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Search Results: 1 - 10 of 95624 matches for " Rachel I. Anderson "
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Orexin-1 and orexin-2 receptor antagonists reduce ethanol self-administration in high-drinking rodent models
Rachel I. Anderson,Howard C. Becker,Benjamin L. Adams,Linda M. Rorick-Kehn
Frontiers in Neuroscience , 2014, DOI: 10.3389/fnins.2014.00033
Abstract: To examine the role of orexin-1 and orexin-2 receptor activity on ethanol self-administration, compounds that differentially target orexin (OX) receptor subtypes were assessed in various self-administration paradigms using high-drinking rodent models. Effects of the OX1 antagonist SB334867, the OX2 antagonist LSN2424100, and the mixed OX1/2 antagonist almorexant (ACT-078573) on home cage ethanol consumption were tested in ethanol-preferring (P) rats using a 2-bottle choice procedure. In separate experiments, effects of SB334867, LSN2424100, and almorexant on operant ethanol self-administration were assessed in P rats maintained on a progressive ratio operant schedule of reinforcement. In a third series of experiments, SB334867, LSN2424100, and almorexant were administered to ethanol-preferring C57BL/6J mice to examine effects of OX receptor blockade on ethanol intake in a binge-like drinking (drinking-in-the-dark) model. In P rats with chronic home cage free-choice ethanol access, SB334867 and almorexant significantly reduced ethanol intake, but almorexant also reduced water intake, suggesting non-specific effects on consummatory behavior. In the progressive ratio operant experiments, LSN2424100 and almorexant reduced breakpoints and ethanol consumption in P rats, whereas the almorexant inactive enantiomer and SB334867 did not significantly affect the motivation to consume ethanol. As expected, vehicle-injected mice exhibited binge-like drinking patterns in the drinking-in-the-dark model. All three OX antagonists reduced both ethanol intake and resulting blood ethanol concentrations relative to vehicle-injected controls, but SB334867 and LSN2424100 also reduced sucrose consumption in a different cohort of mice, suggesting non-specific effects. Collectively, these results contribute to a growing body of evidence indicating that OX1 and OX2 receptor activity influences ethanol self-administration, although the effects may not be selective for ethanol consumption.
Competition of Squirreltail with Cheatgrass at Three Nitrogen Levels  [PDF]
Allan R. Stevens, Val Jo Anderson, Rachel Fugal
American Journal of Plant Sciences (AJPS) , 2014, DOI: 10.4236/ajps.2014.57112
Abstract:

Squirreltail (Elymus elymoides [Raf] Swezey) can grow in cheatgrass (Bromus tectorum L.) stands, and has reduced the biomass production of cheatgrass in its immediate vicinity. A field experiment was conducted to determine: 1) if competition for nitrogen resources occurs between seedlings of squirreltail and seedlings of cheatgrass, under low, medium, and high nitrogen levels, and; 2) if competition for nitrogen resources in the seedling stage is a mechanism that allows squirreltail to establish in cheatgrass stands. Five accessions of squirreltail were each seeded with a single accession of cheatgrass in a cultivated field near Ephraim, Utah in the fall of 1995 and again in 1996. A completely randomized strip-plot design with 3 replications was used including the 5 joint seedings as well as pure seedings of each accession of both species. Three nitrogen levels representing high, medium (control), and low were applied. The study was replicated over 2 years in different areas of the same field. Harvests of above-ground biomass of squirreltail and cheatgrass within each treatment were conducted in July of 1996 and 1997. Using biomass production as a measure of efficient nitrogen use, cheatgrass competed for and used nitrogen resources more efficiently than squirreltail when nitrogen was not limiting. All squirreltail accessions were able to compete for and use nitrogen more efficiently than cheatgrass when there was low availability of nitrogen. Some accessions of squirreltail competed for nitrogen resources more efficiently than others both in the control and at the reduced nitrogen level. White Rocks and Sublette squirreltail accessions were the best competitors with cheatgrass at the low nitrogen level reducing the cheatgrasss biomass by as much as 75% and 67% respectively. An intermediate competitor with cheatgrass was the Gunnison accession. The Washakie and Pueblo accessions were poor competitors with cheatgrass at low nitrogen levels.

Behavioral and Immune Responses to Infection Require Gαq- RhoA Signaling in C. elegans
Rachel McMullan ,Alexandra Anderson,Stephen Nurrish
PLOS Pathogens , 2012, DOI: 10.1371/journal.ppat.1002530
Abstract: Following pathogen infection the hosts' nervous and immune systems react with coordinated responses to the danger. A key question is how the neuronal and immune responses to pathogens are coordinated, are there common signaling pathways used by both responses? Using C. elegans we show that infection by pathogenic strains of M. nematophilum, but not exposure to avirulent strains, triggers behavioral and immune responses both of which require a conserved Gαq-RhoGEF Trio-Rho signaling pathway. Upon infection signaling by the Gαq pathway within cholinergic motorneurons is necessary and sufficient to increase release of the neurotransmitter acetylcholine and increase locomotion rates and these behavioral changes result in C. elegans leaving lawns of M. nematophilum. In the immune response to infection signaling by the Gαq pathway within rectal epithelial cells is necessary and sufficient to cause changes in cell morphology resulting in tail swelling that limits the infection. These Gαq mediated behavioral and immune responses to infection are separate, act in a cell autonomous fashion and activation of this pathway in the appropriate cells can trigger these responses in the absence of infection. Within the rectal epithelium the Gαq signaling pathway cooperates with a Ras signaling pathway to activate a Raf-ERK-MAPK pathway to trigger the cell morphology changes, whereas in motorneurons Gαq signaling triggers behavioral responses independent of Ras signaling. Thus, a conserved Gαq pathway cooperates with cell specific factors in the nervous and immune systems to produce appropriate responses to pathogen. Thus, our data suggests that ligands for Gq coupled receptors are likely to be part of the signals generated in response to M. nematophilum infection.
Optimal Cosmic-Ray Detection for Nondestructive Read Ramps
Rachel E. Anderson,Karl D. Gordon
Physics , 2011, DOI: 10.1086/662593
Abstract: Cosmic rays are a known problem in astronomy, causing both loss of data and data inaccuracy. The problem becomes even more extreme when considering data from a high-radiation environment, such as in orbit around Earth or outside the Earth's magnetic field altogether, unprotected, as will be the case for the James Webb Space Telescope (JWST). For JWST, all the instruments employ nondestructive readout schemes. The most common of these will be "up the ramp" sampling, where the detector is read out regularly during the ramp. We study three methods to correct for cosmic rays in these ramps: a two-point difference method, a deviation from the fit method, and a y-intercept method. We apply these methods to simulated nondestructive read ramps with single-sample groups and varying combinations of flux, number of samples, number of cosmic rays, cosmic-ray location in the exposure, and cosmic-ray strength. We show that the y-intercept method is the optimal detection method in the read-noise-dominated regime, while both the y-intercept method and the two-point difference method are best in the photon-noise-dominated regime, with the latter requiring fewer computations.
Grip Force Using an Artificial Limb in a Congenital Amputee  [PDF]
Michael Trujillo, David I. Anderson, Marilyn Mitchell
Open Journal of Therapy and Rehabilitation (OJTR) , 2014, DOI: 10.4236/ojtr.2014.23014
Abstract: While much attention is being given in the application of advanced technologies to improve upper extremity prostheses, traditional body-powered prostheses still remain the most popular by people with an amputation. A body-powered prosthesis provides the user with a reasonable solution for limb loss given their simple design, lower maintenance and initial cost. The two major types of body-powered prosthesis use either voluntary opening or voluntary closing control of the terminal device (or prehensor) used for holding and manipulating objects. What differentiates these two types of control is the relationship between the muscular force used to apply tension on the cable attached to the prehensor and the force produced by the prehensor. It has been argued that the voluntary closing prosthesis has more optimal compatibility between the muscle force and grip force of the prehensor. As a result, it may provide an advantage to the user in tasks requiring the control of grip force. To determine the effectiveness of the voluntary closing and voluntary opening prosthesis, we asked a person with a congenital quadruple limb deficiency who is right hand dominant, and that uses voluntary opening prostheses to participate in a study investigating grip force control. The participant was required to match different target grip forces displayed on a computer monitor by manipulating the pressure exerted on a hand dynamometer using either a voluntary closing or voluntary opening prosthesis. The participant only had previous experience with a voluntary opening prosthesis. The results showed that in several measures, the participant performed better with the voluntary closing prosthesis. These results provided support for the muscular force-grip force compatibility hypothesis.
Comparison of the ICRP 60 and ICRP 103 Recommendations on the Determination of the Effective Dose from Abdominopelvic Computed Tomography  [PDF]
Rachel I. Obed, Godwin Inalegwu Ogbole, Samson Babatunde Majolagbe
International Journal of Medical Physics,Clinical Engineering and Radiation Oncology (IJMPCERO) , 2015, DOI: 10.4236/ijmpcero.2015.42021
Abstract:
The effective dose takes into consideration the amount of absorbed dose received by tissues, individual organs and also organ’s radiosensitivity. This study concentrates on the Commission’s regulations of 1991 and 2007 tagged ICRP 60 and ICRP 103 respectively, and seeks to suggest the better guideline for determination of detriment to patient especially from abdominopelvic computed tomography. With mean totals of 375.0 mSv for the ICRP 60 and 341.3 mSv for the ICRP 103 obtained from abdominopelvic computed tomography involving 20 different patients, a T-test calculated value of 6.716 was obtained and compared with the value in the T-table at 95% confidence limit and 18 degrees of freedom to confirm whether there is a significant difference in both ICRP 60 and 103 recommendations in the determination of the effective dose. Finally, it is concluded that there is a significant difference in the ICRP 60 and ICRP 103 as fewer effective doses are obtained from the ICRP 103 recommendations and this difference verifies that the ICRP 103 is more suitable for the determination of the effective dose.
Freak waves of different types in the coastal zone of the Baltic Sea
I. Didenkulova,C. Anderson
Natural Hazards and Earth System Sciences (NHESS) & Discussions (NHESSD) , 2010, DOI: 10.5194/nhess-10-2021-2010
Abstract: We present a statistical analysis of freak waves1 measured during the 203 h of observation on sea surface elevation at a location in the coastal zone of the Baltic Sea (2.7 m depth) during June–July 2008. The dataset contains 97 freak waves occurring in both calm and stormy weather conditions. All of the freak waves are solitary waves, 63% of them having positive shape, 17.5% negative shape and 19.5% sign-variable shape. It is suggested that the freak waves can be divided into two groups. Those of the first group, which includes 92% of the freak waves, have an amplification factor (ratio of freak wave height to significant wave height) which does not vary from significant wave height and has values largely within the range of 2.0 to 2.4; while for the second group, which contain the most extreme freak waves, amplification factors depend strongly on significant wave height and can reach 3.1. Analysis based on the Generalised Pareto distribution is used to describe the waves of the first group and lends weight to the identification of the two groups. It is suggested that the probable mechanism of the generation of freak waves in the second group is dispersive focussing. The time-frequency spectra of the freak waves are studied and dispersive tracks, which can be interpreted as dispersive focussing, are demonstrated. 1 taken to be waves whose height is 2 or more times greater than the significant wave height
Tuning in on Cepheids: Radial velocity amplitude modulations. A source of systematic uncertainty for Baade-Wesselink distances
Richard I. Anderson
Physics , 2014, DOI: 10.1051/0004-6361/201423850
Abstract: [Abridged] I report the discovery of modulations in radial velocity (RV) curves of four Galactic classical Cepheids and investigate their impact as a systematic uncertainty for Baade-Wesselink distances. Highly precise Doppler measurements were obtained using the Coralie high-resolution spectrograph since 2011. Particular care was taken to sample all phase points in order to very accurately trace the RV curve during multiple epochs and to search for differences in linear radius variations derived from observations obtained at different epochs. Different timescales are sampled, ranging from cycle-to-cycle to months and years. The unprecedented combination of excellent phase coverage obtained during multiple epochs and high precision enabled the discovery of significant modulation in the RV curves of the short-period s-Cepheids QZ Normae and V335 Puppis, as well as the long-period fundamental mode Cepheids l Carinae and RS Puppis. The modulations manifest as shape and amplitude variations that vary smoothly on timescales of years for short-period Cepheids and from one pulsation cycle to the next in the long-period Cepheids. The order of magnitude of the effect ranges from several hundred m/s to a few km/s. The resulting difference among linear radius variations derived using data from different epochs can lead to systematic errors of up to 15% for Baade-Wesselink-type distances, if the employed angular and linear radius variations are not determined contemporaneously. The different natures of the Cepheids exhibiting modulation in their RV curves suggests that this phenomenon is common. The observational baseline is not yet sufficient to conclude whether these modulations are periodic. To ensure the accuracy of Baade-Wesselink distances, angular and linear radius variations should always be determined contemporaneously.
Amplitude Modulation of Cepheid Radial Velocity Curves as a Systematic Source of Uncertainty for Baade-Wesselink Distances
Richard I. Anderson
Physics , 2014, DOI: 10.1017/S1743921314006942
Abstract: I report on the recent discovery of modulation in the radial velocity curves in four classical Cepheids. This discovery may enable significant improvements in the accuracy of Baade-Wesselink distances by revealing a not previously considered systematic source of uncertainty.
New Zealand parent′s perceptions of the use and safety of over the counter liquid analgesics
Bushby,Sarah K.; Anderson,Rachel J.; Braund,Rhiannon;
Pharmacy Practice (Internet) , 2010, DOI: 10.4321/S1886-36552010000400006
Abstract: objective: the objective of this study was to investigate the knowledge of parents and caregivers with respect to the purchase, use and storage of liquid analgesics purchased over the counter (otc) from pharmacies. this would enable specific strategies to be identified to increase awareness of the potential risks of these products. methods: questionnaires were developed and used a combination of likert scales, open ended questions and yes/no answers. randomly chosen new zealand pharmacies (463) were asked to approach a person purchasing liquid analgesics and ask them to complete the questionnaire. of the 105 pharmacies that participated, 96 completed parent/caregiver questionnaires were returned. results: when choosing a product there was a statistically significant difference between the most important factors "safety" and "active ingredient" and the least important factors "cost" and if the parent/caregiver "used it before". all parents/caregivers claim to have received verbal information from pharmacy staff, with 40% stating that they "always" receive information. the majority of parents/caregivers store medicines in a high place (n=61), in a cupboard (n=56) or a combination of these. over half (52%) of the parents/caregivers thought that children could "never" open child resistant closures. conclusion: whilst parents and caregivers choose products based on perceived safety, there is an over estimation in the perception of the protection that a child resistant closure actually offers. the general public needs to continually be vigilant in the use, storage and administration when using medication in the vicinity of children.
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