Beam Profiling of Dental Light Curing Units Using Different Camera-Based Systems

Objective This study aimed to perform the beam profile of dental light-curing units (LCUs) using mirrorless and smartphone cameras and correlate it to a camera-based laser beam profiling system. Materials and Methods Three LCUs were evaluated (Radii Plus; Bluephase G2; and VALO Cordless). The spectral power of the LCUs was measured by using a spectrophotometer. The light emitted from the LCUs was projected onto a glass diffuser, and the images were recorded by using a mirrorless camera (NEX-F3), a smartphone (iPhone) and a camera-based beam profiler. Bandpass optical-filters were used, and for each LCU, the total spectral power output was integrated to calibrate the images. Statistical analysis was performed by digital image correlation (pixel by pixel) using Pearson’s correlation (α = 0.05; β = 0.2). Results The beam profile images showed nonuniform radiant emittance and spectral emission distributions across all the LCUs light tip. A strong correlation was found among cameras (Pearson’s r = 0.91 ± 0.03 with 95% confidence interval [CI]: 0.88–0.94 for the NEX-F3 and Pearson’s r = 0.88 ± 0.04 with 95% CI: 0.84–0.92 for the iPhone). Conclusion The standard Ophir beam profile system presented the most accurate distribution, but the mirrorless and smartphone cameras presented a strong correlation in the irradiance distribution of the beam profile images. Alternative cameras can be used to perform light beam profile of dental LCUs, but caution is needed as the type of sensor, image bit depth, and image processing are important to obtain accurate results.

Mechanisms of Venoarteriolar Reflex in Type 2 Diabetes with or without Peripheral Neuropathy

The aim of this study is to investigate the underlying mechanisms of the venoarteriolar reflex (VAR) in type 2 diabetes mellitus (T2DM), with and without peripheral neuropathy. Laser Doppler flowmetry (LDF) recordings were performed on the medial malleus and dorsal foot skin, before and during leg dependency in healthy controls, in persons with obesity, in those with T2DM, in those with T2DM and subclinical neuropathy, and in those with T2DM and confirmed neuropathy. LDF recordings were analyzed with the wavelet transform to evaluate the mechanisms controlling the flowmotion (i.e., endothelial nitric oxide-independent and -dependent, neurogenic, myogenic, respiratory and cardiac mechanisms). Skin blood perfusion decreased throughout leg dependency at both sites. The decrease was blunted in persons with confirmed neuropathy compared to those with T2DM alone and the controls. During leg dependency, total spectral power increased in all groups compared to rest. The relative contribution of the endothelial bands increased and of the myogenic band decreased, without differences between groups. Neurogenic contribution decreased in controls, in persons with obesity and in those with T2DM, whereas it increased in subclinical- and confirmed neuropathy. In conclusion, this study provides evidence that confirmed diabetic neuropathy alters the VAR through the neurogenic response to leg dependency.

Theoretical Modeling and Analysis of the Contribution of the Near-Field Absorption to the Dipole Radiation Power in Top-Emitting Organic Light-Emitting Diodes

We theoretically model the near-field (NF) absorption for a multilayer micro-cavity (MMC) structure and investigate the contribution of the NF absorption to the dipole radiation power in top-emitting organic light-emitting diodes (OLEDs). The NF absorption occurs due to the interaction between an evanescent wave with a large in-plane wave vector and a planar metal layer in the vicinity of the dipole radiation. The analytical expressions of the NF absorption in the MMC structure are derived from the plane wave expansions of the electric field amplitude, which includes the two-beam and multi-beam interference terms. The transverse magnetic polarization light emitted by both horizontally and vertically oriented dipole emitters is considered in the NF absorption while the contribution of the transverse electric polarization light is neglected. Based on the total spectral power density calculated in a top-emitting OLED, the respective spectral response functions of surface plasmon (SP) modes and NF absorption are compared, where the summation of the Lorentzian line shape functions is used to represent spectral responses of SP modes. At large values of in-plane wave vectors, the spectral response caused by the NF absorption becomes significant and approaches the total spectral power density. In addition, the relative optical powers from various dipole dissipation mechanisms are calculated with respect to the dipole emitter position in the emission layer (EML), which shows the optical power coupled to the NF absorption is predominant over other mechanisms when the distance between the dipole emitter and the EML/Ag interface is less than 10 nm in the top-emitting OLED.

Muscle Activation Profile While Walking with Perturbations

To avoid falling consequential to unexpected balance loss i.e., perturbation, requires people to readjust their footing rapidly and effectively (i.e., recovery stepping response). We aimed to investigate lower limb muscle activation and differences between ankle and knee muscle recruitment due to unexpected support-surface perturbations during walking. This was measured by frequency content changes of surface electromyography (sEMG). Twenty adults (27.00±2.79 years, 10 females) were exposed to perturbations while walking on a treadmill in virtual reality environment. Perturbations were applied randomly in different phases of gait in 4 directions (i.e., anterior/posterior/right/left). sEMG signals from the tibialis anterior (TA) and vastus lateralis (VL) muscles were studied. sEMG total spectral power for all signal frequencies and for specific bands (40-150 Hz, 150-250 Hz, 250-400 Hz) were compared 4 seconds before perturbation (i.e., baseline) versus four seconds after perturbations. We found that compared to baseline there was a significant increase in the total spectral power of lower-extremity muscles at the first 3 seconds after perturbation, for all frequencies. TA had a significant differential change in frequency bands: 150-250Hz>40-150Hz, while VL demonstrated a different differential response in frequency bands 40-150Hz & 150-250Hz>250-400Hz. Both muscles showed an increase in total spectral power for the first second after perturbation followed by gradual decrease to baseline total spectral power subsiding after 3 seconds. Our findings suggest that muscle operating frequency is modulated in real time to fit functional goal requirements such as a rapid change of footing in response to unexpected loss of balance.New & NoteworthyTo study muscle spectral profiles in response to loss of balance, we investigated the dynamics of muscle spectral power changes, across different frequency bands after unannounced physical perturbations during walking. Our analysis showed increased activation of high-frequency motor units of the lower-limb muscles, subsiding 3 seconds after perturbation. Differential power increase of specific frequency bands suggests that muscle activation is modulated in real time to fit functional goal requirements.

Analysis of Autonomic Nervous System Functional Age and Heart Rate Variability in Mine Workers

Introduction: Heavy working conditions and many unpropitious factors influencing workers health participate in development of various health disorders, among other autonomic cardiovascular regulation malfunction. The aim of this study is to draw a comparison of autonomic nervous system functional age and heart rate variability changes between workers with and without mining occupational exposure. Material and methods: Short term HRV was measured by DiANS PF8 device in men with and without occupational mining exposure (exposure for 10 years at least) using standard orthoclinostathic protocol (each phase 300 sec or 300 heartbeats if heart rate under 60 bpm), excluding those with severe cardiovascular, metabolic, or psychiatric diseases, nicotine and other drugs abuse, as well as those, who underwent heavy stress situation during last year. Results: Evaluating 41 HRV records among miners (n=24, age 47.9 ± 6.1 years, exposure 22.5 ± 5 years) and non-miners (n=17, age 48.5 ± 6.9 years) we found significantly increased difference between functional age of ANS and calendar age in miners group (+7.2 ± 7.3 years) over against the non-miners group (−1.6 ± 6.5 years). No correlation was found between exposure duration and functional age of ANS difference. Analysis of HRV parameters show significant reduction in total spectral power, LF, HF and rMSSD in mine workers above 48 years of age. Discussion and conclusion: Our results show that influence of occupational work factors from mining exposure can clearly take part in worsening the reactivity of ANS, which can be associated with greater risk of developing mostly cardiovascular diseases. It is important to think of non-occupational factors improving or deteriorating ANS reactivity and of individual sensitivity to other external factors.

Effect of Losartan, an Angiotensin II Type 1 Receptor Antagonist on Cardiac Autonomic Functions of Rats During Acute and Chronic Inhibition of Nitric Oxide Synthesis

We studied the effect of losartan on baroreflex sensitivity (BRS) and heart rate variability (HRV) of adult Wistar rats during acute and chronic inhibition of nitric oxide synthesis by NG-nitro-L-arginine methyl ester (L-NAME). Chronic L-NAME administration (50 mg/kg per day for 7 days, orally through gavage) increased mean arterial pressure (MAP), heart rate but significantly decreased BRS. In addition, a significant fall of standard deviation of normal RR intervals, total spectral power, high frequency spectral power and a rise of low frequency to high frequency (LF: HF) ratio was seen. Acute L-NAME administration (30 mg/kg, i.v. bolus dose) also raised MAP and impaired HRV but it was associated with augmented BRS for bradycardia reflex. Losartan treatment (10 mg/kg, i.v.) in both acute and chronic L-NAME treated rats, decreased MAP but the difference was not significant. On the other hand, losartan administration normalized depressed BRS for bradycardia reflex and significantly reduced LF to HF ratio in chronic L-NAME treated rats. But this improvement was not observed in acute L-NAME group. These results indicate importance of mechanisms other than renin-angiotensin system in the pressor response of both acute as well as chronic L-NAME. However, autonomic dysregulation especially following chronic L-NAME appears to be partly angiotensin dependent.

Effects of insulin on the cardiac autonomic nervous system in insulin-resistant states

The effects of insulin infusion on cardiac autonomic nervous system (ANS) activity were investigated in healthy subjects (n = 15) and in patients with various types of insulin-resistance, such as obese subjects (n = 20) and those with hypertension (n = 15) or type II (non-insulin-dependent) diabetes (n = 22). Healthy subjects and patients underwent euglycaemic hyperinsulinaemic glucose clamp, and cardiac ANS and haemodynamic changes were investigated by continuous recording of heart rate variability by the Holter technique and by venous occlusion plethysmography respectively. At baseline, healthy subjects had the highest values for total spectral power and the low-frequency (LF) component, and the lowest value for the high-frequency (HF) component. In the pooled data (n = 72), the fasting plasma insulin concentration was correlated with baseline total spectral power (r = -0.37; P< 0.001) and the LF/HF ratio (r = -0.35; P< 0.003). Such correlations were still significant (P< 0.01 for both) after adjustment for body fat and mean arterial blood pressure. In a multivariate linear stepwise analysis (n = 72), a model including body fat, waist/hip ratio, fasting plasma glucose concentration and insulin-mediated glucose uptake explained 47% of the variability of the change in the LF/HF ratio, with body fat (t = -3.11; P< 0.01) and insulin-mediated glucose uptake (t = -3.48; P< 0.008) being significantly and independently associated with insulin-mediated changes in the LF/HF ratio. Insulin infusion reduced the total spectral power and increased the LF/HF ratio in healthy subjects, but not in insulin-resistant patients. In conclusion, our study demonstrates that insulin fails to stimulate cardiac ANS activity in insulin-resistant patients, independently of the causes of insulin resistance.

Changes in Electroencephalogram and Autonomic Cardiovascular Activity during Induction of Anesthesia with Sevoflurane Compared with Halothane in Children

Background This study was design to assess clinical agitation, electroencephalogram (EEG) and autonomic cardiovascular activity changes in children during induction of anesthesia with sevoflurane compared with halothane using noninvasive recording of EEG, heart rate, and finger blood pressure. Methods Children aged 2-12 yr premedicated with midazolam were randomly assigned to one of three induction techniques: 7% sevoflurane in 100% O2 (group SevoRAPID); 2%, 4%, 6%, and 7% sevoflurane in 100% O2 (group SevoINCR); or 1%, 2%, 3%, and 3.5% halothane in 50% N2O-50% O2 (group HaloN2O). An additional group of children who received 7% sevoflurane in 50% N2O-50% O2 (group SevoN2O) was enrolled after completion of the study. Induction was videotaped. EEG, heart rate, and finger blood pressure were continuously recorded during induction until 5 min after tracheal intubation and analyzed in frequency domain using spectral analysis. Results Agitation was more frequent when anesthesia was induced with 100% O2 compared to the mixture of oxygen and nitrous oxide. No seizures were recorded in any group. In the four groups, induction of anesthesia was associated with an increase in EEG total spectral power and a shift toward the low-frequency bands. Sharp slow waves were present on EEG tracings of the three sevoflurane groups, whereas slow waves and fast rhythms (spindles) were observed in the halothane group. Sevoflurane induced a greater withdrawal of parasympathetic activity than halothane and a transient relative increase in sympathetic vascular tone at loss of eyelash reflex. Conclusions Agitation observed during sevoflurane induction was not associated with seizures. Sevoflurane induction induced a marked inhibition of parasympathetic control of heart rate.