Ultrahigh vacuum packaging and surface cleaning for quantum devices.

We describe design, implementation, and performance of an ultra-high vacuum (UHV) package for superconducting qubit chips or other surface sensitive quantum devices. The UHV loading procedure allows for annealing, ultra-violet light irradiation, ion milling, and surface passivation of quantum devices before sealing them into a measurement package. The package retains vacuum during the transfer to cryogenic temperatures by active pumping with a titanium getter layer. We characterize the treatment capabilities of the system and present measurements of flux tunable qubits with an average T1 = 84 µs and T2 echo=134µs after vacuum-loading these samples into a bottom loading dilution refrigerator in the UHV-package.

Non-equilibrium phonon generation and detection in microstructure devices.

We demonstrate a method to excite locally a controllable, non-thermal distribution of acoustic phonon modes ranging from 0 to ~200 GHz in a silicon microstructure, by decay of excited quasiparticle states in an attached superconducting tunnel junction (STJ). The phonons transiting the structure ballistically are detected by a second STJ, allowing comparison of direct with indirect transport pathways. This method may be applied to study how different phonon modes contribute to the thermal conductivity of nanostructures.

Preparation and detection of a mechanical resonator near the ground state of motion.

Cold, macroscopic mechanical systems are expected to behave contrary to our usual classical understanding of reality; the most striking and counterintuitive predictions involve the existence of states in which the mechanical system is located in two places simultaneously. Various schemes have been proposed to generate and detect such states, and all require starting from mechanical states that are close to the lowest energy eigenstate, the mechanical ground state. Here we report the cooling of the motion of a radio-frequency nanomechanical resonator by parametric coupling to a driven, microwave-frequency superconducting resonator. Starting from a thermal occupation of 480 quanta, we have observed occupation factors as low as 3.8 +/- 1.3 and expect the mechanical resonator to be found with probability 0.21 in the quantum ground state of motion. Further cooling is limited by random excitation of the microwave resonator and heating of the dissipative mechanical bath. This level of cooling is expected to make possible a series of fundamental quantum mechanical observations including direct measurement of the Heisenberg uncertainty principle and quantum entanglement with qubits.

Self-cooling of a micromirror by radiation pressure.

Cooling of mechanical resonators is currently a popular topic in many fields of physics including ultra-high precision measurements, detection of gravitational waves and the study of the transition between classical and quantum behaviour of a mechanical system. Here we report the observation of self-cooling of a micromirror by radiation pressure inside a high-finesse optical cavity. In essence, changes in intensity in a detuned cavity, as caused by the thermal vibration of the mirror, provide the mechanism for entropy flow from the mirror's oscillatory motion to the low-entropy cavity field. The crucial coupling between radiation and mechanical motion was made possible by producing free-standing micromirrors of low mass (m approximately 400 ng), high reflectance (more than 99.6%) and high mechanical quality (Q approximately 10,000). We observe cooling of the mechanical oscillator by a factor of more than 30; that is, from room temperature to below 10 K. In addition to purely photothermal effects we identify radiation pressure as a relevant mechanism responsible for the cooling. In contrast with earlier experiments, our technique does not need any active feedback. We expect that improvements of our method will permit cooling ratios beyond 1,000 and will thus possibly enable cooling all the way down to the quantum mechanical ground state of the micromirror.

A model study of capacitive micromachined ultrasonic transducers fabricated using atomic layer deposition process.

In this paper, we present the model study of capacitive micromachined ultrasonic transducers (CMUTs) fabricated by atomic layer deposition (ALD) technology, which uses a self-limiting binary reaction process to produce ultra-thin membranes. Advantages of ALD include precise control of membrane thickness, lower cost due to a reduction in the number of fabrication steps, the potential to use a large variety of materials, and increased reliability due to the enhanced surface quality of the membranes. These capabilities promise fabrication of transducers with superior operating characteristics. However, no study has yet documented sensitivity and power requirements for CMUTs created using ALD. We present here a first-order mechanical and equivalent circuit analysis along with a fabrication process to create and characterize CMUTs using ALD. Simulation results show that these systems have the potential for excellent sensitivity and decreased power requirements. Work to test the fabricated elements is currently underway.

Development of a noninvasive ultrasound color M-mode means of estimating pulmonary vascular resistance in pediatric pulmonary hypertension: mathematical analysis, in vitro validation, and preliminary clinical studies.

BACKGROUND: Accurate determination of pulmonary vascular resistance (PVR) is an important component in the evaluation and treatment of pediatric patients with pulmonary hypertension. We developed a novel technique, based on the concept of flow propagation, to estimate PVR noninvasively. The hypothesis is that changes in PVR cause changes in the velocity propagation (Vel(prop)) within the main pulmonary artery and that Vel(prop) can be quantified using color M-mode imaging. METHODS AND RESULTS: We tested the hypothesis using mathematical modeling, in vitro experiments, and preliminary clinical studies. The mathematical model showed that pressure and velocity tracings are closely correlated in time and that 6 to 18 ms time resolution was needed to resolve propagation times within typical main pulmonary artery lengths (2 to 5 cm). The in vitro experiments demonstrated that it was feasible to use color M-mode to measure Vel(prop) and that Vel(prop) correlated well with downstream resistance [y=(-1.01x)+22.77; R=0.96]. The method was then evaluated on patients undergoing acute pulmonary reactivity testing (n=22 measurements). Good correlation between Vel(prop) and PVR was found [y=(-1.71x)+26.0; R=0.90; SEE=2.41]. CONCLUSION: This newly developed method promises to be useful in the noninvasive evaluation of adults and children with pulmonary hypertension.

Artificial neural network-based method of screening heart murmurs in children.

BACKGROUND: Early recognition of heart disease is an important goal in pediatrics. Efforts in developing an inexpensive screening device that can assist in the differentiation between innocent and pathological heart murmurs have met with limited success. Artificial neural networks (ANNs) are valuable tools used in complex pattern recognition and classification tasks. The aim of the present study was to train an ANN to distinguish between innocent and pathological murmurs effectively. METHODS AND RESULTS: Using an electronic stethoscope, heart sounds were recorded from 69 patients (37 pathological and 32 innocent murmurs). Sound samples were processed using digital signal analysis and fed into a custom ANN. With optimal settings, sensitivities and specificities of 100% were obtained on the data collected with the ANN classification system developed. For future unknowns, our results suggest the generalization would improve with better representation of all classes in the training data. CONCLUSION: We demonstrated that ANNs show significant potential in their use as an accurate diagnostic tool for the classification of heart sound data into innocent and pathological classes. This technology offers great promise for the development of a device for high-volume screening of children for heart disease.

Computerized patient records: current and future opportunities.

Although computerized patient record (CPR) technology holds tangible promise for improvements in the quality of patient care, its penetration into physician practices has been slow at best. This article describes the operational and quality of care benefits of CPR implementation and the barriers to implementation. These include technology limitations, cultural factors, lack of standards, downtime fears, security and privacy concerns, and the lack of alignment of economic incentives. The article also provides non-radical approaches (i.e., simpler and cheaper) ways to harness technology to improve office efficiencies and patient care.

Reports of pain by children undergoing rapid palatal expansion.

PURPOSE: This study described and quantified the prevalence, timing, and intensity of pain during the expansion phase of rapid palatal expansion (RPE) in children and investigated whether pain was related to age, sex, or rate of expansion. METHODS: Ninety-seven children, 38 males and 59 females, between the ages of 5 to 13 years (median 7.7 years) undergoing RPE procedures with the Hyrax, Dentaurum, Newtown, PA, appliance were surveyed. The appliance was expanded with either one or two turns (1/4 mm/turn) per day based on the provider's preference. The child's pain response was measured no more than 5 minutes after each turn for the entire period of expansion using both the Facial Pain Scale and the Color Analog Scale. RESULTS: Ninety-eight percent of the children reported at least some pain during RPE. The highest levels of pain were reported during the first 10 turns with the greatest intensity during the first 6 turns and a steadily decreasing amount of pain thereafter. Pain medication was taken after 7% of the expansion turns in the study with the majority of children taking the medication during the first 6 turns. Forty-eight percent of the children took pain medication at least once during the expansion phase of RPE. There was no difference in either reported pain or use of pain medication based on age, sex, or stage of dentition. During the first 10 turns, children whose rate of expansion was two turns/day were more likely to report pain and take pain medication than children whose rate of expansion was one turn/day, thereafter there were no differences. CONCLUSIONS: The vast majority of children undergoing the active phase of rapid palatal expansion with a Hyrax appliance report pain. The pain generally occurs during the initial phase of expansion and diminishes thereafter, with two turns/day resulting in reports of pain greater than those expanding only once/day.

Dental development and molar root length in children with cleidocranial dysplasia.

Cleidocranial dysplasia (CD) is an autosomal dominant skeletal disorder with characteristic dental findings of numerous supernumerary teeth and noneruption of permanent teeth. This investigation compared the dental development and root lengths of the mandibular first permanent molar in 11 CD patients with those of 22 healthy, normal children matched for race, age and sex. The results showed that children with CD experienced a delay in dental development of approximately 3 years compared with normal children (P < 0.05). In addition, the root lengths of the mandibular first permanent molar were significantly longer than those of the comparison children (17.8 +/- 1.6 mm vs 13.6 +/- 1.2 mm (P < 0.001). This study thus revealed two significant clinical features of CD: 1) severe delay in dental development, and 2) excessive root lengths of mandibular permanent first molars. These features may be important in the pathogenesis of delayed dental eruption observed in this disorder.

Williams syndrome--oral presentation of 45 cases.

Forty-five patients with Williams syndrome (WS) were evaluated for oral abnormalities. The mean age of the patients was 9.25 years, the median age was 6.7 years, and the majority (62.2%) were male. Hypodontia was present in 11.1% of the patients. Abnormal tooth morphology was noted in 12.5% of the primary dentitions and 40.7% of the permanent dentitions. With the exception of the primary mandibular central incisors of males, all mesiodistal incisor crown dimensions were statistically significantly smaller when compared with norms (P < 0.05). At least one hypoplastic enamel defect was present in 9.4% of patients with primary teeth and in 18.5% with permanent teeth. No patients exhibited generalized enamel hypoplasia. More than half of the patients (59.1%) were both caries and restoration free, while only 13.6% presented with clinically active caries. Tongue thrusting was present in 67.7% of the sample, while more than 50% of the patients present with excessive interdental spacing. Patients exhibited a higher than normal prevalence of Class II and III occlusions, open and deep bites and anterior crossbites. No single dental finding was pathognomonic of WS, however two constellations of findings, each occurring in approximately one-third of the sample, were observed: 1) microdontia, anterior crossbite, tongue thrusting, and excessive interdental spacing, and 2) microdontia, deep or open bite, and excessive interdental spacing.

Bottle-feeding and malocclusion: is there an association?

To determine whether there is an association between bottle-feeding and malocclusion, a case control study was conducted by means of a questionnaire sent to the parents of 737 patients aged 10 to 12 years from a large private pediatric dental practice. Questions included method and duration of infant feeding, type of nipple used, pacifier use, sucking habits, history of orthodontic treatment, and parental orthodontic history. Analysis of valid responses (N = 454) showed need for treatment to be associated only with history of parental orthodontic treatment (P less than 0.05). A trend toward association of bottle-feeding with need for orthodontic treatment was found in the increasing need for treatment with increasing exposure to bottle, but was of marginal significance (P = 0.058).