329 research outputs found
Phytochemistry Predicts Habitat Selection by an Avian Herbivore at Multiple Spatial Scales
Animal habitat selection is a process that functions at multiple, hierarchically structured spatial scales. Thus multi-scale analyses should be the basis for inferences about factors driving the habitat selection process. Vertebrate herbivores forage selectively on the basis of phytochemistry, but few studies have investigated the influence of selective foraging (i.e., fine-scale habitat selection) on habitat selection at larger scales. We tested the hypothesis that phytochemistry is integral to the habitat selection process for vertebrate herbivores. We predicted that habitats selected at three spatial scales would be characterized by higher nutrient concentrations and lower concentrations of plant secondary metabolites (PSMs) than unused habitats. We used the Greater Sage-Grouse (Centrocercus urophasianus), an avian herbivore with a seasonally specialized diet of sagebrush, to test our hypothesis. Sage-Grouse selected a habitat type (black sagebrush, Artemisia nova) with lower PSM concentrations than the alternative (Wyoming big sagebrush, A. tridentata wyomingensis). Within black sagebrush habitat, Sage-Grouse selected patches and individual plants within those patches that were higher in nutrient concentrations and lower in PSM concentrations than those not used. Our results provide the first evidence for multi-scale habitat selection by an avian herbivore on the basis of phytochemistry, and they suggest that phytochemistry may be a fundamental driver of habitat selection for vertebrate herbivores
A Distinct Class of Slow ( approximately 0.2-2 Hz) Intrinsically Bursting Layer 5 Pyramidal Neurons Determines UP/DOWN State Dynamics in the Neocortex
During sleep and anesthesia, neocortical neurons exhibit rhythmic UP/DOWN membrane potential states. Although UP states are maintained by synaptic activity, the mechanisms that underlie the initiation and robust rhythmicity of UP states are unknown. Using a physiologically validated model of UP/DOWN state generation in mouse neocortical slices whereby the cholinergic tone present in vivo is reinstated, we show that the regular initiation of UP states is driven by an electrophysiologically distinct subset of morphologically identified layer 5 neurons, which exhibit intrinsic rhythmic low-frequency burst firing at approximately 0.2-2 Hz. This low-frequency bursting is resistant to block of glutamatergic and GABAergic transmission but is absent when slices are maintained in a low Ca(2+) medium (an alternative, widely used model of cortical UP/DOWN states), thus explaining the lack of rhythmic UP states and abnormally prolonged DOWN states in this condition. We also characterized the activity of various other pyramidal and nonpyramidal neurons during UP/DOWN states and found that an electrophysiologically distinct subset of layer 5 regular spiking pyramidal neurons fires earlier during the onset of network oscillations compared with all other types of neurons recorded. This study, therefore, identifies an important role for cell-type-specific neuronal activity in driving neocortical UP states
Recommended from our members
A meta-analysis of greater sage-grouse Centrocercus urophasianus nesting and brood rearing habitat
The distribution and range of the greater sage-grouse Centrocercus urophasianus have been reduced by 56% since the European settlement of western North America. Although there is an unprecedented effort to conserve the species, there is still considerable debate about the vegetation composition and structure required for nesting and brood-rearing habitat. We conducted a meta-analysis of vegetation characteristics recorded in studies at nest sites (N  =  24) and brood habitats (N  =  8) to determine if there was an overall effect (Hedge's d) of habitat selection and to estimate average canopy cover of sagebrush Artemisia spp., grass and forbs, and also height of grass at nest sites and brood-rearing areas. We estimated effect sizes from the difference between use (nests and brood areas) and random sampling points for each study, and derived an overall effect size across all studies. Sagebrush cover (d₊₊  =  0.39; 95% C.I.: 0.19-0.54) and grass height (d₊₊ =  0.28; 95% C.I.: 0.13-0.42) were greater at nest sites than at random locations. Vegetation at brood areas had less sagebrush cover (d₊₊  =  -0.17; 95% C.I.: -0.44 - +0.18), significantly taller grasses (d₊₊  =  0.31; 95% C.I.: 0.14-0.45), greater forb (d₊₊  =  0.48; 95% C.I.: 0.30-0.67) and grass cover (d₊₊ =  0.17; 95% C.I.: 0.08-0.27) than at random locations. These patterns were especially evident when we examined early (< 6 weeks post hatching) and late brood-rearing habitats separately. The overall estimates of nest and brood area vegetation variables were consistent with those provided in published guidelines for the management of greater sage-grouse.Keywords: sagebrush,
breeding habitat,
effect size,
greater sage-grouse,
Artemisia spp.,
Hedges’ d,
meta-analysi
161. The Potential Role of Extensor Muscle Fatigue in the Onset of Intervertebral Disc Degeneration: A Novel In Vivo Model
BACKGROUND CONTEXT: Occupation is strongly correlated to low back pain (LBP). Specific occupational activities associated with low back pain include poor posture, whole body vibration, and repetitive lifting. These activities have a common link: they result in fatigue of the primary spinal extensor musculature. This fatigue may lead to increased intervertebral loading - a stimulus for disc degeneration. If true, this association could provide a vital connection between detrimental physical activities and LBP. However, the link between muscle fatigue and increased load across the disc space has never been quantified in vivo.
PURPOSE: The purpose of this study was to develop and test a wireless multi-axial force-sensing implant and large animal model of primary extensor muscle fatigue. Combined, these tools allow measurement of in vivo spinal forces during muscle fatigue to quantify changes in spine loading
Design Specification for a Thrust-Vectoring, Actuated-Nose-Strake Flight Control Law for the High-Alpha Research Vehicle
Specifications for a flight control law are delineated in sufficient detail to support coding the control law in flight software. This control law was designed for implementation and flight test on the High-Alpha Research Vehicle (HARV), which is an F/A-18 aircraft modified to include an experimental multi-axis thrust-vectoring system and actuated nose strakes for enhanced rolling (ANSER). The control law, known as the HARV ANSER Control Law, was designed to utilize a blend of conventional aerodynamic control effectors, thrust vectoring, and actuated nose strakes to provide increased agility and good handling qualities throughout the HARV flight envelope, including angles of attack up to 70 degrees
Clonal Growth of Dermal Papilla Cells in Hydrogels Reveals Intrinsic Differences between Sox2-Positive and -Negative Cells In Vitro and In Vivo
In neonatal mouse skin, two types of dermal papilla (DP) are distinguished by Sox2 expression: CD133+Sox2+ DP are associated with guard/awl/auchene hairs, whereas CD133+Sox2− DP are associated with zigzag (ZZ) hairs. We describe a three-dimensional hydrogel culture system that supports clonal growth of CD133+Sox2+, CD133+Sox2−, and CD133−Sox2− (non-DP) neonatal dermal cells. All three cell populations formed spheres that expressed the DP markers alkaline phosphatase, α8 integrin, and CD133. Nevertheless, spheres formed by CD133− cells did not efficiently support hair follicle formation in skin reconstitution assays. In the presence of freshly isolated P2 dermal cells, CD133+Sox2+ and CD133+Sox2− spheres contributed to the DP of both AA and ZZ hairs. Hair type did not correlate with sphere size. Sox2 expression was maintained in culture, but not induced significantly in Sox2− cells in vitro or in vivo, suggesting that Sox2+ cells are a distinct cellular lineage. Although Sox2+ cells were least efficient at forming spheres, they had the greatest ability to contribute to DP and non-DP dermis in reconstituted skin. As the culture system supports clonal growth of DP cells and maintenance of distinct DP cell types, it will be useful for further analysis of intrinsic and extrinsic signals controlling DP function
2022 Canadian Cardiovascular Society Guideline for Use of GLP-1 Receptor Agonists and SGLT2 Inhibitors for Cardiorenal Risk Reduction in Adults
This guideline synthesizes clinical trial data supporting the role of glucagon-like peptide-1 receptor agonists and sodium-glucose co-transporter 2 inhibitors (SGLT2i) for treatment of heart failure (HF), chronic kidney disease, and for optimizing prevention of cardiorenal morbidity and mortality in patients with type 2 diabetes. It is on the basis of a companion systematic review and meta-analysis guided by a focused set of population, intervention, control, and outcomes (PICO) questions that address priority cardiorenal end points. The Grading of Recommendations, Assessment, Development, and Evaluation (GRADE) system and a modified Delphi process were used. We encourage comprehensive assessment of cardiovascular (CV) patients with routine measurement of estimated glomerular filtration rate, urinary albumin-creatinine ratio, glycosylated hemoglobin (A1c), and documentation of left ventricular ejection fraction (LVEF) when evaluating symptoms of HF. For patients with HF, we recommend integration of SGLT2i with other guideline-directed pharmacotherapy for the reduction of hospitalization for HF when LVEF is \u3e 40% and for the reduction of all-cause and CV mortality, hospitalization for HF, and renal protection when LVEF is ≤ 40%. In patients with albuminuric chronic kidney disease, we recommend integration of SGLT2i with other guideline-directed pharmacotherapy to reduce all-cause and CV mortality, nonfatal myocardial infarction, and hospitalization for HF. We provide recommendations and algorithms for the selection of glucagon-like peptide-1 receptor agonists and SGLT2i for patients with type 2 diabetes and either established atherosclerotic CV disease or risk factors for atherosclerotic CV disease to reduce all-cause and CV mortality, nonfatal stroke, and for the prevention of hospitalization for HF and decline in renal function. We offer practical advice for safe use of these diabetes-associated agents with profound cardiorenal benefits
Recommended from our members
1963
Trees for a Beautiful Golf Course by Philip Scott (page 1) The Golf Course\u27s Worst Enemy by Charles Amorim and Hal Haskell (2) Message from the President by James f. Gilligan (2) Turf Management Club News (3) Quotes from 1962 Freshman (4) When I consider How my Night is Spent Leonard Mailloux(5) Protection of a Golf Course by Pay Lucas Jr. (6) Safety - The Superintendents\u27 Responsibility by Gerald Peters (7) Picture - Senior Stockbridge Turf Majors (8) Picture - Freshmen Stockbridge Turf Majors (9) Kansas - In the Transition Zone by Carl Beer (10 Seeds by Don Daigle (11) Picture - Dean F. P. Jeffrey, Dr. W.G. Colby and Director J. R. Beattie (12) Picture - Graduates of Winter School for Turf Managers - 1963 (13) The Effect of Last Year\u27s Weather Upon This Year\u27s Incidence of Turf Insects by John C. Schread (A-1) Labor-Management Relations by Mortimer H. Gavin S.J. (A-4) Massachusetts Labor Laws by Andrew C. SInclair (A-7) Golf Course Budget by John Espey (A-10) Golf Course Budgets by Robert St. Thomas (A-12) Purpose & Method of Budgeting by Leon St. Pierre (A-13) The Committee Chairman, His Duties by Charles Connelly (A-16) Long-range vs. Short-range Planning by George Farber (A-18) The Golf Course Superintendent, His Duties by Sherwood Moore (A-20) The Budget by Leo Kowalski (A-25) Public Relations by Leon St. Pierre (A-26) A Study of WIlt by Harry Meusal (A-28) Specifications for a Method of Putting Green Construction by Alexander Radko (A-33) Management of Kentucky Bluegrass & Grass Mixtures for Turf by F.V. Juska (A-38) What\u27s New in Fertilizers by Geoffrey S. Cornish (A-40) Methylene Ureas by Harvey Stangel (A-42) Plastic Coated Fertilizers by Louis I. Hansen (A-44) The Role of Sewage Sludge by James Latham Jr. (A-49) The Role of Ureaforms in the Turf Fertilizer Industry by Robert T. Miller (A-51) Why Low Phosphorus & Higher Potassium by L. J. Sullivan (A-55) Uptake of Potassium by Evangel Bredakis (A-59) Responsibility of Industry & Community in Land Usage & Plantings by Joseph L. Beasley (A-61) Turf & Other Planting Problems by H. Thurston Handley Jr. (A-65) Weeds & Diseases by Dominic Marini (A-67) General Maintenacne & Equipment by Lewis Hodgkinson (A-68) Fertilizer Problems by William J. Bennett (A-70) Lawn Construction & Insect Problems by herbert C. Fordham (A-71
- …