Comparison of generalized estimating equations and quadratic inference functions using data from the National Longitudinal Survey of Children and Youth (NLSCY) database

<p>Abstract</p> <p>Background</p> <p>The generalized estimating equations (GEE) technique is often used in longitudinal data modeling, where investigators are interested in population-averaged effects of covariates on responses of interest. GEE involves specifying a model relating covariates to outcomes and a plausible correlation structure between responses at different time periods. While GEE parameter estimates are consistent irrespective of the true underlying correlation structure, the method has some limitations that include challenges with model selection due to lack of absolute goodness-of-fit tests to aid comparisons among several plausible models. The quadratic inference functions (QIF) method extends the capabilities of GEE, while also addressing some GEE limitations.</p> <p>Methods</p> <p>We conducted a comparative study between GEE and QIF via an illustrative example, using data from the "National Longitudinal Survey of Children and Youth (NLSCY)" database. The NLSCY dataset consists of long-term, population based survey data collected since 1994, and is designed to evaluate the determinants of developmental outcomes in Canadian children. We modeled the relationship between hyperactivity-inattention and gender, age, family functioning, maternal depression symptoms, household income adequacy, maternal immigration status and maternal educational level using GEE and QIF. Basis for comparison include: (1) ease of model selection; (2) sensitivity of results to different working correlation matrices; and (3) efficiency of parameter estimates.</p> <p>Results</p> <p>The sample included 795, 858 respondents (50.3% male; 12% immigrant; 6% from dysfunctional families). QIF analysis reveals that gender (male) (odds ratio [OR] = 1.73; 95% confidence interval [CI] = 1.10 to 2.71), family dysfunctional (OR = 2.84, 95% CI of 1.58 to 5.11), and maternal depression (OR = 2.49, 95% CI of 1.60 to 2.60) are significantly associated with higher odds of hyperactivity-inattention. The results remained robust under GEE modeling. Model selection was facilitated in QIF using a goodness-of-fit statistic. Overall, estimates from QIF were more efficient than those from GEE using AR (1) and Exchangeable working correlation matrices (Relative efficiency = 1.1117; 1.3082 respectively).</p> <p>Conclusion</p> <p>QIF is useful for model selection and provides more efficient parameter estimates than GEE. QIF can help investigators obtain more reliable results when used in conjunction with GEE.</p

Anisotropic interactions of a single spin and dark-spin spectroscopy in diamond

The nitrogen-vacancy (N-V) center in diamond is a promising atomic-scale system for solid-state quantum information processing. Its spin-dependent photoluminescence has enabled sensitive measurements on single N-V centers, such as: electron spin resonance, Rabi oscillations, single-shot spin readout and two-qubit operations with a nearby 13C nuclear spin. Furthermore, room temperature spin coherence times as long as 58 microseconds have been reported for N-V center ensembles. Here, we have developed an angle-resolved magneto-photoluminescence microscopy apparatus to investigate the anisotropic electron spin interactions of single N-V centers at room temperature. We observe negative peaks in the photoluminescence as a function of both magnetic field magnitude and angle that are explained by coherent spin precession and anisotropic relaxation at spin level anti-crossings. In addition, precise field alignment unmasks the resonant coupling to neighboring dark nitrogen spins that are not otherwise detected by photoluminescence. The latter results demonstrate a means of investigating small numbers of dark spins via a single bright spin under ambient conditions.Comment: 13 pages, 4 figure

High-sensitivity diamond magnetometer with nanoscale resolution

We present a novel approach to the detection of weak magnetic fields that takes advantage of recently developed techniques for the coherent control of solid-state electron spin quantum bits. Specifically, we investigate a magnetic sensor based on Nitrogen-Vacancy centers in room-temperature diamond. We discuss two important applications of this technique: a nanoscale magnetometer that could potentially detect precession of single nuclear spins and an optical magnetic field imager combining spatial resolution ranging from micrometers to millimeters with a sensitivity approaching few femtotesla/Hz$^{1/2}$.Comment: 29 pages, 4 figure

Assessment of cardiac remodeling in asymptomatic mitral regurgitation for surgery timing: a comparative study of echocardiography and magnetic resonance imaging

<p>Abstract</p> <p>Background</p> <p>Early surgery is recommended for asymptomatic severe mitral regurgitation (MR), because of increased postoperative left ventricular (LV) dysfunction in patients with late surgery. On the other hand, recent reports emphasized a "watchful waiting" process for the determination of the proper time of mitral valve surgery. In our study, we compared magnetic resonance imaging (MRI) and transthoracic echocardiography to evaluate the LV and left atrial (LA) remodeling; for better definitions of patients that may benefit from early valve surgery.</p> <p>Methods</p> <p>Twenty-one patients with moderate to severe asymptomatic MR were evaluated by echocardiography and MRI. LA and LV ejection fractions (EFs) were calculated by echocardiography and MRI. Pulmonary veins (PVs) were measured from vein orifices in diastole and systole from the tangential of an imaginary circle that completed LA wall. Right upper PV indices were calculated with the formula; (Right upper PV diastolic diameter- Right upper PV systolic diameter)/Right upper PV diastolic diameter.</p> <p>Results</p> <p>In 9 patients there were mismatches between echocardiography and MRI measurements of LV EF. LV EFs were calculated ≥60% by echocardiography, meanwhile < 60% by MRI in these 9 patients. Severity of MR evaluated by effective regurgitant orifice area (EROA) didn't differ with preserved and depressed EFs by MRI (p > 0.05). However, both right upper PV indices (0.16 ± 0.06 vs. 0.24 ± 0.08, p: 0.024) and LA EFs (0.19 ± 0.09 vs. 0.33 ± 0.14, p: 0.025) were significantly decreased in patients with depressed EFs when compared to patients with normal EFs.</p> <p>Conclusions</p> <p>MRI might be preferred when small changes in functional parameters like LV EF, LA EF, and PV index are of clinical importance to disease management like asymptomatic MR patients that we follow up for appropriate surgery timing.</p

Clinicopathologic features of incidental prostatic adenocarcinoma in radical cystoprostatectomy specimens

<p>Abstract</p> <p>Background</p> <p>The aim of this study is to review all features of incidentally discovered prostate adenocarcinoma in patients undergoing radical cystoprostatectomy for bladder cancer.</p> <p>Methods</p> <p>The medical charts of 300 male patients who underwent radical cystoprostatectomy for bladder cancer between 1997 and 2005 were retrospectively reviewed. The mean age of the patients was 62 (range 51-75) years.</p> <p>Results</p> <p>Prostate adenocarcinoma was present in 60 (20%) of 300 specimens. All were acinar adenocarcinoma. Of these, 40 (66.7%) were located in peripheral zone, 20 (33.3%) had pT2a tumor, 12 (20%) had pT2b tumor, 22(36.7%) had pT2c and, 6 (10%) had pT3a tumor. Gleason score was 6 or less in 48 (80%) patients. Surgical margins were negative in 54 (90%) patients, and tumor volume was less than 0.5 cc in 23 (38.3%) patients. Of the 60 incidentally detected cases of prostate adenocarcinoma 40 (66.7%) were considered clinically significant.</p> <p>Conclusion</p> <p>Incidentally detected prostate adenocarcinoma is frequently observed in radical cystoprostatectomy specimens. The majority are clinically significant.</p

Scripts of Sexual Desire and Danger in US and Dutch Teen Girl Magazines: A Cross-National Content Analysis

The aim of this comparative quantitative content analysis was to investigate how US and Dutch teen girl magazines cover sexual desire (i.e., sexual wanting, and pleasure) and sexual danger (i.e., sexual risk, and negative physical/health consequences of sex). Relying on the sexual scripts framework and Hofstede’s cultural dimension of masculinity/femininity, we examined (a) how the coverage varied for boys and girls, (b) how it differed between the United States and the Netherlands, and (c) how gender differences varied by country. The sample comprised 627 sex-related feature stories from all 2006–2008 issues of three US (i.e., Seventeen, CosmoGirl! United States edition, and Teen) and three Dutch teen girl magazines (i.e., Fancy, CosmoGirl! Netherlands edition, and Girlz!). Overall, sexual wanting occurred more frequently in the US magazines than in the Dutch magazines. In the US coverage, boys’ sexual wanting received more attention than girls’ sexual wanting, whereas in the Dutch coverage sexual wanting was depicted equally often for boys and girls. The depiction of sexual pleasure did not vary by gender in either country, but was generally more visible in the Dutch magazines than in the US magazines. Sexual risks and the negative consequences of sex were associated with girls more than with boys, and were primarily depicted in the US magazines rather than in the Dutch magazines

Miller Early Childhood Sustained Home-visiting (MECSH) trial: design, method and sample description

<p>Abstract</p> <p>Background</p> <p>Home visiting programs comprising intensive and sustained visits by professionals (usually nurses) over the first two years of life show promise in promoting child health and family functioning, and ameliorating disadvantage. Australian evidence of the effectiveness of sustained nurse home visiting in early childhood is limited. This paper describes the method and cohort characteristics of the first Australian study of sustained home visiting commencing antenatally and continuing to child-age two years for at-risk mothers in a disadvantaged community (the Miller Early Childhood Sustained Home-visiting trial).</p> <p>Methods and design</p> <p>Mothers reporting risks for poorer parenting outcomes residing in an area of socioeconomic disadvantage were recruited between February 2003 and March 2005. Mothers randomised to the intervention group received a standardised program of nurse home visiting. Interviews and observations covering child, maternal, family and environmental issues were undertaken with mothers antenatally and at 1, 12 and 24 months postpartum. Standardised tests of child development and maternal-child interaction were undertaken at 18 and 30 months postpartum. Information from hospital and community heath records was also obtained.</p> <p>Discussion</p> <p>A total of 338 women were identified and invited to participate, and 208 were recruited to the study. Rates of active follow-up were 86% at 12 months, 74% at 24 months and 63% at 30 months postpartum. Participation in particular data points ranged from 66% at 1 month to 51% at 24 months postpartum. Rates of active follow-up and data point participation were not significantly different for the intervention or comparison group at any data point. Mothers who presented for antenatal care prior to 20 weeks pregnant, those with household income from full-time employment and those who reported being abused themselves as a child were more likely to be retained in the study. The Miller Early Childhood Sustained Home-visiting trial will provide Australian evidence of the effectiveness of sustained nurse home visiting for children at risk of poorer health and developmental outcomes.</p> <p>Trial registration</p> <p>ACTRN12608000473369</p

A Diamond Nanowire Single Photon Antenna

The development of a robust light source that emits one photon at a time is an outstanding challenge in quantum science and technology. Here, at the transition from many to single photon optical communication systems, fully quantum mechanical effects may be utilized to achieve new capabilities, most notably perfectly secure communication via quantum cryptography. Practical implementations place stringent requirements on the device properties, including stable photon generation, room temperature operation, and efficient extraction of many photons. Single photon light emitting devices based on fluorescent dye molecules, quantum dots, and carbon nanotube material systems have all been explored, but none have simultaneously demonstrated all criteria. Here, we describe the design, fabrication, and characterization of a bright source of single photons consisting of an individual Nitrogen-vacancy color center (NV center) in a diamond nanowire operating in ambient conditions. The nanowire plays a positive role in increasing the number of single photons collected from the NV center by an order of magnitude over devices based on bulk diamond crystals, and allows operation at an order of magnitude lower power levels. This result enables a new class of nanostructured diamond devices for room temperature photonic and quantum information processing applications, and will also impact fields as diverse as biological and chemical sensing, opto-mechanics, and scanning-probe microscopy.Comment: 16 pages, 4 figures, v2: Includes improved reference list; modified figure 1 to show a large array of NW and FDTD simulation of field profile; direct experimental comparsion of several bulk/NW devices in figure

Optimal left ventricular lead position assessed with phase analysis on gated myocardial perfusion SPECT

The aim of the current study was to evaluate the relationship between the site of latest mechanical activation as assessed with gated myocardial perfusion SPECT (GMPS), left ventricular (LV) lead position and response to cardiac resynchronization therapy (CRT). The patient population consisted of consecutive patients with advanced heart failure in whom CRT was currently indicated. Before implantation, 2-D echocardiography and GMPS were performed. The echocardiography was performed to assess LV end-systolic volume (LVESV), LV end-diastolic volume (LVEDV) and LV ejection fraction (LVEF). The site of latest mechanical activation was assessed by phase analysis of GMPS studies and related to LV lead position on fluoroscopy. Echocardiography was repeated after 6 months of CRT. CRT response was defined as a decrease of a parts per thousand yen15% in LVESV. Enrolled in the study were 90 patients (72% men, 67 +/- 10 years) with advanced heart failure. In 52 patients (58%), the LV lead was positioned at the site of latest mechanical activation (concordant), and in 38 patients (42%) the LV lead was positioned outside the site of latest mechanical activation (discordant). CRT response was significantly more often documented in patients with a concordant LV lead position than in patients with a discordant LV lead position (79% vs. 26%, p < 0.01). After 6 months, patients with a concordant LV lead position showed significant improvement in LVEF, LVESV and LVEDV (p < 0.05), whereas patients with a discordant LV lead position showed no significant improvement in these variables. Patients with a concordant LV lead position showed significant improvement in LV volumes and LV systolic function, whereas patients with a discordant LV lead position showed no significant improvements.Cardiovascular Aspects of Radiolog