Noise in homodyne detection

A simple but rigorous analysis of the important sources of noise in homodyne detection is presented. Output noise and signal-to-noise ratios are compared for direct detection, conventional (one-port) homodyning, and two-port homodyning, in which one monitors both output ports of a 50-50 beam splitter. It is shown that two-port homodyning is insensitive to local-oscillator quadrature-phase noise and hence provides (1) a means of detecting reduced quadrature-phase fluctuations (squeezing) that is perhaps more practical than one-port homodyning and (2) an output signal-to-noise ratio that can be a modest to significant improvement over that of one-port homodyning and direct detection

Role of Physical Activity on Bone Mineral Content in Young Children

Previous studies identifying factors that influence peak bone mass have typically focused on older children, although it has been suggested that environmental factors early in life also may be important in optimizing the genetic potential for bone gain1 . Physical activity and calcium intake are considered major environmental factors influencing bone mass accretion. Longitudinal studies beginning in childhood show that high activity early in life is associated with high adult bone density2,3. The long-term effect between bone mass accretion and early calcium intake is less clear, with most trials finding that the beneficial bone effect of high calcium intake does not persist once the supplementation is withdrawn4 . Results of several studies related to bone changes and physical activity that we conducted in young children are reviewed belo

Changing the Construct: Promoting Cross-Cultural Conversations in the Law School Classroom

Promoting cross-cultural awareness should be an important aspect of professionalism training in legal education. Cross-cultural awareness is essential to our students as they prepare to practice in an increasingly diverse domestic and international legal marketplace with competence and confidence. At the very least, faculty should help students avoid becoming the next lawyer or judge to be sanctioned for culturally off ensive behavior. More broadly, early and repeated faculty attention to cross-cultural issues can improve the learning environment for all students while they are still in law school. Although such training can be diffi cult and uncomfortable for both the professor and the students, it is far better for our students to make mistakes within the safety of the classroom, where the ramifications of their errors will not be career ending, and better if by learning from mistakes students develop cultural competencies that will serve them and their clients in their future careers. In short, promoting cross-cultural awareness is part of our obligation to educate our students in professionalism. Accordingly, this article provides a blueprint for incorporating these valuable but challenging discussions into the law school classroom. Part II of this article identifies the pedagogical and institutional advantages of infusing legal instruction with discussions designed to promote crosscultural awareness. Part III discusses how to create an effective and safe classroom environment for conducting cross-cultural discussions by assessing the classroom climate, establishing a respectful and approachable relationship with students, and developing the cultural literacy and emotional knowledge to lead cross-cultural conversations with sensitivity and openness. Part IV explores specific techniques and best practices for promoting cross-cultural conversations that raise or implicate diverse cultural assumptions and expectations. Part V suggests techniques for dealing with student resistance and classroom incivility, and Part VI concludes the article

Scientific applications of frequency-stabilized laser technology in space

A synoptic investigation of the uses of frequency-stabilized lasers for scientific applications in space is presented. It begins by summarizing properties of lasers, characterizing their frequency stability, and describing limitations and techniques to achieve certain levels of frequency stability. Limits to precision set by laser frequency stability for various kinds of measurements are investigated and compared with other sources of error. These other sources include photon-counting statistics, scattered laser light, fluctuations in laser power, and intensity distribution across the beam, propagation effects, mechanical and thermal noise, and radiation pressure. Methods are explored to improve the sensitivity of laser-based interferometric and range-rate measurements. Several specific types of science experiments that rely on highly precise measurements made with lasers are analyzed, and anticipated errors and overall performance are discussed. Qualitative descriptions are given of a number of other possible science applications involving frequency-stabilized lasers and related laser technology in space. These applications will warrant more careful analysis as technology develops

Muscle-bone Relationships in the Lower Leg of Healthy Pre-pubertal Females and Males

Muscle-bone relationships in healthy pre-pubertal children were investigated using four muscle measures as predictors of tibial strength: 66% tibia cross-sectional muscle area (CSMA) by pQCT; leg lean mass (LLM) by DXA; and muscle power (Power) and force (Force) measured during a two-footed jump. Polar strength strain index (pSSI), a calculated surrogate for bone strength at the 20% distal tibia, was obtained on 105 (54 male) self-assessed pre-pubertal children. The amount of muscle (CSMA, LLM) may influence bone strength more than muscle strength (Power, Force) during periods of rapid growth. Correlations and multiple regression partial-R values from models controlling for age, sex, height and weight were obtained for each muscle predictor. CSMA, LLM, Power and Force were positively correlated with pSSI (R=0.84, 0.92, 0.85; 0.66, respectively, all p\u3c 0.01). Partial-R values were highest for LLM (partial-R=0.21), similar for CSMA and Power (0.14, 0.15, respectively) and lowest for Force (0.04) in predicting pSSI. Muscle predictors were associated with total and cortical area (R=0.59 to 0.90; p\u3c 0.01 for all), but not cortical vBMD at the 20% distal tibia site. These data support relationships between muscle predictors and bone parameters measured by pQCT in healthy pre-pubertal children

Solute effects on edge dislocation pinning in complex alpha-Fe alloys

Reactor pressure vessel steels are well-known to harden and embrittle under neutron irradiation, mainly because of the formation of obstacles to the motion of dislocations, in particular, precipitates and clusters composed of Cu, Ni, Mn, Si and P. In this paper, we employ two complementary atomistic modelling techniques to study the heterogeneous precipitation and segregation of these elements and their effects on the edge dislocations in BCC iron. We use a special and highly computationally efficient Monte Carlo algorithm in a constrained semi-grand canonical ensemble to compute the equilibrium configurations for solute clusters around the dislocation core. Next, we use standard molecular dynamics to predict and analyze the effect of this segregation on the dislocation mobility. Consistently with expectations our results confirm that the required stress for dislocation unpinning from the precipitates formed on top of it is quite large. The identification of the precipitate resistance allows a quantitative treatment of atomistic results, enabling scale transition towards larger scale simulations, such as dislocation dynamics or phase field.Fil: Pascuet, Maria Ines Magdalena. Consejo Nacional de Investigaciones Científicas y Técnicas; Argentina. Comision Nacional de Energia Atomica. Centro Atomico Constituyentes. Departamento de Materiales; ArgentinaFil: Martínez, E.. Los Alamos National High Magnetic Field Laboratory; Estados UnidosFil: Monnet, G.. EDF–R&D; FranciaFil: Malerba, L.. SCK•CEN. Structural Materials Expert Group. Nuclear Materials Institute; Bélgic

Marine litter education boosts children’s understanding and self-reported actions

Marine litter is a significant environmental problem inherently linked to individuals’ purchasing, use and disposal behaviour. This research examined 176 British schoolchildren’s (aged 8–13 years) baseline marine litter understanding and self-reported actions, and tested the impact of an educational intervention. All children participated in the educational intervention and completed a pre- and post-intervention questionnaire. At baseline, children were quite concerned about marine litter and recognised some of the causes and impacts of the problem. Children also reported taking a number of actions to help solve the problem. After the intervention, children were significantly more concerned, had a better understanding of the causes and negative impacts, and reported engaging in more actions to reduce the potential causes of marine litter. Understanding the perceptions and behaviours of children is crucial as they represent current and future actors and a potentially important source of social influence among their peers, parents and community