The effect of leaf geometry on the microwave backscatter from leaves

An understanding of microwave backscatter from canopies is required in the development of methods to derive biophysical variables from Synthetic Aperture Radar (SAR) data. Physically based microwave backscatter models of canopies rely upon simulating the average scatter properties of plant components accurately. This work compares the Radar Cross Section (RCS) of idealized shapes (i.e. curved plates, rectangular plates, elliptical discs) used in the currently available radiative transfer simulations with the observed scatter from real leaves at a frequency of 10GHz using VV polarization. This preliminary work suggests that these simple representations do not characterize leaves adequately. Effects associated with the surface roughness of leaves are observed tobe particularly important.     

Enhancement of Surfactants in Nanoparticles Produced by an Electrospray Aerosol Generator

Electrospray aerosol generators (EAGs) disperse conducting solutions into air, promptly neutralize the particles to remove the excess charge, and evaporate the residual solvent with a dry air flow. For solutions containing multiple solutes, the particles may become enhanced in the more surface-active solutes. The extent of the enhancement was estimated for nanoparticles electrosprayed from a solution containing NaCl and surfactant sodium dodecyl sulfate (SDS) mixed in a 9:1 weight ratio. A tandem particle mobility analyzer was used to quantify the hygroscopic growth factor (GF). The relative fractions of NaCl and SDS in the particles were estimated from the measured GFs assuming that NaCl and SDS take up water independently of each other. The nanoparticles were considerably enhanced in SDS relative to the starting solution, with the NaCl:SDS weight ratio increasing with the distance from the EAG electrified capillary tip to the neutralizer, and reaching ～1:1 at the longest distances probed. The enhancement in SDS likely occurred during particle fission events as particles traveled from the capillary to the neutralizer. This study has practical ramifications for aerosol nanotechnology and aerosol-assisted drug delivery, which rely on EAG as an instrument of choice for nanoparticle generation.

Copyright 2012 American Association for Aerosol Research     

Adaptive Cluster Sampling: Estimating Density of Spatially Autocorrelated Larvae of the Sea Lamprey with Improved Precision

Adaptive cluster sampling (ACS) provides researchers with an alternative technique to estimate the abundance of rare or spatially clustered organisms, but its application in field investigations has been limited to relatively few studies. We used ACS to estimate parameters of a spatially autocorrelated population of larval sea lampreys, Petromyzon marinus, in Wilmot Creek, a Lake Ontario tributary. When compared with simple random sampling (SRS), ACS significantly increased catch per sample as well as the percentage of samples that contained larvae. Although ASC-generated samples are spatially biased, the use of established formulae enabled us to calculate unbiased estimators of mean larval density and variance. With ACS, variance was reduced, improving the precision around estimates of mean density, however; increased precision came at the price of greater sampling effort. When variance was adjusted for effort, ASC provided equal or greater efficiency than SRS in 33% of sampling events, with no apparent site or seasonal bias. Based on the knowledge that larval sea lampreys are spatially aggregated, we anticipated that ACS would result in higher precision for a greater proportion of sampling events. Nonetheless, we consider ACS to be a useful technique for evaluating larval sea lamprey populations and anticipate increased application for investigating other spatially over-dispersed species.     

Psychosocial predictors of employment status among men living with spinal cord injury.

Objective: To explore the relationship between employment status and community access, perceived community discrimination, social support from significant others, depressive symptoms, and gender-related variables for 83 men living with spinal cord injury. Study Design: Correlational research. Setting: Internet-based investigation employing spinal cord injury listservs. Main Outcome Measure: Participant employment status. Results: A forced-entry hierarchical logistic regression indicated that means of injury, community access and perceived community discrimination, social support from significant others, depressive symptoms, and men’s adherence to masculine norms for primacy of work, self-reliance, and emotional control significantly predicted employment status. Conclusions: Psychosocial variables such as community access, perceived discrimination, social support from significant others, depressive symptoms, and gender identity represent important and understudied predictors of employment status among men living with spinal cord injury. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Management of hysteroscopic surgery complications

Hysteroscopic surgery is considered a safe, routine gynecologic procedure performed in the OR and in office settings. Complications are rare; however, when complications do occur they can be severe and rapid. The surgical team members must understand the significance of patient monitoring and proper equipment operation to ensure positive patient outcomes. This article discusses complications from intravasation of various distending media used during hysteroscopy and the complication of hyponatremia. A physiologic approach to these problems enhances awareness of the significance of patient monitoring during hysteroscopic procedures.     

Photocurrent spectroscopy for quantum-well intermixed photonic integrated circuit design

Photocurrent spectroscopy is used to characterize band edges in quantum-well intermixed InGaAsP material lattice matched to InP. The band edge absorption data is used as a design tool to predict the dc performance of electroabsorption modulators, and is shown to agree well with data obtained from actual devices. In addition, we demonstrate the presence of an exciton peak in InGaAsP quantum wells, and present its evolution as a function of quantum-well intermixing and reverse bias voltage.     

Modeling of the optical characteristics for twin-channel laser (TCL) structures

The twin-channel laser (TCL) structure was the first laser design which incorporated the use of optical gain in the regions between the elements of an array-type device. In this paper, we describe the important parameters affecting the performance of TCL devices and extend our concepts to multielement (n > 2) laser arrays. Our calculations indicate that the presence of a uniform gain distribution over the width of the array is necessary for the excitation of the fundamental array mode and to achieve a single lobe far field. Secondly, lateral array mode stability is drastically reduced for arrays having many elements (n > 2) and will be difficult to achieve in practice. Lastly, we find that the near-field intensity in laser array structures is more spatially sensitive to asymetric perturbations induced by either current or geometry nonuniformities than single-element devices. We believe that some of these problems can possibly be minimized by the use of a new laser array geometry which incorporates an unequal number of array elements along the cavity length in order to spatially filter the unwanted array modes.     

Role play for assessing the social competence of psychiatric patients.

This study examined the validity and utility of role play for assessing social competence of chronic psychiatric patients. Demographically matched groups of patients with schizophrenia (n?=?57), schizoaffective disorder (n?=?16), major affective disorder (n?=?33), and a nonpatient control group (n?=?20) were assessed on a role-play test, interview measures of role functioning in the community, and a problem-solving discussion with a significant other. A subsample was reassessed on the same instruments 6 months later. Behavior on the role-play test discriminated the groups, was highly correlated with ratings on the other measures, and was relatively stable over the retest interval. The results were interpreted as providing strong support for the value of role play as a general measure of social functioning. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Sexually transmitted disease among married Zambian women: the role of male and female sexual behaviour in prevention and management

Two methods of endotracheal intubation of patients lying on the ground were compared for ease and speed of intubation and minimization of complications in a crossover study of prehospital-oriented emergency physicians. Intubation of a mannequin was attempted by the physicians in either a left lateral decubitus (LLD) position or a kneeling (K) position, followed by the alternate position. The LLD position afforded more rapid intubation, better glottic visualization, and less dental trauma. Eighty-seven percent of physicians completely visualized the glottis in the LLD position, versus 33% of the K position group. Intubation times were 10.5 versus 14.6 seconds in the LLD and K positions, respectively (P < .001). The LLD position is a more effective position (in a mannequin model) than the K position for intubation of patients found lying on the ground, a frequent situation in prehospital care.