1,635 research outputs found
REGIONAL ECONOMIC IMPACTS OF A WATERSHED PLANNING PROCESS TO REDUCE EROSION AND STREAM SEDIMENTATION
Farm-level and watershed-wide land-use changes resulting from policy initiatives are linked to a regional input/output model. As a result not only can the direct economic impacts at the farm and watershed levels be determined, so too can the direct and induced economic impacts at the regional level.Resource /Energy Economics and Policy,
Framing Contemporary U.S. Wild Horse and Burro Management Processes in a Dynamic Ecological, Sociological, and Political Environment
The Wild Free-Roaming Horses and Burros Act (WFRHBA) of 1971 established all “unbranded or unclaimed” equids on U.S. public lands as “living symbols of the historic and pioneer spirit of the West.” Today, \u3e72,000 feral horses (Equus ferus caballus) and burros (E . asinus ; WHB) live on western U.S. public rangelands. The number of WHBs exceeds the Bureau of Land Management’s maximum Appropriate Management Level (AML) of 26,715 by a factor of approximately 2.7 and has nearly doubled from 2007–2015. The AML was set to balance WHB numbers with rangeland health and support other uses such as wildlife habitat and livestock grazing. Thus, public land management agencies must manage WHB under the multiple-use context. This becomes more problematic when WHB populations go largely unmanaged and excessive equid grazing negatively impacts rangeland vegetation, native wildlife, and livestock forage. In addition, approximately 46,000 WHBs exist in off -range holding facilities, further straining federal budgets. Contemporary management actions are being constrained by: (1) litigation that has stymied federal government WFRHBA enforcement eff orts, (2) public emotional concerns that lack reconciliation with the current situation, and (3) increasing complexity in the laws and subsequent amendments shaping WHB management policy. Collectively, these factors impede the implementation of concrete solutions to restore AML. Consequently, stakeholders are increasing polarized over how WHBs are or should be managed. While the ecological and animal health and welfare implications of unmanaged WHB populations are somewhat understood, publicly acceptable strategies to maintain healthy populations, healthy and functioning rangelands, and multiple uses that sustain wildlife and local communities remain unresolved
Spatial Ecology Observations From Feral Horses Equipped With Global Positioning System Transmitters
Our understanding of the spatial ecology of feral horses (Equus ferus caballus ) and burros (E . asinus ) in the United States is limited. Robust location data are needed to better understand the permeability of Bureau of Land Management Herd Management Area boundaries, relative to feral horse movement patterns and home ranges. To increase our understanding of feral horse movement, in February to March 2017, we deployed global positioning system (GPS) collars on 14 females ≥5 years old that were captured in the Adobe Town Herd Management Area (ATHMA) of southcentral Wyoming, USA. Herein, we report initial results from movement data collected during summer (May 15 to September 15) 2017 for 9 horses. We limited our focus to these 9 horses because we received at least 2 months of continuous GPS location data from them during summer 2017. Feral horse daily movement distances averaged 9.0 km (SE = 0.3), and mean summer total home range size was 40.4 km2 (SE = 6.7). Of GPS location fixes obtained, 44.9% were outside ATHMA and 10.8% were on private land. Our results highlight the types of data that GPS collars can provide and illustrate the difficulties of managing free-roaming species such as horses and burros on landscapes with heterogeneous sociopolitical patterns. Expanded use of such technology on feral horses and burros in the United States will yield greater insight on spatial complexities constraining management
Potential and Pitfalls of Prescribed Burning Big Sagebrush Habitat to Enhance Nesting and Early Brood-Rearing Habitats for Greater Sage-Grouse
We describe short-term (≤10 yrs) and long-term (\u3e10 yrs) responses of prescribed burning to enhance nesting and early brood-rearing habitat for greater sage-grouse (Centrocercus urophasianus). Our primary objective was to provide a literature synthesis to identify short- and long-term responses of prescribed burning to important components of sage-grouse nesting and early brood-rearing habitats in mountain (Artemisia tridentata vaseyana) and Wyoming (A. t. wyomingensis) big sagebrush. In our synthesis, we evaluated ecological status (bare ground and litter), food availability (forbs and insects), and vegetation structure (grass and sagebrush cover). We used six criteria to identify n = 12 papers providing meaningful and rigorous results. Of these papers, six reported the effects of burning in mountain big sagebrush; seven in Wyoming big sagebrush; and one provided information for mountain and Wyoming big sagebrush. Our findings point to some potential for short-term enhancement of forbs and grasses in mountain big sagebrush, but no long-term enhancement of herbs in mountain big sagebrush or short- or long-term enhancement of herbs in Wyoming big sagebrush. In particular, prescribed burning leads to a pronounced negative response in sagebrush cover that lasts for at least a few decades. Based on our findings, we cannot recommend burning Wyoming big sagebrush to enhance sage-grouse nesting or early brood-rearing habitat and we suggest prescribed burning has limited short-term value in enhancing forbs and grasses for sage-grouse inhabiting Mountain big sagebrush
Minimum Renyi and Wehrl entropies at the output of bosonic channels
The minimum Renyi and Wehrl output entropies are found for bosonic channels
in which the signal photons are either randomly displaced by a Gaussian
distribution (classical-noise channel), or in which they are coupled to a
thermal environment through lossy propagation (thermal-noise channel). It is
shown that the Renyi output entropies of integer orders z>1 and the output
Wehrl entropy are minimized when the channel input is a coherent state.Comment: Minimal revision. Accepted for publication on Phys. Rev.
Saving the sagebrush sea: An ecosystem conservation plan for big sagebrush plant communities
Vegetation change and anthropogenic development are altering ecosystems and decreasing biodiversity. Successful management of ecosystems threatened by multiple stressors requires development of ecosystem conservation plans rather than single species plans. We selected the big sagebrush (Artemisia tridentata Nutt.) ecosystem to demonstrate this approach. The area occupied by the sagebrush ecosystem is declining and becoming increasingly fragmented at an alarming rate because of conifer encroachment, exotic annual grass invasion, and anthropogenic development. This is causing rangewide declines and localized extirpations of sagebrush associated fauna and flora. To develop an ecosystem conservation plan, a synthesis of existing knowledge is needed to prioritize and direct management and research. Based on the synthesis, we concluded that efforts to restore higher elevation conifer-encroached, sagebrush communities were frequently successful, while restoration of exotic annual grass-invaded, lower elevation, sagebrush communities often failed. Overcoming exotic annual grass invasion is challenging and needs additional research to improve the probability of restoration and identify areas where success would be more probable. Management of fire regimes will be paramount to conserving sagebrush communities, as infrequent fires facilitate conifer encroachment and too frequent fires promote exotic annual grasses. Anthropogenic development needs to be mitigated and reduced to protect sagebrush communities and this probably includes more conservation easements and other incentives to landowners to not develop their properties. Threats to the sustainability of sagebrush ecosystem are daunting, but a coordinated ecosystem conservation plan that focuses on applying successful practices and research to overcome limitations to conservation is most likely to yield success
Phosphorylation and calcium antagonistically tune myosin-binding protein C\u27s structure and function
During each heartbeat, cardiac contractility results from calcium-activated sliding of actin thin filaments toward the centers of myosin thick filaments to shorten cellular length. Cardiac myosin-binding protein C (cMyBP-C) is a component of the thick filament that appears to tune these mechanochemical interactions by its N-terminal domains transiently interacting with actin and/or the myosin S2 domain, sensitizing thin filaments to calcium and governing maximal sliding velocity. Both functional mechanisms are potentially further tunable by phosphorylation of an intrinsically disordered, extensible region of cMyBP-C\u27s N terminus, the M-domain. Using atomic force spectroscopy, electron microscopy, and mutant protein expression, we demonstrate that phosphorylation reduced the M-domain\u27s extensibility and shifted the conformation of the N-terminal domain from an extended structure to a compact configuration. In combination with motility assay data, these structural effects of M-domain phosphorylation suggest a mechanism for diminishing the functional potency of individual cMyBP-C molecules. Interestingly, we found that calcium levels necessary to maximally activate the thin filament mitigated the structural effects of phosphorylation by increasing M-domain extensibility and shifting the phosphorylated N-terminal fragments back to the extended state, as if unphosphorylated. Functionally, the addition of calcium to the motility assays ablated the impact of phosphorylation on maximal sliding velocities, fully restoring cMyBP-C\u27s inhibitory capacity. We conclude that M-domain phosphorylation may have its greatest effect on tuning cMyBP-C\u27s calcium-sensitization of thin filaments at the low calcium levels between contractions. Importantly, calcium levels at the peak of contraction would allow cMyBP-C to remain a potent contractile modulator, regardless of cMyBP-C\u27s phosphorylation state
Myosin-binding protein C corrects an intrinsic inhomogeneity in cardiac excitation-contraction coupling
The beating heart exhibits remarkable contractile fidelity over a lifetime, which reflects the tight coupling of electrical, chemical, and mechanical elements within the sarcomere, the elementary contractile unit. On a beat-to-beat basis, calcium is released from the ends of the sarcomere and must diffuse toward the sarcomere center to fully activate the myosin- and actin-based contractile proteins. The resultant spatial and temporal gradient in free calcium across the sarcomere should lead to nonuniform and inefficient activation of contraction. We show that myosin-binding protein C (MyBP-C), through its positioning on the myosin thick filaments, corrects this nonuniformity in calcium activation by exquisitely sensitizing the contractile apparatus to calcium in a manner that precisely counterbalances the calcium gradient. Thus, the presence and correct localization of MyBP-C within the sarcomere is critically important for normal cardiac function, and any disturbance of MyBP-C localization or function will contribute to the consequent cardiac pathologies
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Electrophysiological Guidance of Epidural Electrode Array Implantation over the Human Lumbosacral Spinal Cord to Enable Motor Function after Chronic Paralysis.
Epidural electrical stimulation (EES) of the spinal cord has been shown to restore function after spinal cord injury (SCI). Characterization of EES-evoked motor responses has provided a basic understanding of spinal sensorimotor network activity related to EES-enabled motor activity of the lower extremities. However, the use of EES-evoked motor responses to guide EES system implantation over the spinal cord and their relation to post-operative EES-enabled function in humans with chronic paralysis attributed to SCI has yet to be described. Herein, we describe the surgical and intraoperative electrophysiological approach used, followed by initial EES-enabled results observed in 2 human subjects with motor complete paralysis who were enrolled in a clinical trial investigating the use of EES to enable motor functions after SCI. The 16-contact electrode array was initially positioned under fluoroscopic guidance. Then, EES-evoked motor responses were recorded from select leg muscles and displayed in real time to determine electrode array proximity to spinal cord regions associated with motor activity of the lower extremities. Acceptable array positioning was determined based on achievement of selective proximal or distal leg muscle activity, as well as bilateral muscle activation. Motor response latencies were not significantly different between intraoperative recordings and post-operative recordings, indicating that array positioning remained stable. Additionally, EES enabled intentional control of step-like activity in both subjects within the first 5 days of testing. These results suggest that the use of EES-evoked motor responses may guide intraoperative positioning of epidural electrodes to target spinal cord circuitry to enable motor functions after SCI
Reliability of MRI interpretation of Discoid Lateral Meniscus: A multicenter study
BACKGROUND: Discoid lateral meniscus (DLM) has a varied and complex morphology that can be challenging to assess and treat. Preoperative magnetic resonance imaging (MRI) is frequently used for diagnosis and surgical planning; however, it is not known whether surgeons are reliable and accurate in their interpretation of MRI findings when defining the pathomorphology of DLM.
HYPOTHESIS: Surgeons experienced in treating DLM are able to reliably interpret DLM pathology using MRI.
STUDY DESIGN: Cohort study (diagnosis); Level of evidence, 3.
METHODS: Knee MRI scans from 44 patients (45 knees) were selected from a pool of surgically treated patients with DLM. Five reviewers (fellowship-trained pediatric sports medicine surgeons) performed independent review of each MRI scan using the PRiSM Discoid Meniscus Classification. Inter- and intraobserver reliability of the rating factors-primary (width, height, presence of peripheral instability or tear) and secondary (location of instability or tear, tear type)-was assessed using the Fleiss Îş coefficient, designed for multiple readers with nominal variables (fair reliability, 0.21-0.40; moderate, 0.41-0.60; substantial, 0.61-0.80; excellent, 0.81-1.00). Reliability is reported as Îş (95% CI).
RESULTS: Interobserver reliability in assessing most primary and secondary characteristics ranged from substantial (meniscal width) to moderate (peripheral instability, anterior instability, posterior instability, and posterior tear). Intraobserver reliability for most characteristics ranged from substantial (peripheral instability, presence of tear, anterior instability, posterior instability, and posterior tear) to moderate (meniscal width, anterior tear, and tear type). Notable exceptions were presence of tear, anterior tear, and tear type-all with fair interobserver reliability. Height had poor interobserver reliability and fair intraobserver reliability.
CONCLUSION: Orthopaedic surgeons reliably interpret MRI scans using the PRiSM Discoid Meniscus Classification for the majority of DLM characteristics but vary in their assessment of height and presence and type of tear. MRI evaluation may be helpful to diagnose discoid by width and identify the presence of instability: 2 major factors in the decision to proceed with surgery. Arthroscopic evaluation should be used in conjunction with MRI findings for complete DLM diagnosis
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