The behavior of standing waves near the end of an open pipe with low mean flow.

The acoustic standing wave near the end of an open pipe is investigated using spectrally analyzed high-speed transmission electronic speckle pattern interferometry. It is shown that the standing wave extends beyond the open end of the pipe and the amplitude decays exponentially with distance from the end. Additionally, a pressure node is observed near the end of the pipe in a position that is not spatially periodic with the other nodes in the standing wave. A sinusoidal fit to the amplitude of the standing wave inside the pipe indicates that the end correction is well predicted by current theory.

Imaging acoustic standing waves in the presence of flowing gas.

A method for imaging an acoustic standing wave in the presence of flowing gas is described. The optical power at the acoustic frequency in each pixel of a series of high-speed transmission electronic speckle pattern interferograms is used to map the steady-state pressure variations of an acoustic standing wave. The utility of the process is demonstrated by imaging the standing wave inside a transparent organ pipe.

Visualization of exhaled breath by transmission electronic speckle pattern interferometry.

A method for visualizing the air flow from the mouths of vocalists and wind musical instruments is presented. The method is based on a modification of electronic speckle pattern interferometry that incorporates the interference of a transmitted object beam rather than the standard method using a reflected object beam. The resulting whole-field real-time images are a valuable resource for both scientific and pedagogical use.

Do "brassy" sounding musical instruments need increased safe distancing requirements to minimize the spread of COVID-19?

Brass wind instruments with long sections of cylindrical pipe, such as trumpets and trombones, sound "brassy" when played at a fortissimo level due to the generation of a shock front in the instrument. It has been suggested that these shock fronts may increase the spread of COVID-19 by propelling respiratory particles containing the SARS-CoV-2 virus several meters due to particle entrainment in the low pressure area behind the shocks. To determine the likelihood of this occurring, fluorescent particles, ranging in size from 10-50 µm, were dropped into the shock regions produced by a trombone, a trumpet, and a shock tube. Preliminary results indicate that propagation of small airborne particles by the shock fronts radiating from brass wind instruments is unlikely.

Treating hyperglycemia in early pregnancy: a randomized controlled trial.

BACKGROUND: Treating women with gestational diabetes mellitus in the third trimester improves perinatal outcomes. It is unknown whether treating women with mild glucose intolerance earlier in pregnancy would be beneficial in the reduction of maternal and neonatal morbidities. OBJECTIVE: In women with hyperglycemia (hemoglobin A1c ≥5.7% and/or fasting glucose ≥92 mg/dL) in early pregnancy, we sought to determine whether immediate treatment improved maternal and neonatal outcomes. STUDY DESIGN: This unblinded randomized controlled trial enrolled women with hyperglycemia at ≤15+0 weeks gestation between 2013 and 2015. Participants were assigned randomly to early pregnancy or third-trimester treatment of hyperglycemia that included nutrition counseling, glucose monitoring, and medications as needed. Participants underwent a blinded 2-hour glucose tolerance test at 24-28 weeks gestation. Exclusion criteria were pregestational diabetes mellitus and multiple gestations. The primary outcome was the proportion of infants with neonatal umbilical cord C-peptide >1.77 nmoL (90th percentile). Secondary outcomes were neonatal fat mass, infant World Health Organization weight-for-length percentile at birth, maternal gestational weight gain, and diagnosis of gestational diabetes mellitus on glucose tolerance test. Mann-Whitney-Wilcoxon test and Fisher's exact test were used, as appropriate. RESULTS: A total of 202 women were assigned randomly; 45 women dropped out before delivery, which left cases 157 for analysis (82 with early pregnancy and 75 with third-trimester treatment). The trial was terminated early because of low enrollment. Baseline characteristics were similar between groups. There was no difference in C-peptide >90th percentile between groups (1 [1.5%] vs 4 [6.7%]; P=.19) in the early pregnancy and third-trimester groups, respectively). There was also no difference in fat mass (0.37±0.16 vs 0.36±0.17 kg; P=.91), weight-for-length percentile at birth (25% vs 25%; P=.46), or macrosomia (1.5 vs 5.0%; P=.84). Maternal gestational weight gain was 22.6±12.9 lb and 23.9±11.2 lb in the early pregnancy and third-trimester groups, respectively (P=.88). Gestational diabetes mellitus was diagnosed in 19.0% of the cohort and did not differ between groups (14.2% vs 25.8%; P=.17). CONCLUSION: In this population of women with hyperglycemia, treatment in early pregnancy did not appear to improve maternal or neonatal outcomes significantly. Given comparable results in both groups, caution should be used in the initiation of an intensive diabetes mellitus treatment protocol for women with the diagnosis of hyperglycemia in early gestation.

Novel mutation in CCBE 1 as a cause of recurrent hydrops fetalis from Hennekam lymphangiectasia-lymphedema syndrome-1.

Whole exome sequencing (WES) was used to determine the etiology of recurrent hydrops fetalis in this case of Hennekam lymphangiectasia-lymphedema syndrome-1. WES is a useful approach for diagnosing rare single-gene conditions with nonspecific phenotypes and should be considered early in the diagnostic process of investigating fetal abnormalities.

Structural contributions to phantom partial generation in the piano.

The results of experiments designed to determine the origin of the anomalous frequency components in the sound of the piano commonly referred to as phantom partials are reported. It is shown that these overtones, which occur at the sum and difference frequencies associated with the transverse string motion, are produced by nonlinearities in both the string and the wooden components of the piano. However, the contribution from the string is significantly smaller than the contributions from other components.

Folic acid supplement use and the risk of gestational hypertension and preeclampsia.

BACKGROUND: Hypertensive disorders of pregnancy are among the leading causes of maternal morbidity and mortality. Studies suggest that the use of folic acid may lower the risk of hypertensive disorders in pregnant women. AIM: The aim of this study was to assess the effects of timing and duration of folic acid-containing supplement use on the risk for gestational hypertension and preeclampsia. METHODS: Exposures and outcomes data were obtained through interviews and review of participant's medical records from the MotherToBaby cohort studies across the United States and Canada. Demographics, medical history, lifestyle factors, substance use, and fetal sex were assessed as potential confounders. Unadjusted and adjusted risks for gestational hypertension and preeclampsia were examined using odds ratios and 95% confidence intervals. FINDINGS: 3247 women were included in the study. Compared to non-supplement use, early and late supplement use were not significantly associated with the development of gestational hypertension or preeclampsia. The odds of developing gestational hypertension and preeclampsia were significantly reduced as the duration of folic acid-containing supplement use increased. CONCLUSION: Findings from this study suggest that the use of folic acid-containing supplements may mitigate the risk for gestational hypertension and preeclampsia.

The production of phantom partials due to nonlinearities in the structural components of the piano.

Phantom partials are anomalous overtones in the spectrum of the piano sound that occur at sum and difference frequencies of the natural overtones of the string. Although they are commonly assumed to be produced by forced longitudinal waves in the string, analysis of the sound of a piano produced by mechanically vibrating the soundboard while all the strings are damped indicates that phantom partials can occur in the absence of string motion. The magnitude of the effect leads to the conclusion that nonlinearity in the non-string components may be responsible for some of the power in the phantom partials.

Risk of gestational hypertension and preeclampsia in women who discontinued or continued antidepressant medication use during pregnancy.

PURPOSE: This study aimed to examine the association between discontinued and continued use of antidepressants and risk for gestational hypertension (GH) and preeclampsia (PE). METHODS: Data from the MotherToBaby pregnancy studies from 2004 to 2014 were analyzed to compare women who discontinued antidepressant use ˂20 weeks of gestation (discontinuers) and women who continued antidepressant use ≥20 weeks of gestation (continuers) to non-users for risk of GH (blood pressure ≥140/90 mmHg on two or more occasions at ≥20 weeks of gestation) and PE (GH with proteinuria). Maternal data, including exposures and study outcomes, were collected through multiple phone interviews. Medical records were used to validate outcomes. Odds ratios (ORs) and 95 % confidence intervals were estimated using logistic regression. Risk for GH and PE were also assessed within antidepressant drug classes. RESULTS: Data from 3471 women were analyzed. Continuers were significantly at risk for GH (adjusted odds ratios (aOR) 1.83; 95 % CI 1.05, 3.21) after adjustment. Analyses by drug class showed that continued use of serotonin-norepinephrine reuptake inhibitors (SNRI) increased risk for GH; however, of the 21 women who continued to use SNRI, only 3 developed GH. Continuers who used two or more antidepressant drug classes had increased risk for PE. Selective serotonin reuptake inhibitors or other antidepressant use was not associated with increased risk for GH or PE. No significant associations with PE or GH were found for discontinuers. CONCLUSIONS: Results suggest that women who continued to use antidepressants in the second half of pregnancy are at risk for GH and PE. No significant association was found among discontinuers.

Changes in Postpartum Insulin Requirements for Patients with Well-Controlled Type 1 Diabetes.

Objective To compare postpartum with preconception insulin doses in well-controlled (HbA1c ≤ 7.4%) type 1 diabetes mellitus (T1DM) and to characterize differences in postpartum insulin dosing based on infant feeding. Study Design The primary outcome in this retrospective cohort was the change in total daily insulin (TDI) from preconception to postpartum. Insulin administration (continuous subcutaneous insulin infusion [CSII] vs. multiple daily injections [MDI]), HbA1c, body mass index (BMI), and infant feeding were abstracted. Results We identified 44 women with T1DM and HbA1c ≤ 7.4%. Preconception mean BMI was 24.6 ± 3.6 kg/m(2) and median (interquartile range [IQR]) HbA1c was 6.4 (6.0-6.9)%. Of these, 73% used CSII and 27% used MDI. Additionally, 80% of patients reported exclusive breastfeeding, 7% were exclusively formula feeding, and 13% used both breast milk and formula. Median (IQR) preconception TDI was 0.64 (0.49-0.69) U/kg/day, and postpartum: 0.39 (0.30-0.50) U/kg/day. Postpartum TDI was 34% lower than preconception TDI (p = 0.02). There was no difference in the postpartum TDI in patients who were breast versus formula feeding or when comparing CSII with MDI. Conclusion There was a significant decrease in the TDI required postpartum when compared with preconception. Dosages do not seem to be impacted by administration route or breastfeeding. These findings warrant consideration when dosing postpartum insulin in patients with T1DM.

Maternal and neonatal outcomes in women with twin pregnancies with excessive gestational weight gain.

OBJECTIVE: To determine if an excessive rate of gestational weight gain (GWG) in twin pregnancies is associated with adverse obstetric outcomes. METHODS: Retrospective cohort study of twin pregnancies delivered at the University of California, San Diego 2001-2014. Women were included if they had adequate or excessive rates of GWG as determined by Institute of Medicine guidelines. Demographic and outcome variables were collected by chart review. RESULTS: Four hundred and eighty-nine twin pregnancies met inclusion criteria. Of which, 40.5% had adequate rates of GWG and 41.5% had excessive rates of GWG. The rates of preterm birth and gestational diabetes were similar between the two groups. Gestational hypertension and preeclampsia were more common in women with excessive GWG (37.9% versus 19.7%; p < 0.01). This finding persisted in multivariate analysis. The mean birth weight percentiles were higher in the excessive GWG group and these women were also less likely to have an infant with a birth weight <10th percentile (21.4% versus 35.9%, p < 0.01). CONCLUSIONS: Excessive GWG is associated with a higher risk for gestational hypertension and preeclampsia, but no other adverse perinatal outcomes. Infants born to mothers with excessive GWG are less likely to be small for gestational age than those born to women with adequate GWG.

Continuous Subcutaneous Insulin Infusion versus Multiple Daily Injections of Insulin for the Management of Type 1 Diabetes Mellitus in Pregnancy: Association with Neonatal Chemical Hypoglycemia.

OBJECTIVE: We hypothesized that patients with type 1 diabetes mellitus (T1DM) who were managed during their pregnancy with a continuous subcutaneous insulin infusion (CSII) would have a lower incidence of neonatal hypoglycemia (NH) than patients managed with multiple daily injections (MDI) of insulin. STUDY DESIGN: This was a retrospective cohort of 95 women with T1DM who delivered singleton, term neonates between 2007 and 2014. The primary outcome was incidence of NH (capillary plasma glucose ≤ 45 mg/dL) in the first 24 hours after birth. RESULTS: The incidence of NH was 66.0% (62/95). The NH rate was significantly higher in women managed with CSII versus MDI (62 vs. 38%, p = 0.024). Neonates with NH had a higher birth weight (3,867 ± 658 vs. 3,414 ± 619 g, p = 0.002). When analyzing intrapartum glucose management, mothers of neonates with NH had significantly less time managed on an insulin infusion (median interquartile range 7 [3.5-30.5] vs. 17.5 [2.0-17.5] hours, p = 0.014). In multivariable analysis, only maternal body mass index (BMI) (p = 0.035) and time on an insulin infusion (p = 0.043) were significantly associated with NH. CONCLUSION: In our population of patients with T1DM, CSII was more prevalent in the NH group; however, when controlling for other factors, intrapartum glucose management and early maternal BMI were the only variables associated with NH.

Axial vibrations of brass wind instrument bells and their acoustical influence: Experiments.

It has recently been proposed that the effects of structural vibrations on the radiated sound of brass wind instruments may be attributable to axial modes of vibration with mode shapes that contain no radial nodes [Kausel, Chatziioannou, Moore, Gorman, and Rokni, J. Acoust. Soc. Am. 137, 3149-3162 (2015)]. Results of experiments are reported that support this theory. Mechanical measurements of a trumpet bell demonstrate that these axial modes do exist in brass wind instruments. The quality factor of the mechanical resonances can be on the order of 10 or less, making them broad enough to encompass the frequency range of previously reported effects attributed to bell vibrations. Measurements of the input impedance show that damping bell vibrations can result in impedance changes of up to 5%, in agreement with theory. Measurements of the acoustic transfer function demonstrate that the axial vibrations couple to the internal sound field as proposed, resulting in changes in the transfer function of approximately 1 dB. In agreement with theory, a change in the sign of the effect is observed at the frequency of the structural resonance.

Early Second Trimester Weight Gain in Obese Women Predicts Excessive Gestational Weight Gain in Pregnancy.

OBJECTIVE: To assess gestational weight gain (GWG) in obese women to determine an inflection point that identifies women at risk for excessive weight gain. STUDY DESIGN: This is an observational prospective cohort study of pregnancies managed through the UC San Diego Maternal Weight and Wellness Program from 2011 to 2014. The primary outcome was total gestational weight gain. GWG was categorized as inadequate (<11 pounds), adequate (11-20 pounds), and excessive (>20 pounds) based on Institute of Medicine (IOM) recommendations. Other outcomes were GWG by trimester and postpartum weight retention. Bivariate and multivariate analyses were used to assess factors associated with GWG. RESULTS: Ninety-five patients had a mean prepregnancy body mass index (BMI) of 41.9 ± 8.9 kg/m(2) and a net weight gain of 21.9 ± 19 pounds. First trimester GWG was -0.3 ± 4.9 pounds, second trimester was 10.4 ± 10.8 pounds, and third trimester was 11.4 ± 8.5 pounds for all participants. Women who exceeded IOM recommendations accelerated weight gain at 12-14 weeks and gained a majority of weight during the second trimester. Weight gain of more than two pounds at 12-14 weeks had a 96 % positive predictive value (95 % CI 79-99) for excessive GWG. Postpartum women with excessive GWG retained more weight than those with inadequate GWG (10.7 ± 15.6 pounds compared with -13.6 ± 10.9 pounds, P < 0.001). On multiple linear regression GWG by trimester was predictive of total GWG with second and third trimester GWG having the greatest effect on total GWG. Prepregnancy BMI and gestational diabetes were not predictors of total GWG. CONCLUSIONS: Obese women at risk for excessive GWG may be identified as early as 12-14 weeks and gain most weight during the second trimester. GWG less than 11 pounds resulted in significant postpartum weight loss among obese women.

Axial vibrations of brass wind instrument bells and their acoustical influence: Theory and simulations.

Previous work has demonstrated that structural vibrations of brass wind instruments can audibly affect the radiated sound. Furthermore, these broadband effects are not explainable by assuming perfect coincidence of the frequency of elliptical structural modes with air column resonances. In this work a mechanism is proposed that has the potential to explain the broadband influences of structural vibrations on acoustical characteristics such as input impedance, transfer function, and radiated sound. The proposed mechanism involves the coupling of axial bell vibrations to the internal air column. The acoustical effects of such axial bell vibrations have been studied by extending an existing transmission line model to include the effects of a parasitic flow into vibrating walls, as well as distributed sound pressure sources due to periodic volume fluctuations in a duct with oscillating boundaries. The magnitude of these influences in typical trumpet bells, as well as in a complete instrument with an unbraced loop, has been studied theoretically. The model results in predictions of input impedance and acoustical transfer function differences that are approximately 1 dB for straight instruments and significantly higher when coiled tubes are involved or when very thin brass is used.

First trimester gestational diabetes screening - Change in incidence and pharmacotherapy need.

AIMS: Adopting recommendations of the International Association of Diabetes in Pregnancy Study Groups (IADPSG) and the California Diabetes and Pregnancy Program, our institution implemented early gestational diabetes (GDM) screening. Our objective was to compare GDM diagnosis rates using the standard two-step approach versus early screening, and secondarily to compare pharmacotherapy needs and perinatal outcomes. METHODS: This retrospective study included singleton pregnancies diagnosed between 7/2010 and 6/2012. Two cohorts were compared; those diagnosed via two-step screening versus early screening diagnosis: HbA1c≥5.7% (39 mmol/mol) or fasting plasma glucose (FPG)≥92 mg/dL at ≤24 weeks gestation, or an abnormal 2-h oral glucose tolerance test (GTT) between 24 and 28 weeks. We calculated the rate of diagnosis, analyzed the need for pharmacotherapy, and reviewed neonatal outcomes. RESULTS: A total of 2652 patients were screened. GDM was diagnosed in 5.3% with two-step screening and 9.4% with early screening. Of those diagnosed via early screening with HbA1c, FPG, or both HbA1c and FPG, 49.2%, 66.7%, and 78.9% respectively required pharmacotherapy. In contrast, of those diagnosed with a 2-h GTT, 30.6% required pharmacotherapy (p<0.001). When controlling for confounders in a multivariable regression, BMI is most predictive of medication requirements (aOR 1.13, 95% CI 1.08-1.18, p<0.001). There were no differences in mean birth weight (3240±619 g vs. 3179±573 g, p=0.51) and macrosomia rates (7% vs. 2.5%, p=0.12). CONCLUSION: Implementing early screening nearly doubled the incidence of GDM. Patients with early screening had a greater need for pharmacotherapy, but BMI was the best predictor of this outcome. There was no significant difference in neonatal outcomes.

Maternal High-Fat Feeding Increases Placental Lipoprotein Lipase Activity by Reducing SIRT1 Expression in Mice.

This study investigated how maternal overnutrition and obesity regulate expression and activation of proteins that facilitate lipid transport in the placenta. To create a maternal overnutrition and obesity model, primiparous C57BL/6 mice were fed a high-fat (HF) diet throughout gestation. Fetuses from HF-fed dams had significantly increased serum levels of free fatty acid and body fat. Despite no significant difference in placental weight, lipoprotein lipase (LPL) protein levels and activity were remarkably elevated in placentas from HF-fed dams. Increased triglyceride content and mRNA levels of CD36, VLDLr, FABP3, FABPpm, and GPAT2 and -3 were also found in placentas from HF-fed dams. Although both peroxisome proliferator-activated receptor-γ (PPARγ) and CCAAT/enhancer binding protein-α protein levels were significantly increased in placentas of the HF group, only PPARγ exhibited a stimulative effect on LPL expression in cultured JEG-3 human trophoblasts. Maternal HF feeding remarkably decreased SIRT1 expression in placentas. Through use of an SIRT1 activator and inhibitor and cultured trophoblasts, an inhibitory effect of SIRT1 on LPL expression was demonstrated. We also found that SIRT1 suppresses PPARγ expression in trophoblasts. Most importantly, inhibition of PPARγ abolished the SIRT1-mediated regulatory effect on LPL expression. Together, these results indicate that maternal overnutrition induces LPL expression in trophoblasts by reducing the inhibitory effect of SIRT1 on PPARγ.

Coupling of transverse and longitudinal waves in piano strings.

The existence of longitudinal waves in vibrating piano strings has been previously established, as has their importance in producing the characteristic sound of the piano. Modeling of the coupling between the transverse and longitudinal motion of strings indicates that the amplitude of the longitudinal waves are quadratically related to the transverse displacement of the string, however, experimental verification of this relationship is lacking. In the work reported here this relationship is tested by driving the transverse motion of a piano string at only two frequencies, which simplifies the task of unambiguously identifying the constituent signals. The results indicate that the generally accepted relationship between the transverse motion and the longitudinal motion is valid. It is further shown that this dependence on transverse displacement is a good approximation when a string is excited by the impact of the hammer during normal play.

Normal modes of a small gamelan gong.

Studies have been made of the normal modes of a 20.7 cm diameter steel gamelan gong. A finite-element model has been constructed and its predictions for normal modes compared with experimental results obtained using electronic speckle pattern interferometry. Agreement was reasonable in view of the lack of precision in the manufacture of the instrument. The results agree with expectations for an axially symmetric system subject to small symmetry breaking. The extent to which the results obey Chladni's law is discussed. Comparison with vibrational and acoustical spectra enabled the identification of the small number of modes responsible for the sound output when played normally. Evidence of non-linear behavior was found, mainly in the form of subharmonics of true modes. Experiments using scanning laser Doppler vibrometry gave satisfactory agreement with the other methods.