On the Generalizability of Time-of-Flight Convolutional Neural Networks for Noninvasive Acoustic Measurements.

Bulk wave acoustic time-of-flight (ToF) measurements in pipes and closed containers can be hindered by guided waves with similar arrival times propagating in the container wall, especially when a low excitation frequency is used to mitigate sound attenuation from the material. Convolutional neural networks (CNNs) have emerged as a new paradigm for obtaining accurate ToF in non-destructive evaluation (NDE) and have been demonstrated for such complicated conditions. However, the generalizability of ToF-CNNs has not been investigated. In this work, we analyze the generalizability of the ToF-CNN for broader applications, given limited training data. We first investigate the CNN performance with respect to training dataset size and different training data and test data parameters (container dimensions and material properties). Furthermore, we perform a series of tests to understand the distribution of data parameters that need to be incorporated in training for enhanced model generalizability. This is investigated by training the model on a set of small- and large-container datasets regardless of the test data. We observe that the quantity of data partitioned for training must be of a good representation of the entire sets and sufficient to span through the input space. The result of the network also shows that the learning model with the training data on small containers delivers a sufficiently stable result on different feature interactions compared to the learning model with the training data on large containers. To check the robustness of the model, we tested the trained model to predict the ToF of different sound speed mediums, which shows excellent accuracy. Furthermore, to mimic real experimental scenarios, data are augmented by adding noise. We envision that the proposed approach will extend the applications of CNNs for ToF prediction in a broader range.

Multi-Level Information Storage Using Engineered Electromechanical Resonances of Piezoelectric Wafers: A Concept Piezoelectric Quick Response (PQR) Code.

A piezoelectric-based method for information storage is presented. It involves engineering the polarization profiles of multiple piezoelectric wafers to enhance/suppress specific electromechanical resonances. These enhanced/suppressed resonances can be used to represent multiple frequency-dependent bits, thus enabling multi-level information storage. This multi-level information storage is demonstrated by achieving three information states for a ternary encoding. Using the three information states, we present an approach to encode and decode information from a 2-by-3 array of piezoelectric wafers that we refer to as a concept Piezoelectric Quick Response (PQR) code. The scaling relation between the number of wafers used and the cumulative number of information states that can be achieved with the proposed methodology is briefly discussed. Potential applications of this methodology include tamper-evident devices, embedded product tags in manufacturing/inventory tracking, and additional layers of security with existing information storage technologies.

Prevalence and Clinical Attributes of Congenital Microcephaly - New York, 2013-2015.

Congenital Zika virus infection can cause microcephaly and other severe fetal neurological anomalies (1). To inform microcephaly surveillance efforts and assess ascertainment sources, the New York State Department of Health and the New York City Department of Health and Mental Hygiene sought to determine the prevalence of microcephaly in New York during 2013-2015, before known importation of Zika virus infections. Suspected newborn microcephaly diagnoses were identified from 1) reports submitted by birth hospitals in response to a request and 2) queries of a hospital administrative discharge database for newborn microcephaly diagnoses. Anthropometric measurements, maternal demographics, and pregnancy characteristics were abstracted from newborn records from both sources. Diagnoses were classified using microcephaly case definitions developed by CDC and the National Birth Defects Prevention Network (NBDPN) (2). During 2013-2015, 284 newborns in New York met the case definition for severe congenital microcephaly (prevalence = 4.2 per 10,000 live births). Most newborns with severe congenital microcephaly were identified by both sources; 263 (93%) were identified through hospital requests and 256 (90%) were identified through administrative discharge data. The proportions of newborns with severe congenital microcephaly who were black (30%) or Hispanic (31%) were higher than the observed proportions of black (15%) or Hispanic (23%) infants among New York live births. Fifty-eight percent of newborns with severe congenital microcephaly were born to mothers with pregnancy complications or who had in utero or perinatal infections or teratogenic exposures, genetic disorders, or family histories of birth defects.

High frequency signal acquisition using a smartphone in an undergraduate teaching laboratory: Applications in ultrasonic resonance spectra.

A simple and inexpensive approach to acquiring signals in the megahertz frequency range using a smartphone is described. The approach is general, applicable to electromagnetic as well as acoustic measurements, and makes available to undergraduate teaching laboratories experiments that are traditionally inaccessible due to the expensive equipment that are required. This paper focuses on megahertz range ultrasonic resonance spectra in liquids and solids, although there is virtually no upper limit on frequencies measurable using this technique. Acoustic resonance measurements in water and Fluorinert in a one dimensional (1D) resonant cavity were conducted and used to calculate sound speed. The technique is shown to have a precision and accuracy significantly better than one percent in liquid sound speed. Measurements of 3D resonances in an isotropic solid sphere were also made and used to determine the bulk and shear moduli of the sample. The elastic moduli determined from the solid resonance measurements agreed with those determined using a research grade vector network analyzer to better than 0.5%. The apparatus and measurement technique described can thus make research grade measurements using standardly available laboratory equipment for a cost that is two-to-three orders of magnitude less than the traditional measurement equipment used for these measurements.

The acoustic nonlinearity parameter in Fluorinert up to 381 K and 13.8 MPa.

This work reports on the determination of the acoustic nonlinearity parameter, B/A, from measured sound speed data, in Fluorinert FC-43 at temperatures up to 381 K and pressures up to 13.8 MPa using the thermodynamic method. Sound speed was measured using Swept Frequency Acoustic Interferometry at 11 pressures between ambient and 13.8 MPa along 6 isotherms between ambient and 381 K. Second-order least-squares polynomial fits of measured sound speeds were used to determine temperature and pressure dependence. A room temperature B/A = 11.7 was determined and this parameter was found to increase by a factor of 2.5 over the temperature/pressure range investigated.

Linking air pollution data and adverse birth outcomes: environmental public health tracking in New York State.

BACKGROUND: Studies investigating associations between ambient air pollution and fetal growth and gestational duration have reported inconclusive findings. OBJECTIVES: The study goal was to use the Environmental Public Health Tracking Network to describe the association between exposure to particulate matter (PM2.5) and ozone and term low birth weight (TLBW) in New York State. METHODS: Birth data for the years 2001-2006 were linked to Census data and hierarchical Bayesian modeled air pollution data. Daily 8-hour maximums for ozone and daily average PM2.5 estimates were averaged by trimester and exposure quartiles. The Environmental Public Health Tracking Academic Center for Excellence at Rutgers University partnered with New York and several other states to create a statistical program that uses logistic regression to determine the association between air pollution exposure and TLBW. RESULTS: There were no consistent dose-response relationships between the pollutants and TLBW. Ozone exposure was associated with a higher risk of TLBW only in the first trimester, but these results were not statistically significant. Exposure to the third quartile of ozone for the full gestational period had negative associations with TLBW (odds ratio = 0.86; 95% confidence interval, 0.81-0.92). CONCLUSION: Collaboration within the Environmental Public Health Tracking Network to share methods and data for research proved feasible and efficient in assessing the relationship of air pollutants to adverse birth outcomes. This study finds little evidence to support positive associations between exposure to ozone or PM2.5 and TLBW in New York State.

Cold spells and the risk of hospitalization for asthma: New York, USA 1991-2006.

PURPOSE: A study was conducted to investigate whether prolonged periods of very cold temperatures were associated with an increased risk of hospitalization for asthma. METHODS: Hospitalization admissions with a principal diagnosis of asthma were identified in New York State, USA, for the months November through April from 1991 to 2006. A cold spell was defined as three or more consecutive days where the daily mean of universal apparent temperature (UAT) within a week prior to admission was at the 10th percentile or less. The percentage change in asthma hospitalizations during and after a cold spell was compared to the average daily number of hospitalizations preceding the cold spell using time series analysis. RESULTS: The average temperature during winter cold spells (December through March) was -15 °C, compared to -6 and -2 °C for cold spells in November and April, respectively. Cold spells during the winter months were associated with a mean decline of 4.9 % in asthma admissions statewide (95 % CI -7.8, -1.9 %). After a cold spell, no statistically significant changes were apparent during the winter months, but asthma hospitalizations increased after cold spells in the transitional months of November (mean = 9.6, 95 % CI 5.5, 13.9 %) and April (mean = 5.0, 95 % CI 1.2, 9.0 %). CONCLUSIONS: The results suggest that during prolonged periods of severe cold asthmatics may adhere to medical guidelines and limit their exposure, thereby preventing exacerbations. They may be less likely to alter their behavior in the more moderate months of November and April.

Specific resonance mode enhancement and suppression using non-uniform polarization of piezoelectric wafers: Theory and experiments.

We present experimental demonstration of specific resonance mode enhancement and suppression in circular and rectangular piezoelectric wafers with engineered non-uniform polarization profiles. The polarization profiles are designed based on the electromechanical impedance response of non-uniformly polarized wafers as obtained from the theory. The circular wafers are fabricated with non-uniform polarization profiles that involve a central polarized region surrounded by an unpolarized region. The radius of the polarization zone is designed based on the condition for specific mode enhancement obtained from the electromechanical impedance response of non-uniformly polarized wafers. We actually show how the condition can not only be used to enhance but also to suppress electromechanical resonances. Two kinds of wafers are designed and fabricated to specifically suppress second and third radial modes respectively. Similarly, rectangular wafers are designed with two different kinds of non-uniform polarization profiles - the first of which enhances the second in-plane extensional mode in the impedance spectrum and the second polarization profile suppresses all the electromechanical resonances pertaining to the in-plane extensional modes and selectively excites only the in-plane bending modes. The proposed approach of using non-uniformly polarized wafers finds application in designing multi-frequency sensors/transducers, frequency-tuned receivers, acoustic beamforming, and other non-traditional applications such as information storage.

Genetic Algorithm-Wavelet Transform Feature Extraction for Data-Driven Acoustic Resonance Spectroscopy.

Acoustic resonance spectroscopy (ARS) enables highly accurate measurement of the properties (geometry/material) of a structure based on the structure's natural vibrational resonances. In general, measuring a specific property in multibody structures presents a significant challenge due to the complex overlapping peaks within the resonance spectrum. We present a technique for extracting useful features from a complex spectrum by isolating resonance peaks that are sensitive to the measured property and insensitive to other properties (noise peaks). We isolate specific peaks by selecting frequency regions of interest and performing wavelet transformation, where the frequency regions and wavelet scales are tuned via a genetic algorithm. This contrasts greatly from the traditional wavelet transformation/decomposition techniques, which use a large number of wavelets at different scales to represent the signal, including the noise peaks, and results in a large feature size, thus decreasing machine learning (ML) generalizability. We provide a detailed description of the technique and demonstrate the feature extraction technique, for example, regression and classification problems. We observe reductions of 95% and 40% in regression and classification errors, respectively, when using the genetic algorithm/wavelet transform feature extraction, compared to using no feature extraction, or using wavelet decomposition, which is common in optical spectroscopy. The feature extraction has potential to significantly increase the accuracy of spectroscopy measurements based on a wide range of ML techniques. This would have significant implications for ARS, as well as other data-driven methods for other types of spectroscopy, e.g., optical.

Multilevel Frequency-Specific Information Storage Using Engineered Electromechanical Resonances in Piezoelectric Wafer Arrays.

Multilevel information storage methods have the potential for increasing storage density and improving information security through obfuscation. Taking inspiration from the color quick response codes, we have developed a method for encoding layers of information in an array of thin piezoelectric wafers. Information storage is accomplished by altering the size of the circular polarization domain of individual wafers to engineer the response of the electromechanical resonances. By using this approach, we can store one layer of information per electromechanical resonance. In this study, we experimentally demonstrate this approach on a 20-element piezoelectric wafer array with up to two layers of information storage using binary encoding. We first discuss the relevant theory behind the proposed approach and the method for designing the polarization profiles for these wafer arrays to enable multilevel information storage. The effect of the size of the polarization domain on the strength of the electromechanical resonances and optimal size to enhance/suppress these resonances is discussed. Last, we describe how the proposed approach could be used to encode four or more layers of frequency-specific information. The proposed technology finds application in embedded barcodes, product tags, tamper-evident seals, and other secure applications such as shipping sensitive materials/containers.

Reproductive outcomes among former Love Canal residents, Niagara Falls, New York.

Love Canal, located in Niagara Falls, NY, and among the earliest and most significant hazardous waste sites in the United States, first came to public attention in 1978. In this study, researchers evaluated 1,799 live births from 1960 through 1996 to 980 women who formerly lived in the Love Canal Emergency Declaration Area and were of reproductive age sometime during that time period. Using Upstate New York and Niagara County as external comparison populations, standardized incidence ratios with 95% confidence intervals were calculated for low birth weight, preterm birth, small for gestational age, and congenital malformations, and unadjusted proportions of male to female births were calculated. Internal comparisons among the infants were also performed according to several measures of potential exposure using generalized estimating equations. The results indicated a statistically significant elevated risk of preterm birth among children born on the Love Canal prior to the time of evacuation and relocation of residents from the Emergency Declaration Area, using Upstate New York as the standard population (standardized incidence ratio=1.40; 95% confidence interval: 1.01, 1.90). Additionally, the ratio of male to female births was lower for children conceived in the Emergency Declaration Area (sex ratio=0.94 versus sex ratio=1.05 in the standard population) and the frequency of congenital malformations was greater than expected among Love Canal boys born from 1983 to 1996 (standardized incidence ratio=1.50 when compared to Upstate New York), although in both cases the 95% confidence interval included the null value. Finally, increased risk for low birth weight infants among mothers who lived closest to the Canal as children was found (odds ratio=4.68; 95% confidence interval: 1.24, 17.66), but this estimate was limited due to small numbers (n=4). The study adds to the knowledge of the possible reproductive effects from exposure to chemicals arising from hazardous waste; however, given the small number of some events, the qualitative nature of the exposure assessment, and possibility of spurious associations due to multiple comparisons, the findings should be interpreted cautiously.

The effect of a transducer's spatial averaging on an elastodynamic guided wave's wavenumber spectrum.

Elastodynamic guided waves propagate in an elastic solid which makes it difficult, if not impractical, to place a receiving transducer in the direct path of the propagating wave (as one would for an acoustic wave in a fluid medium). To account for this, receiving transducers are often placed on the surface of the solid waveguide such that the transducer surface is parallel to the wave propagation direction. This transducer orientation introduces spatial averaging, which causes the received signal to have an altered signal amplitude and mode bias. We investigate both of these effects and present a simple model from which we derive a scaling-ratio expression that describes the effects of spatial averaging. We then test its performance using finite-element simulations that incorporate "real-world" assumptions (e.g., transient waves, piezoelectric effects, etc.). The results from the simulations demonstrate that the scaling-ratio can characterize the effects resulting from spatial averaging. The scaling-ratio expression will be particularly useful when designing experiments involving high frequency (small wavelength) guided waves. Lastly, the proposed scaling-ratio expression could be applied to other sensing methods, like Laser Doppler Vibrometry (LDV) or piezoelectric waveguides with inter-digitated transducers, because of its generality. However, the authors are careful to note that the scaling-ratio expression is not intended as a replacement of multi-physics analysis or good experimental design, and the effects of spatial averaging should be avoided whenever possible.

A Physics-Based Signal Processing Approach for Noninvasive Ultrasonic Characterization of Multiphase Oil-Water-Gas Flows in a Pipe.

A signal processing technique is presented for determining the composition of multiphase oil-water-gas flow in a pipe using noninvasive ultrasonic speed of sound measurements from a transmitter-receiver pair bonded to diametrically opposite sides of a pipe. A linear chirp excitation is used to send broadband ultrasonic energy that propagates in two paths from transmitter to receiver such as: 1) a wave through the pipe wall and then the multiphase mixture and 2) ultrasonic guided waves along the pipe wall in the circumferential direction. As the ultrasonic attenuation of the multiphase mixture increases, the amplitude of the signal through the fluid mixture decreases relative to that of circumferential guided waves, making it difficult to determine the time of arrival of the fluid-path signal and, hence, the speed of sound in the mixture. The proposed signal processing technique overcomes this challenge by using: 1) a guided wave subtraction approach to suppress the strength of guided wave signals relative to the fluid-path signal and 2) a Gaussian reconstruction approach for synthetic enhancement of the fluid-path signal by output signal reconstruction at frequencies corresponding to peak transmission of ultrasonic energy. The efficacy of the technique is demonstrated using experiments carried out in a field-scale flow loop with varying compositions of oil-water-gas mixtures. It is shown that the proposed approach can enhance the signal detectability by approximately 20 dB in comparison with the traditional approach that does not utilize guided wave subtraction and also improves the gas tolerance of composition measurements up to 20% in gas volume fraction.

Noninvasive Acoustic Measurements in Cylindrical Shell Containers.

Acoustic time-of-flight (ToF) measurements enable noninvasive material characterization, acoustic imaging, and defect detection and are commonly used in industrial process control, biomedical devices, and national security. When characterizing a fluid contained in a cylinder or pipe, ToF measurements are hampered by guided waves, which propagate around the cylindrical shell walls and obscure the waves propagating through the interrogated fluid. We present a technique for overcoming this limitation based on a broadband linear chirp excitation and cross correlation detection. By using broadband excitation, we exploit the dispersion of the guided waves, wherein different frequencies propagate at different velocities, thus distorting the guided wave signal while leaving the bulk wave signal in the fluid unperturbed. We demonstrate the measurement technique experimentally and using numerical simulation. We characterize the technique performance in terms of measurement error, signal-to-noise-ratio, and resolution as a function of the linear chirp center frequency and bandwidth. We discuss the physical phenomena behind the guided bulk wave interactions and how to utilize these phenomena to optimize the measurements in the fluid.

Concentrations of selected organochlorines and chlorobenzenes in the serum of former Love Canal residents, Niagara Falls, New York.

BACKGROUND: Love Canal, in Niagara Falls, NY is among the earliest and most significant hazardous waste sites in the USA, but no study has ever measured chemical body burdens in nearby residents to document that human exposure occurred. This study measured concentrations of selected organochlorines and chlorinated benzenes in archived serum samples collected from former Love Canal residents. METHODS: We analyzed serum samples collected from 373 former residents in 1978-1979 for compounds disposed of at Love Canal, and we compared their concentrations according to surrogate indicators of exposure such as residential proximity, adjusting for potential confounders. RESULTS: Three compounds were detectable in the serum of most participants: 1,2,4-trichlorobenzene (1,2,4-TCB), beta-hexachlorocyclohexane (beta-HCH) and 1,2-dichlorobenzene (1,2-DCB). Concentrations of 1,2,4-TCB and 1,2-DCB were 2-14 times greater among persons who at the time their blood was collected lived closest to the Canal compared to those living further away. We found no consistent trends for beta-HCH with respect to any exposure definition. CONCLUSIONS: These results provide evidence that residential proximity to Love Canal contributed to the body burden of certain contaminants, and helps validate the use of surrogate exposure measures in health effect studies. Further surveillance of the Love Canal cohort is warranted.

A broadband wavelet implementation for rapid ultrasound pulse-echo time-of-flight measurements.

A broadband wavelet approach to ultrasonic pulse-echo time-of-flight measurements is described. The broadband approach significantly reduces the time required for frequency-dependent pulse-echo measurements, enabling studies of dynamic systems ranging from biological systems to solid-state phase transitions. The described broadband approach is demonstrated in parallel with the more traditional frequency stepping approach to perform ultrasound time-of-flight measurements inside a large volume Paris-Edinburgh press in situ at a synchrotron source. The broadband wavelet data acquisition process was found to be 1-2 orders of magnitude faster than the stepped-frequency approach, with no compromise on data quality or determined results.

Mortality among former Love Canal residents.

BACKGROUND: The Love Canal is a rectangular 16-acre, 10-ft deep chemical waste landfill situated in a residential neighborhood in Niagara Falls, New York. This seriously contaminated site first came to public attention in 1978. No studies have examined mortality in the former residents of the Love Canal neighborhood (LC). OBJECTIVE: The aim of this study was to describe the mortality experience of the former LC residents from the years 1979-1996. METHODS: From 1978 to 1982, 6,181 former LC residents were interviewed. In 1996, 725 deaths from 1979-1996 were identified in this cohort, using state and national registries. We compared mortality rates with those of New York State (NYS) and Niagara County. Survival analysis examined risks by potential exposure to the landfill. RESULTS: We were unable to demonstrate differences in all-cause mortality for either comparison population for 1979 1996. Relative to NYS, the standardized mortality ratio (SMR) was elevated [SMR = 1.39; 95% confidence interval (CI), 1.16-1.66] for death from acute myocardial infarction (AMI), but not relative to Niagara County. Death from external causes of injury was also elevated relative to both NYS and Niagara County, especially among women (SMR = 1.95; 95% CI, 1.25 2.90). CONCLUSIONS: The role of exposure to the landfill in explaining these excess risks is not clear given limitations such as multiple comparisons, a qualitative exposure assessment, an incomplete cohort, and no data on deaths prior to 1978. Lack of elevation for AMI when compared with Niagara County but not NYS suggests possible regional differences. However, direct cardiotoxic or neurotoxic effects from landfill chemicals or indirect effects mediated by psychological stress cannot be ruled out. Revisiting the cohort in the future could reveal patterns that are not yet apparent.

Ultrasonic Bessel beam generation from radial modes of piezoelectric discs.

We present comprehensive analytical and experimental investigations on ultrasonic Bessel beam generation from radial modes of piezoelectric disc transducers. The Bessel vibration pattern of the radial modes was experimentally measured using Laser Doppler Vibrometry and was found to be in very good agreement with those obtained from numerical simulations. Ultrasonic beam profiles from the first four radial modes of the piezoelectric disc were measured using a hydrophone in a water tank. The results obtained from the experimental scans were compared to the predictions from an analytical model and were found to be in very good agreement. Also, the Bessel beams generated from the radial modes (except the first) of the piezoelectric discs were found to have narrow beam width for the central lobe compared to those from an ideal piston source of same size. The proposed approach of using radial modes for Bessel beam generation finds applications in imaging, acoustic particle manipulation and trapping, and acousto-optics.

Accessibility of cooling centers to heat-vulnerable populations in New York State.

Introduction: Spending a few hours to cool down in a cooling center reduces the impact of heat on health. But limited or lack of accessibility of these facilities is often a barrier to their utilization. The objective of this study was to assess accessibility of the cooling centers to heat-vulnerable populations in New York State (NYS) by various modes of transportation. Methods: We estimate the proximity of 377 cooling centers to general and heat-vulnerable populations in NYS (excluding New York City (NYC)) and determine their accessibility via walking, public transportation and driving. Distances between tract populations and nearest cooling center, and between cooling centers and public transportation stops were estimated. Accessibility in four metropolitan regions was determined via public transportation while accessibility in heat-vulnerable rural areas was estimated via driving. Results: Distances to nearest cooling center ranged from 0 to 53.2 miles with only a third of NYS population within walking distance (0.5 miles) of a cooling center. About 51% of heat-vulnerable tracts were within 0.5 miles, with an average distance of 2.4 miles to the nearest cooling center. Within the four metro politan regions 80% of cooling centers within 0.5 miles of a public transportation stop. All cooling centers in heat-vulnerable tracts were accessible via public transportation. In rural heat-vulnerable tracts, driving distances averaged at about 18 miles. Conclusions: In urban areas many residents were not within walking distance of a cooling center, but most, and nearly all in the most heat-vulnerable areas, were within walking distance of public transportation to a cooling center. In rural locations distances were longer, and accessibility is a greater issue. Cooling centers can be a valuable resource for general and heat-vulnerable populations during an extreme heat event. When planning and implementing cooling centers, it is therefore important to improve accessibility and address other barriers that can hamper their utilization.

Maternal ambient heat exposure during early pregnancy in summer and spring and congenital heart defects - A large US population-based, case-control study.

BACKGROUND/OBJECTIVE: Few studies have assessed the effect of ambient heat during the fetal development period on congenital heart defects (CHDs), especially in transitional seasons. We examined and compared the associations between extreme heat and CHD phenotypes in summer and spring, assessed their geographical differences, and compared different heat indicators. METHODS: We identified 5848 CHD cases and 5742 controls (without major structural defects) from the National Birth Defects Prevention Study, a US multicenter, population-based case-control study. Extreme heat events (EHEs) were defined by using the 95th (EHE95) or 90th (EHE90) percentile of daily maximum temperature and its frequency and duration during postconceptional weeks 3-8. We used a two-stage Bayesian hierarchical model to examine both regional and study-wide associations. Exposure odds ratios (ORs) were calculated using multivariate logistic regression analyses, while controlling for potential confounding factors. RESULTS: Overall, we observed no significant relationships between maternal EHE exposure and CHDs in most regions during summer. However, we found that 3-11 days of EHE90 during summer and spring was significantly associated with ventricular septal defects (VSDs) study-wide (ORs ranged: 2.17-3.24). EHE95 in spring was significantly associated with conotruncal defects and VSDs in the South (ORs: 1.23-1.78). Most EHE indicators in spring were significantly associated with increased septal defects (both VSDs and atrial septal defects (ASDs)) in the Northeast. CONCLUSION: While generally null results were found, long duration of unseasonable heat was associated with the increased risks for VSDs and ASDs, mainly in South and Northeast of the US. Further research to confirm our findings is needed.