, covalently crosslinked polysaccharide nanoparticles, ionically crosslinked polysaccharide nanoparticles, polyelectrolyte coacervated nanoparticles and hydrophobically modified polysaccharide nanoparticles with respect to their ability to fuse or fluidize lipid/protein/tight junction regimes of skin, and effect changes in skin permeability and drug flux. Universal relationships of nanocarrier size, zeta potential and chemical composition on transdermal permeation characteristics of drugs will be developed and discussed.

This study describes the histologic characteristics of root surfaces of primary teeth from children with prepubertal periodontitis (PP). Fifteen primary teeth from 4 children with PP, and 2 control primary teeth from 2 healthy children were examined. Light microscopy revealed normal root surfaces in the control teeth. In contrast, the PP specimens revealed bacteria inside dentin tubules or covering cementum, a cuticle, or resorbed dentin; normal, wider than normal, or hypoplastic cementum; resorption lacunae with various depths; aplastic root resorption; alternate resorption and repair; and active repair. No cementoclasts were found in the resorption lacunae. Scanning electron microscopy revealed intrabony and suprabony root areas, and a "plaque free zone" (PFZ). Colonies of filaments were evident at the cemento-enamel junction (CEJ). The suprabony root surfaces had resorption lacunae, isolated short rods, calculus, colonies of filaments, or colonies composed by an heterogeneous bacterial population. The coronal boundary of the PFZ was the border of a sheet-like structure, which included isolated rods or filaments. At the PFZ, isolated filaments and rods, and a fibril matrix were evident. The apical boundary of the PFZ consisted of bundles of soft tissue remnants or the insertion of the periodontal fibers. The intrabony surfaces were mostly covered by soft tissue, which included isolated filaments and short rods. Resorption lacunae with or without soft tissue were also evident in this area. Crystals of calcium oxalate dihydrate and erythrocytes in distinct forms were found at various root areas. The present findings are different from those previously reported for hypophosphatasia specimens.

Tropical ulcer is a disabling condition of the lower leg affecting mainly young adults and older children. Microscopic observations of lesion material have shown fusiform bacilli and spirochetes. We used anaerobic culture techniques to isolate and identify these fusiform bacilli. Electron microscopic (EM) studies were performed to characterize the spirochetes. Material collected on swabs was used to inoculate pre-reduced media and to prepare smears for gram staining; the swabs were placed in fixative for EM study. After incubation, colonies containing fusiform bacilli were subcultured. The anaerobic gram-negative fusiform isolates were identified as Fusobacterium nucleatum using biochemical reactions, hemagglutination testing, and reaction of antigen preparations of the isolates and ATCC strains in serological tests with rabbit antisera. EM observations of negatively stained spirochetes revealed an 8-16-8 periplasmic flagellar arrangement. F. nucleatum and spirochetes may participate in the pathogenesis of this polymicrobic infection.

Scanning electron microscopy was employed to observe the physical interactions between Cristispira spp. and the crystalline style of the Chesapeake Bay oyster (Crassostrea virginica Gmelin 1791). Cristispira organisms were found associated with both the inner and outer layers of the posterior two-thirds of the style. The spirochetes possessed blunt-tipped ends, a cell diameter range of 0.6 to 0.8 mum, and distended spirochetal envelopes which followed the contour of the cells. Transmission electron microscopy showed that the distension of the envelope was probably due to the containment of numerous axial filaments. In addition, they were found to possess two distinct spiral shapes which were dependent on whether their location was inside or on the surface of the style.

Patients with juvenile periodontitis (JP) were grouped into one of the two recognized forms of the disease: a localized form affecting incisors and first molars (LJP) and a generalized form affecting more than 14 teeth (GJP). The role of the neutrophil in the etiology and pathogenesis of LJP has recently been recognized. Experiments aimed at confirming previous information related to neutrophil chemotaxis defects in LJP were performed. Additional experiments aimed at demonstrating significant differences in phagocytosis of bacterial spores and inducing spore germination were also completed. Age- and sex-matched healthy subjects were used as "internal" controls (experiments run concomitantly). Peripheral blood neutrophils from 29 LJP, 24 GJP and 24 healthy subjects were assessed for chemotaxis. This assay was performed in a Boyden diffusion chamber using 10(-8) M N-formylmethionylleucylphenylalanine as chemoattractant. A chemotactic defect was defined being 2 standard deviations below the mean of healthy subjects. Twenty-three of 29 LJP (79%) and 14 of 25 GJP (58%) had a neutrophil defect. Peripheral blood neutrophil phagocytosis assays were performed in vitro using radiolabeled bacterial spores [45Ca]Bacillus cereus. Eighteen of 29 LJP (62%) and 7 of 24 GJP (29%) had a phagocytic defect. Neutrophil-induced spore germination assessed in vitro showed that 13 of 20 LJP (65%) and 3 of 8 GJP (38%) had this defect. These observations indicate that patients with JP have abnormalities in neutrophil functions of chemotaxis, phagocytosis and spore germination.