4,223 research outputs found
Resource ecology of the Bolinao coral reef system
Resource /Energy Economics and Policy,
Intrinsic flexibility of snRNA hairpin loops facilitates protein binding
Stem–loop II of U1 snRNA and Stem–loop IV of U2 snRNA typically have 10 or 11 nucleotides in their loops. The fluorescent nucleobase 2-aminopurine was used as a substitute for the adenines in each loop to probe the local and global structures and dynamics of these unusually long loops. Using steady-state and time-resolved fluorescence, we find that, while the bases in the loops are stacked, they are able to undergo significant local motion on the picosecond/nanosecond timescale. In addition, the loops have a global conformational change at low temperatures that occurs on the microsecond timescale, as determined using laser T-jump experiments. Nucleobase and loop motions are present at temperatures far below the melting temperature of the hairpin stem, which may facilitate the conformational change required for specific protein binding to these RNA loops
Age-related differences in dual task walking: a cross sectional study
<p>Abstract</p> <p>Background</p> <p>Variability in stride velocity during walking characterizes gait instability and predicts falling in older individuals. Walking while executing a cognitive task is also associated with increased risk of falling, particularly in older adults. Variability in stride velocity, particularly during dual task walking conditions, may differ between younger and older individuals. The purpose of this study was to examine whether gait velocity and variability in stride velocity differ between older community-dwelling women and younger women during dual task walking.</p> <p>Methods</p> <p>Twenty-three older (80 ± 9 years) and 19 younger (23 ± 2 years) women walked under each of two conditions: (1) walking at a self-selected velocity and (2) walking at a self-selected velocity while incrementally counting backwards. Gait velocity and variability in stride velocity were measured with GAITRite<sup>® </sup>instrumentation.</p> <p>Results</p> <p>Gait velocity decreased and variability in stride variability increased, in both groups, during dual task walking. The relative reduction in gait velocity and the magnitude of variability in stride velocity were greater in the older subjects than younger subjects.</p> <p>Conclusion</p> <p>The gait changes observed in dual task walking characterize reduced gait stability and indicate that cognitively demanding tasks during walking have a destabilizing effect on gait that may place older persons at greater risk of falls.</p
Are there multiple kinds of episodic memory? An fMRI investigation comparing autobiographical and recognition memory tasks
What brain regions underlie retrieval from episodic memory? The bulk of research addressing this question with fMRI has relied upon recognition memory for materials encoded within the laboratory. Another, less dominant tradition has used autobiographical methods, whereby people recall events from their lifetime, often after being cued with words or pictures. The current study addresses how the neural substrates of successful memory retrieval differed as a function of the targeted memory when the experimental parameters were held constant in the two conditions (except for instructions). Human participants studied a set of scenes and then took two types of memory test while undergoing fMRI scanning. In one condition (the picture memory test), participants reported for each scene (32 studied, 64 nonstudied) whether it was recollected from the prior study episode. In a second condition (the life memory test), participants reported for each scene (32 studied, 64 nonstudied) whether it reminded them of a specific event from their preexperimental lifetime. An examination of successful retrieval (yes responses) for recently studied scenes for the two test types revealed pronounced differences; that is, autobiographical retrieval instantiated with the life memory test preferentially activated the default mode network, whereas hits in the picture memory test preferentially engaged the parietal memory network as well as portions of the frontoparietal control network. When experimental cueing parameters are held constant, the neural underpinnings of successful memory retrieval differ when remembering life events and recently learned events
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Lanreotide extended-release aqueous-gel formulation, injected by patient, partner or healthcare provider in patients with acromegaly in the United States: 1-year data from the SODA registry
Lanreotide depot (LD; commercial name Somatuline® Depot) is an injectable, extended-release formulation of the synthetic somatostatin analog (SSA) lanreotide. In recent clinical trials, LD was found to be suitable for self or partner administration, avoiding the need to travel to a medical facility. The Somatuline® Depot for Acromegaly (SODA) study is an ongoing, multicenter, observational study in the US investigating the efficacy, safety, convenience and symptom relief provided by LD in patients with acromegaly. Sub-analyses explore outcomes according to who administered the injection: patient, partner, healthcare provider (HCP) or a combination. Data reported here reflect one year of patient experience. Patients are eligible for inclusion if they have a diagnosis of acromegaly, are treated with LD and can give signed informed consent. Baseline data include patient demographics, previous acromegaly treatment and investigations, GH and IGF-I levels, LD dose and dose adjustment frequency. Symptom frequency, injection pain and treatment convenience are assessed using patient-reported questionnaires. As of 18 April 2012, 166 patients had enrolled in SODA. Most (72 %) achieved normal IGF-I levels after 12 months of LD treatment. Disease control was similar in self or partner injectors and in patients who received injections from their HCP, although self or partner injecting was deemed more convenient. LD was well-tolerated irrespective of who performed the injection. Self injection led to more injection-site reactions, but this did not increase the rate of treatment interruption. Acromegaly symptoms remained stable. Biochemical, safety and convenience data support the clinical validity of injecting LD at home
Application of Emulsified Zero-Valent Iron to Marine Environments
Contamination of marine waters and sediments with heavy metals and dense non-aqueous phase liquids (DNAPLs) including chlorinated solvents, pesticides and PCBs pose ecological and human health risks through the contaminant's potential bioaccumulation in fish, shellfish and avian populations. The contaminants enter marine environments through improper disposal techniques and storm water run-off. Current remediation technologies for application to marine environments include costly dredging and off-site treatment of the contaminated media. Emulsified zero-valent iron (EZVI) has been proven to effectively degrade dissolved-phase and DNAPL-phase contaminants in freshwater environments on both the laboratory and field-scale level. However, the application to marine environments is only just being explored. This paper discusses the potential use of EZVI in brackish and saltwater environments, with supporting laboratory data detailed. Laboratory studies were performed in 2005 to establish the effectiveness of EZVI to degrade trichloroethylene (TCE) in saltwater. Headspace vials were setup to determine the kinetic rate of TCE degradation using EZVI in seawater. The reaction vials were analyzed by Gas Chromatographic/Flame Ionization Detection (GC/FID) for ethene production after a 48 day period using a GC/FID Purge and Trap system. Analytical results showed that EZVI was very effective at degrading TCE. The reaction by-products (ethene, acetylene and ethane) were produced at 71% of the rate in seawater as in the fresh water controls. Additionally, iron within the EZVI particles was protected from oxidation of the corrosive seawater, allowing EZVI to perform in an environment where zero-valent iron alone could not compete. Laboratory studies were also performed to establish the effectiveness of emulsified zero-valent metal (EZVM) to remove dissolved-phase cadmium and lead found in seawater. EZVM is comprised of a combination of magnesium and iron metal surrounded by the same oil/surfactant membrane used in EZVI. The removal of cadmium and lead from a seawater matrix is a unique challenge. It requires a system that is resistant to the corrosive nature of seawater while removing specific ions that are in a relatively low concentration compared to naturally occurring seawater salts. Laboratory studies conducted show greater than 99% removal of lead and 96% removal of cadmium from a seawater solution spiked at 5 mg/L that was treated with an Emulsified Zero-Valent Metal (EZVM). The cadmium and lead are removed from the solution as they transport across the emulsion membrane and plate out onto the zero-valent metal surface
In-Depth Analysis of Evaluation Practices and Criteria for Competency-Based Aviation Training Models
NPS NRP Executive SummaryThis work will examine current training standards, necessary learning methodology, and evaluate emergent technologies to make recommendations for future training management.N9 - Warfare SystemsThis research is supported by funding from the Naval Postgraduate School, Naval Research Program (PE 0605853N/2098). https://nps.edu/nrpChief of Naval Operations (CNO)Approved for public release. Distribution is unlimited.
Application of Emulsified Zero-Valent Iron to Marine Environments
Contamination of marine waters and sediments with heavy metals and dense non-aqueous phase liquids (DNAPLs) including chlorinated solvents, pesticides and PCBs pose ecological and human health risks through the potential of the contaminant to bioaccumulate in fish, shellfish and avian populations. The contaminants enter marine environments through improper disposal techniques and storm water runoff. Current remediation technologies for application to marine environments include costly dredging and off-site treatment of the contaminated media. Emulsified zero-valent iron (EZVI) has been proven to effectively degrade dissolved-phase and DNAPL-phase contaminants in freshwater environments on both the laboratory and field-scale level. Emulsified Zero-Valent Metal (EZVM) using metals such as iron and/or magnesium have been shown in the laboratory and on the bench scale to be effective at removing metals contamination in freshwater environments. The application to marine environments, however, is only just being explored. This paper discusses. the potential use of EZVI or EZVM in brackish and saltwater environments, with supporting laboratory data detailing its effectiveness on trichloroethylene, lead, copper, nickel and cadmium
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