Multiheterodyne spectroscopy with optical frequency combs generated from a continuous-wave laser.

Dual-drive Mach-Zehnder modulators were utilized to produce power-leveled optical frequency combs (OFCs) from a continuous-wave laser. The resulting OFCs contained up to 50 unique frequency components and spanned more than 200 GHz. Simple changes to the modulation frequency allowed for agile control of the comb spacing. These OFCs were then utilized for broadband, multiheterodyne measurements of CO2 using both a multipass cell and an optical cavity. This technique allows for robust measurements of trace gas species and alleviates much of the cost and complexity associated with the use of femtosecond OFCs produced with mode-locked pulsed lasers.

Toxicity and exposure of an adenovirus containing human interferon alpha-2b following intracystic administration in cynomolgus monkeys.

The safety and toxicokinetics of SCH 721015, an adenovirus encoding the human interferon alpha-2b gene, and Syn3 (SCH 209702), a novel excipient, were assessed in cynomolgus monkeys administered intravesical doses of 2.5 × 10E11 or 1.25 × 10E13 particles SCH 721015 in 25 mg Syn3 or 25 mg Syn3 alone on study days 1 and 91. There was no systemic toxicity. Monkeys dosed with SCH 721015 in Syn3 were positive for SCH 721015-specific DNA in the urine for 2 to 3 days following each dose and had interferon alpha-2b protein in the urine for 1-3 days after a single dose and in fewer animals after a second dose. Intracystic administration was associated with inflammation and focal/multifocal ulceration in the urinary bladder and irritation in the ureters and urethra at necropsy. The physical trauma from catheterization and filling/emptying of the bladder was likely a contributing factor and Syn3 exacerbated the trauma. There was nearly complete resolution of these findings 2 months after the last dose. The trauma to the bladder likely contributed to low, transient systemic exposure to Syn3, SCH 721015 and human interferon protein. The results of this study support the clinical investigation of SCH 721015 in Syn3.

Optical and mechanical design of a telescope for lunar spectral irradiance measurements from a high-altitude aircraft.

We have designed a non-imaging telescope for measurement of the spectral irradiance of the moon. The telescope was designed to be integrated into a wing pod of a National Aeronautics and Space Administration ER-2 research aircraft to measure lunar spectral irradiance during flight. The telescope and support system were successfully flown in August 2018 at altitudes near 21 km and at speeds of ∼760 km/h. The wing pod in which the telescope is mounted has an opening through which the moon can be observed. The mount exposes the telescope to high winds, low pressures, temperatures near -60 °C, and vibrations both due to flight and due to the motion of the aircraft on the ground. This required a telescope design with high thermal stability and high resistance to shock. The optical design of the telescope is optimized to have high throughput and spatially uniform transmission from 380 nm to 1000 nm over a field of view about three times the angular size of the moon as viewed from the Earth. The final design resulted in a telescope with singlet design incorporating a 139.7 mm lens with an effective focal length of 377 mm and a field of view of 1.6°. The light from the telescope is introduced into an integrating sphere, which destroys the image and the polarization for measurement by a fiber-coupled spectroradiometer. Herein, we present an overview of the instrument and support system with emphasis on the telescope design.

Precise methane absorption measurements in the 1.64 µm spectral region for the MERLIN mission.

In this article we describe a high-precision laboratory measurement targeting the R(6) manifold of the 2ν3 band of 12CH4. Accurate physical models of this absorption spectrum will be required by the Franco-German, Methane Remote Sensing LIDAR (MERLIN) space mission for retrievals of atmospheric methane. The analysis uses the Hartmann-Tran profile for modeling line shape and also includes line-mixing effects. To this end, six high-resolution and high signal-to-noise absorption spectra of air-broadened methane were recorded using a frequency-stabilized cavity ring-down spectroscopy apparatus. Sample conditions corresponded to room temperature and spanned total sample pressures of 40 hPa - 1013 hPa with methane molar fractions between 1 µmol mol-1 and 12 µmol mol-1. All spectroscopic model parameters were simultaneously adjusted in a multispectrum nonlinear least-squares fit to the six measured spectra. Comparison of the fitted model to the measured spectra reveals the ability to calculate the room-temperature, methane absorption coefficient to better than 0.1% at the on-line position of the MERLIN mission. This is the first time that such fidelity has been reached in modeling methane absorption in the investigated spectral region, fulfilling the accuracy requirements of the MERLIN mission. We also found excellent agreement when comparing the present results with measurements obtained over different pressure conditions and using other laboratory techniques. Finally, we also evaluated the impact of these new spectral parameters on atmospheric transmissions spectra calculations.

Cumulative and compensatory effects of competence and incompetence on depressive symptoms in children.

The authors tested 5 hypotheses from a competency-based model of child depression using classification and regression tree analysis. The authors obtained measures of 5 domains of competency (i.e., academic competence, social acceptance, sports competence, physical attractiveness, and behavioral conduct) and depressive symptoms that were derived from parent, teacher, peer, and self-reports on 1,063 3rd- and 6th-grade children. Results suggested that (a) multiple domains of competence related to depressive symptoms, (b) significant others' positive evaluations in multiple domains have a cumulative inverse relation to depressive symptoms, (c) negative evaluations in multiple domains have a cumulative but positive relation to depressive symptoms, (d) positive evaluations in one domain somewhat compensate for negative evaluations in another domain, and (e) negative evaluations in one domain offset positive evaluations in another domain.

Assessment of a multiple-dose drug interaction between ezetimibe, a novel selective cholesterol absorption inhibitor and gemfibrozil.

OBJECTIVE: Ezetimibe is a novel lipid-lowering drug that prevents intestinal absorption of dietary and biliary cholesterol leading to significant reduction in total-C, LDL-C, Apo B, and TG and increases in HDL-C in patients with hypercholesterolemia. Gemfibrozil, a fibric acid derivative, is an effective lipid-modulating agent that increases serum high-density lipoprotein cholesterol and decreases serum TG. The objective of this study was to evaluate the potential for a pharmacokinetic (PK) interaction between ezetimibe and gemfibrozil. METHODS: This was a randomized, open-label, 3-way crossover, multiple-dose study in 12 healthy adult male volunteers. All subjects received the following 3 treatments orally for 7 days: ezetimibe 10 mg once daily, gemfibrozil 600 mg every 12 hours, and ezetimibe 10 mg once daily plus gemfibrozil 600 mg every 12 hours. A washout period of > or = 7 days separated the 3 treatments. In each treatment, blood samples were collected on day 7 to assess the steady-state PK of ezetimibe and gemfibrozil. The oral bioavailability of ezetimibe coadministered with gemfibrozil relative to each drug administered alone was evaluated with an analysis-of-variance model. RESULTS: Ezetimibe was rapidly absorbed and extensively conjugated to its glucuronide metabolite. Ezetimibe did not alter the bioavailability (based on AUC) of gemfibrozil. The mean AUC0-12 of gemfibrozil was 74.7 and 74.1 microg h/ml with and without ezetimibe coadministration, respectively (log-transformed geometric mean ratio (GMR) = 99.2; 90% confidence interval (CI) = 92 - 107%). Conversely, gemfibrozil significantly (p < 0.05) increased the plasma concentrations of ezetimibe and total ezetimibe (i.e. ezetimibe plus ezetimibe-glucuronide). Exposure to ezetimibe and total ezetimibe was increased approximately 1.4-fold and 1.7-fold, respectively (CI = 109 - 173% for ezetimibe and 142 - 190% for total ezetimibe), however, this increase was not considered to be clinically relevant. Ezetimibe and gemfibrozil administered alone or concomitantly for 7 days was well tolerated. CONCLUSIONS: The coadministration of ezetimibe and gemfibrozil in patients is unlikely to cause a clinically significant drug interaction. The coadministration of these agents is a promising approach for patients with mixed dyslipidemia. Additional clinical studies are warranted.

Sample size and multiple regression analysis.

Despite the development of procedures for calculating sample size as a function of relevant effect size parameters, rules of thumb tend to persist in designs of multiple regression studies. One explanation for their persistence may be the difficulty in formulating a reasonable a priori value of an effect size to be detected. This article presents methods for calculating effect sizes in multiple regression from a variety of perspectives and also introduces a new method based on an exchangeability structure among predictor variables. No single method is deemed superior, but rather examples show that a combination of methods is likely to be most valuable in many situations. A simulation provides a 2nd explanation for why rules of thumb for choosing sample size have persisted but also shows that the outcome of such underpowered studies will be a literature consisting of seemingly contradictory results.

The proof of the pudding: an illustration of the relative strengths of null hypothesis, meta-analysis, and Bayesian analysis.

Some methodologists have recently suggested that scientific psychology's over-reliance on null hypothesis significance testing (NHST) impedes the progress of the discipline. In response, a number of defenders have maintained that NHST continues to play a vital role in psychological research. Both sides of the argument to date have been presented abstractly. The authors take a different approach to this issue by illustrating the use of NHST along with 2 possible alternatives (meta-analysis as a primary data analysis strategy and Bayesian approaches) in a series of 3 studies. Comparing and contrasting the approaches on actual data brings out the strengths and weaknesses of each approach. The exercise demonstrates that the approaches are not mutually exclusive but instead can be used to complement one another.

Structural differences in parent and child reports of children's symptoms of depression and anxiety.

Two cohorts of public elementary school children and their parents (assessed 3 years apart) completed child and parent forms of the Children's Depression Inventory (CDI) and the Revised Children's Manifest Anxiety Scale (RCMAS). Assessments were conducted twice, once during the fall (N = 562) and again during the spring (N = 630) of the 6th grade. Factor analyses revealed 3 factors for each measure. Two of the 3 parent CDI factors manifested some degree of congruence with their counterparts from the child CDI. Similarly, 2 of the 3 RCMAS factors were somewhat congruent across informant types. Differences between parent and child factor structures suggest that parents' and children's reports focus on somewhat different aspects of child psychopathology, and they can make qualitatively different contributions to the multiaxial assessment of children.

Development of physical ability tests for police officers: a construct validation approach.

A construct validation approach was followed to affirm that 8 physical ability test events were significantly related to two important constructs underlying the job performance of police officers: strength and endurance. A sample of 115 incumbent police officers took 8 physical ability tests and were rated by supervisors on their physical performances in their job. LISREL methods were used to test the model specified, and a reasonable fit was achieved. Portions of the model were tested on an independent sample of 161 applicants; the fit of the model was again acceptable. A nomological network of relationships, in which strength and endurance factors correlated in expected directions with other physiological and demographic variables, was hypothesized and tested. Finally, the data were examined for potential gender differences and bias. Considerable differences were shown between men and women on both test and performance variables, and women would be overpredicted if a common regression line were used for selection purposes.

Prenatal maternal predictors of cognitive and emotional delays in children of adolescent mothers.

The present study examined relationships among prenatal characteristics of 121 adolescent mothers-including cognitive readiness for parenting, intelligence, social support, and personal adjustment-and intellectual-linguistic development, social-emotional functioning, and adaptive behavior in their children at three years of age. Only 28% of the children scored within normal ranges on all three types of outcomes. Intellectual and linguistic delays were predicted best by prenatal measures of maternal Performance IQ and social support from extended family. Socioemotional problems were predicted best by maternal internalizing problems and social support from partner and friends. Adaptive behavior was associated with parenting style. Implications for the early identification of high-risk children--and associated intervention programs--are discussed.

Personal adjustment during pregnancy and adolescent parenting.

This study examined "naturally occurring differences" in personal adjustment (social competence, behavior problems, and problem-solving skills) among representative groups of pregnant and nonpregnant adolescents and pregnant adults. Differences in parenting stress and parenting style were also assessed among a subsample of adolescent and adult mothers. Finally, the relationship between prenatally assessed personal adjustment and parenting was evaluated in the adolescent mother group. The contributions of important demographic characteristics (socioeconomic status and race) to both between- and within-group relationships were examined. Results suggested that pregnant adolescents were less socially competent and less proficient in their problem solving than their nonpregnant peers and that they exhibited more behavioral problems than a pregnant adult comparison group. Adolescent mothers displayed higher levels of parenting stress and were less responsive and sensitive in interactions with their infants than adult mothers. Support for the hypothesized link between prenatally assessed personal adjustment and adolescent parenting stress was found, whereas no relationship between socioeconomic status and race and parenting stress was established. These results suggest that intervention with young mothers identified during pregnancy as having personal problems might forestall parenting problems that arise during early child rearing.

Quantum phase transitions and continuous observation of spinor dynamics in an antiferromagnetic condensate.

Condensates of spin-1 sodium display rich spin dynamics due to the antiferromagnetic nature of the interactions in this system. We use Faraday rotation spectroscopy to make a continuous and minimally destructive measurement of the dynamics over multiple spin oscillations on a single evolving condensate. This method provides a sharp signature to locate a magnetically tuned separatrix in phase space which depends on the net magnetization. We also observe a phase transition from a two- to a three-component condensate at a low but finite temperature using a Stern-Gerlach imaging technique. This transition should be preserved as a zero-temperature quantum phase transition.

Number fluctuations and energy dissipation in sodium spinor condensates.

We characterize fluctuations in atom number and spin populations in F=1 sodium spinor condensates. We find that the fluctuations enable a quantitative measure of energy dissipation in the condensate. The time evolution of the population fluctuations shows a maximum. We interpret this as evidence of a dissipation-driven separatrix crossing in phase space. For a given initial state, the critical time to the separatrix crossing is found to depend exponentially on the magnetic field and linearly on condensate density. This crossing is confirmed by tracking the energy of the spinor condensate as well as by Faraday rotation spectroscopy. We also introduce a phenomenological model that describes the observed dissipation with a single coefficient.

High-flux beam source for cold, slow atoms or molecules.

We demonstrate and characterize a high-flux beam source for cold, slow atoms or molecules. The desired species is vaporized using laser ablation, then cooled by thermalization in a cryogenic cell of buffer gas. The beam is formed by particles exiting a hole in the buffer gas cell. We characterize the properties of the beam (flux, forward velocity, temperature) for both an atom (Na) and a molecule (PbO) under varying buffer gas density, and discuss conditions for optimizing these beam parameters. Our source compares favorably to existing techniques of beam formation, for a variety of applications.

Covariate imbalance and conditional size: dependence on model-based adjustments.

Analysis of covariance (ANCOVA) is frequently recommended to correct for covariate imbalance and to control conditional size of hypothesis tests in randomized designs. Such control, however, depends on the accuracy of the ANCOVA model used to make the adjustments. Examination of residuals together with knowledge of the subject matter are important for obtaining an accurate model. Stratified assignment procedures lessen the dependence of proper control of conditional size on the specific model used in the adjustment procedure.

Multitrait-Multimethod Comparisons Across Populations: A Confirmatory Factor Analytic Approach.

The advantages of multitrait-multimethod (MTMM) methodology and the power of maximum likelihood confirmatory factor analysis are combined in an ordered framework for the comparison of covariance structures and true means across populations. First, a sequence of tests of and between hierarchically nested confirmatory factor analytic models is described for the analysis of measurement equivalence and construct validity across populations. Second, a similar sequence of model comparisons is proposed for the detection of true score-observed score regression intercept differences and true mean differences between populations. The proposed procedure is contrasted with MANOVA comparisons of group means: (1) use of MANOVA assumes test equivalence and validity across populations, whereas the present procedure permits statistical analysis of these assumptions; (2) MANOVA bases discriminant function coefficients partially upon observed differences between groups, whereas the current procedure weights each variate according to its correlation with an underlying construct. The possibility of spurious results from MANOVA and verdical results from the proposed methodology is demonstrated via application of both procedures to an artificial data set.

Nonrandom assignment and the analysis of covariance in aging research.

A technique developed initially by Overall and Woodward for using nonrandom assignment in ANCOVA is reviewed. Though such a technique produces unbiased measures of treatment effects, this is only true when the assumptions of ANCOVA have been met and when group assignment is based on covariate scores. Limitations and potential applications for such a technique in gerontological research are reviewed.