Verbs Matter: A Tutorial for Determining Verb Difficulty.

PURPOSE: Research indicates that when teaching grammatical forms to children, the verbs used to model specific grammatical inflections matter. When learning grammatical forms, children have higher performance when they hear many unique verb forms that vary in their frequency and phonological complexity. In this tutorial, we demonstrate a method for identifying and characterizing a large number of verbs based on their frequency and complexity. METHOD: We selected verbs from an open-access database of transcribed child language samples. We extracted verbs produced by 5- to 8.9-year-old children in four morphosyntactic contexts: regular past tense -ed, third person singular -s, is/are + verb+ing, and do/does questions. We ranked verbs based on their frequency of occurrence across transcripts. We also coded the phonological complexity of each verb. We coded each verb as high or low frequency and high or low phonological complexity. RESULTS: The synthesis yielded 129 unique verbs used in the regular past tense -ed context, 107 verbs used in the third person singular -s context, 69 verbs used in the is/are + verb+ing context, and 16 verbs used in the do/does question context. We created tables for each form that include the frequency rankings and phonological complexity scores for every verb. CONCLUSIONS: Clinicians may use the verb lists, frequency ratings, and phonological complexity scores to help identify verbs to incorporate into assessment and intervention sessions with children. Researchers and clinicians may use the step-by-step approach presented in the tutorial to identify verbs or other syntactic components used in different morphosyntactic contexts or produced by individuals of different demographics in different speaking contexts.

Using Computerized Language Analysis to Evaluate Grammatical Skills.

Purpose Conducting in-depth grammatical analyses based on language samples can be time consuming. Developmental Sentence Scoring (DSS) and the Index of Productive Syntax (IPSyn) analyses provide detailed information regarding the grammatical profiles of children and can be conducted using free computer-based software. Here, we provide a tutorial to support clinicians' use of computer-based analyses to aid diagnosis and develop and monitor treatment goals. Method We analyzed language samples of a 5-year-old with developmental language disorder and an adolescent with Down syndrome using computer-based software, Computerized Language Analysis. We focused on DSS and IPSyn analyses. The tutorial includes step-by-step procedures for conducting the analyses. We also illustrate how the analyses may be used to assist in diagnosis, develop treatment goals focused on grammatical targets, and monitor progress on these treatment goals. Conclusion Clinicians should consider using Computerized Language Analysis's IPSyn and DSS analyses to support grammatical language assessments used to aid diagnosis, develop treatment goals, and monitor progress on these treatment goals. Supplemental Material https://doi.org/10.23641/asha.12021141.

Multi-wavelength microflow cytometer using groove-generated sheath flow.

A microflow cytometer was developed that ensheathed the sample (core) fluid on all sides and interrogated each particle in the sample stream at four different wavelengths. Sheathing was achieved by first sandwiching the core fluid with the sheath fluid laterally via fluid focusing. Chevron-shaped groove features fabricated in the top and bottom of the channel directed sheath fluid from the sides to the top and bottom of the channel, completely surrounding the sample stream. Optical fibers inserted into guide channels provided excitation light from diode lasers at 532 and 635 nm and collected the emission wavelengths. Two emission collection fibers were connected to PMTs through a multimode fiber splitter and optical filters for detection at 635 nm (scatter), 665 nm and 700 nm (microsphere identification) and 565 nm (phycoerythrin tracer). The cytometer was capable of discriminating microspheres with different amounts of the fluorophores used for coding and detecting the presence of a phycoerythrin antibody complex on the surface of the microspheres. Assays for Escherichia coli were compared with a commercial Luminex flow cytometer.

Two simple and rugged designs for creating microfluidic sheath flow.

A simple design capable of 2-dimensional hydrodynamic focusing is proposed and successfully demonstrated. In the past, most microfluidic sheath flow systems have often only confined the sample solution on the sides, leaving the top and bottom of the sample stream in contact with the floor and ceiling of the channel. While relatively simple to build, these designs increase the risk of adsorption of sample components to the top and bottom of the channel. A few designs have been successful in completely sheathing the sample stream, but these typically require multiple sheath inputs and several alignment steps. In the designs presented here, full sheathing is accomplished using as few as one sheath input, which eliminates the need to carefully balance the flow of two or more sheath inlets. The design is easily manufactured using current microfabrication techniques. Furthermore, the sample and sheath fluid can be subsequently separated for recapture of the sample fluid or re-use of the sheath fluid. Designs were demonstrated in poly(dimethylsiloxane) (PDMS) using soft lithography and poly(methyl methacrylate) (PMMA) using micromilling and laser ablation.

The good, the bad, and the tiny: a review of microflow cytometry.

Recent developments in microflow cytometry have concentrated on advancing technology in four main areas: (1) focusing the particles to be analyzed in the microfluidic channel, (2) miniaturization of the fluid-handling components, (3) miniaturization of the optics, and (4) integration and applications development. Strategies for focusing particles in a narrow path as they pass through the detection region include the use of focusing fluids, nozzles, and dielectrophoresis. Strategies for optics range from the use of microscope objectives to polymer waveguides or optical fibers embedded on-chip. While most investigators use off-chip fluidic control, there are a few examples of integrated valves and pumps. To date, demonstrations of applications are primarily used to establish that the microflow systems provide data of the same quality as laboratory systems, but new capabilities-such as automated sample staining-are beginning to emerge. Each of these four areas is discussed in detail in terms of the progress of development, the continuing limitations, and potential future directions for microflow cytometers.

Surface modification of silica nanoparticles to reduce aggregation and nonspecific binding.

In this article, a systematic study of the design and development of surface-modification schemes for silica nanoparticles is presented. The nanoparticle surface design involves an optimum balance of the use of inert and active surface functional groups to achieve minimal nanoparticle aggregation and reduce nanoparticle nonspecific binding. Silica nanoparticles were prepared in a water-in-oil microemulsion and subsequently surface modified via cohydrolysis with tetraethyl orthosilicate (TEOS) and various organosilane reagents. Nanoparticles with different functional groups, including carboxylate, amine, amine/phosphonate, poly(ethylene glycol), octadecyl, and carboxylate/octadecyl groups, were produced. Aggregation studies using SEM, dynamic light scattering, and zeta potential analysis indicate that severe aggregation among amine-modified silica nanoparticles can be reduced by adding inert functional groups, such as methyl phosphonate, to the surface. To determine the effect of various surface-modification schemes on nanoparticle nonspecific binding, the interaction between functionalized silica nanoparticles and a DNA chip was also studied using confocal imaging/fluorescence microscopy. Dye-doped silica nanoparticles functionalized with octadecyl and carboxylate groups showed minimal nonspecific binding. Using these surface-modification schemes, fluorescent dye-doped silica nanoparticles can be more readily conjugated with biomolecules and used as highly fluorescent, sensitive, and reproducible labels in bioanalytical applications.

Using bioconjugated nanoparticles to monitor E. coli in a flow channel.

A simple and portable flow channel optical detection system combined with bioconjugated luminescent nanoparticles allows the rapid detection of single bacterial cells without sample enrichment. The optical system is designed to have single-molecule-detection capability in a microcapillary flow channel by decreasing the laser excitation probe volume to a few picoliters, which consequently results in a low background. Specific monoclonal antibodies were immobilized on nanoparticles to form nanoparticle-antibody conjugates. The bioconjugated nanoparticles bind to the target bacteria when they recognize the antigen on the bacterium surface, thus providing a bright luminescent signal for the detection of individual bacteria cells. The high sensitivity provided by the luminescent and photostable silica nanoparticles eliminates the need for further enrichment of bacteria samples and signal amplification. This flow channel detection system is convenient and allows the detection of single bacterial cells within a few minutes.

Outbreak of travel-related pontiac fever among hotel guests illustrating the need for better diagnostic tests.

BACKGROUND: Pontiac fever (PF), a legionellosis with influenza-like symptoms and high attack rates, is rarely reported. Travel-related outbreaks can elude detection because infected persons are often widely removed geographically from the transmission source before illness onset. Thirty-one persons staying at an Illinois hotel during August 9 to 11, 2002, reported influenza-like symptoms to local health departments within 24 to 48 hours of checkout. We investigated to identify the cause and source of illness to guide control measures. METHODS: Hotel water samples were collected for culture. A telephone questionnaire detailing illness symptoms and exposures was administered to all who were guests at the hotel from August 9 to 15 (n = 380). A case was defined as onset of fever, headache, and myalgia in a guest in the 14 days following the hotel stay. Patient sera were tested by hemagglutination assay for antibodies to Legionella species. RESULTS: Among 204 questionnaire respondents from 15 states and Canada, 50 met the case definition. Among persons exposed to the swimming pool/whirlpool spa area, 63% (47 of 75) became ill versus 3% (3 of 110) of unexposed persons (relative risk 23.0, 95% CI 7.4-71.1). Illness risk increased with increasing time exposed to the pool/spa. Approximately 95 to 115 bathers per day, two to three times above the usual number, used the spa during August 9 to 11. Three Legionella species, L. dumoffii, L. maceachernii, and L. micdadei, were isolated from spa filter backwash cultures. Two of 15 ill persons with acute- and convalescent-phase sera had a greater than fourfold rise in antibody titer to L. micdadei. CONCLUSIONS: PF was associated with exposure to a hotel pool/spa area. Heavy bather usage likely contributed to a decreased effectiveness of the disinfectant in the whirlpool spa, possibly promoting bacterial aerosolization. Linking case information from many states is essential in identifying and eliminating the source of disease transmission in travel-related outbreaks of PF. Clinicians should be aware of PF in the differential diagnosis of patients with influenza-like symptoms following recent travel, particularly with exposure to a communal-use whirlpool spa.

A rapid bioassay for single bacterial cell quantitation using bioconjugated nanoparticles.

The rapid and sensitive determination of pathogenic bacteria is extremely important in biotechnology, medical diagnosis, and the current fight against bioterrorism. Current methods either lack ultrasensitivity or take a long time for analysis. Here, we report a bioconjugated nanoparticle-based bioassay for in situ pathogen quantification down to single bacterium within 20 min. The bioconjugated nanoparticle provides an extremely high fluorescent signal for bioanalysis and can be easily incorporated with biorecognition molecules, such as antibody. The antibody-conjugated nanoparticles can readily and specifically identify a variety of bacterium, such as Escherichia coli O157:H7, through antibody-antigen interaction and recognition. The single-bacterium-detection capability within 20 min has been confirmed by the plate-counting method and realized by using two independent optical techniques. The two detection methods correlated extremely well. Furthermore, we were able to detect multiple bacterial samples with high throughput by using a 384-well microplate format. To show the usefulness of this assay, we have accurately detected 1-400 E. coli O157 bacterial cells in spiked ground beef samples. Our results demonstrate the potential for a broad application of bioconjugated nanoparticles in practical biotechnological and medical applications in various biodetection systems. The ultimate power of integrating bionanotechnology into complex biological systems will emerge as a revolutionary tool for ultrasensitive detection of disease markers and infectious agents.

Optimization of dye-doped silica nanoparticles prepared using a reverse microemulsion method.

Fluorescent labeling based on silica nanoparticles facilitates unique applications in bioanalysis and bioseparation. Dye-doped silica nanoparticles have significant advantages over single-dye labeling in signal amplification, photostability and surface modification for various biological applications. We have studied the formation of tris(2,2'-bipyridyl)dichlororuthenium(II) (Ru(bpy)) dye-doped silica nanoparticles by ammonia-catalyzed hydrolysis of tetraethyl orthosilicate (TEOS) in water-in-oil microemulsion. The fluorescence spectra, particle size, and size distribution of Ru(bpy) dye-doped silica nanoparticles were examined as a function of reactant concentrations (TEOS and ammonium hydroxide), nature of surfactant molecules, and molar ratios of water to surfactant (R) and cosurfactant to surfactant (p). The particle size and fluorescence spectra were dependent upon the type of microemulsion system chosen. The particle size was found to decrease with an increase in concentration of ammonium hydroxide and increase in water to surfactant molar ratio (R) and cosurfactant to surfactant molar ratio (p). This optimization study of the preparation of dye-doped silica nanoparticles provides a fundamental knowledge of the synthesis and optical properties of Ru(bpy) dye-doped silica nanoparticles. With this information, these nanoparticles can be easily manipulated, with regard to particle size and size distribution, and bioconjugated as needed for bioanalysis and bioseparation applications.