17,375 research outputs found
Diapause in the Boll Weevil, Anthonontus grandis Boheman, As Related to Fruiting Activity in the Cotton Plant
Studies in Arkansas show that boll weevil diapause is related to changes in fruiting activity of the cotton plant. Generally, when larval development took place while fruiting levels were increasing or being held at a high level, diapause in resulting adults was low (0-20%). Diapause was approximately 20-50% when larval development coincided with decreasing fruiting levels, and was 50-100% as true cut-out approached. Regrowth cotton generally lowered diapause incidence and as fruiting levels decreased, diapause increased. Therefore, the boll weevil not only responds to short photoperiods that are characteristic during the fall in the temperate zone, but also may respond throughout the season to changes in fruiting activity of the cotton plant
A Portable, Low-Cost Wheelchair Ergometer Design Based on a Mathematical Model of Pediatric Wheelchair Dynamics
Evaluation and training of wheelchair propulsion improves efficiency and prevents orthopaedic injury in pediatric manual wheelchair users. Ergometers allow static propulsion and emulate typical conditions. Currently available ergometers have deficiencies that limit their use in motion analysis. A new ergometer is developed and evaluated based on a model of wheelchair inertial dynamics that eliminates these deficiencies. This makes integrated motion analysis of wheelchair propulsion in current community, home, and international outreach efforts possible
A Quantitative Sequencing Framework for Absolute Abundance Measurements of Mucosal and Lumenal Microbial Communities
A fundamental goal in microbiome studies is determining which microbes affect host physiology. Standard methods for determining changes in microbial taxa measure relative, rather than absolute abundances. Moreover, studies often analyze only stool, despite microbial diversity differing substantially among gastrointestinal (GI) locations. Here, we develop a quantitative framework to measure absolute abundances of individual bacterial taxa by combining the precision of digital PCR with the high-throughput nature of 16S rRNA gene amplicon sequencing. In a murine ketogenic-diet study, we compare microbial loads in lumenal and mucosal samples along the GI tract. Quantitative measurements of absolute (but not relative) abundances reveal decreases in total microbial loads on the ketogenic diet and enable us to determine the differential effects of diet on each taxon in stool and small-intestine mucosa samples. This rigorous quantitative microbial analysis framework, appropriate for diverse GI locations enables mapping microbial biogeography of the mammalian GI tract and more accurate analyses of changes in microbial taxa in microbiome studies
Evaluation of Upper Extremity Movement Characteristics during Standardized Pediatric Functional Assessment with a Kinect®-based Markerless Motion Analysis System
A recently developed and evaluated upper extremity (UE) markerless motion analysis system based on the Microsoft® Kinect® has potential for improving functional assessment of patients with hemiplegic cerebral palsy. 12 typically-developing adolescents ages 12-17 were evaluated using both the Kinect-based system and the Shriners Hospitals for Children Upper Extremity Evaluation (SHUEE), a validated measure of UE motion. The study established population means of UE kinematic parameters for each activity. Statistical correlation analysis was used to identify key kinematic metrics used to develop automatic scoring algorithms. The Kinect motion analysis platform is technically sound and can be applied to standardized task-based UE evaluation while providing enhanced sensitivity in clinical analysis and automation through scoring algorithms
Generation of maximally entangled states with sub-luminal Lorentz boost
Recent work has studied entanglement between the spin and momentum components
of a single spin-1/2 particle and showed that maximal entanglement is obtained
only when boosts approach the speed of light. Here we extend the boost scenario
to general geometries and show that, intriguingly, maximal entanglement can be
achieved with boosts less than the speed of light. Boosts approaching the speed
of light may even decrease entanglement. We also provide a geometric
explanation for this behavior
Rituximab induced pulmonary edema managed with extracorporeal life support
Though rare, rituximab has been reported to induce severe pulmonary edema. We describe the first report of ECLS utilization for this indication. A 31-year-old female with severe thrombotic thrombocytopenic purpura developed florid pulmonary edema after rituximab infusion. Despite advanced ventilatory settings, she developed severe respiratory acidosis and remained hypoxemic with a significant vasopressor requirement. Since her pulmonary insult was likely transient, ECLS was considered. Due to combined cardiorespiratory failure, she received support with peripheral venoarterial ECLS. During her ECLS course, she received daily plasmapheresis and high dose steroids. Her pulmonary function recovered and she was decannulated after 8 days. She was discharged after 23 days without residual sequelae
Coherent transport in graphene nanoconstrictions
We study the effect of a structural nanoconstriction on the coherent
transport properties of otherwise ideal zig-zag-edged infinitely long graphene
ribbons. The electronic structure is calculated with the standard one-orbital
tight-binding model and the linear conductance is obtained using the Landauer
formula. We find that, since the zero-bias current is carried in the bulk of
the ribbon, this is very robust with respect to a variety of constriction
geometries and edge defects. In contrast, the curve of zero-bias conductance
versus gate voltage departs from the staircase of the ideal case
as soon as a single atom is removed from the sample. We also find that
wedge-shaped constrictions can present non-conducting states fully localized in
the constriction close to the Fermi energy. The interest of these localized
states in regards the formation of quantum dots in graphene is discussed.Comment: 9 pages, 9 figure
Fluorescent species of 7-azaindole and 7-azatryptophan in water
A study of the fluorescence lifetimes and quantum yields of 7-azaindole and its methylated derivatives NImethyl- Famindole (1 M7AI) and 7-methyl-7H-pyrrolo[ 2,341 pyridine (7M7AI) in water is performed in order to explain the observation that the fluorescence spectrum of 7-azaindole apparently consists of one band (A, = 386 nm) whereas in alcohols the spectrum is bimodal (e.g., for methanol, A,, = 374, 505 nm). Careful measurements of the fluorescence decay as a function of emission wavelength indicate a small amplitude of an -70-ps decaying component at the bluer wavelengths and a rising component of the same duration at the redder wavelengths. The small amplitude component, which comprises no more than 20% of the fluorescence decay, is attributed to excited-state tautomerization that is mediated by the solvent. Particular attention is paid to the pH dependence of the fluorescence lifetimes and yields. We propose that upon tautomerization the basic l-nitrogen (NIo)f 7-azaindole is rapidly protonated givingrise to a species whose emission maximum is at -440 nm. The fluorescence emission maximum and lifetime of 7-azaindole is dominated by the 80% of the solute molecules that are blocked by unfavorable solvation from executing excited-state tautomerization. It is proposed that 210 ns is required for the surrounding water molecules to attain a configuration about 7-azaindole that is propitious for tautomerization
A Conductometric Study of the Reaction Velocity of Halodinitrobenzene with Piperidine
The rates of reaction for 1-chloro-, 1-bromo-, and l-iodo-2,4-dinitrobenzene and piperidine in 95% ethanol were determined for various concentrations and temperatures by a conductometric process. An RC-18 Conductivity Bridge with an oscilloscope detector was found to be very satisfactory in the study. The specific rate constants gave the halogen reaction series Cl \u3e Br \u3e\u3e I at all temperatures and concentrations used. The conductometric method for determining reaction velocities has shown itself to be very effective since it allows continuous monitoring of the system thereby eliminating the necessity of a chemical analysis
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