Our aim was to describe shifts in autumn and winter harvest distributions of three species of dabbling ducks (blue‐winged teal Spatula discors, mallard Anas platyrhynchos, and northern pintail Anas ...acuta) in the Central and Mississippi flyways of North America during 1960–2019. We measured shifts in band recovery distributions corrected for changes in hunting season dates and zones by using kernel density estimators to calculate 10 distributional metrics. We then assessed interannual and intraspecific variation by comparing species‐specific changes in distributional metrics for 4 months (October–January) and three geographically based subpopulations. During 1960–2019, band recovery distributions shifted west‐ and southwards (blue‐winged teal) or east‐ and northwards (mallard and northern pintail) by one hundred to several hundred kilometers. For all three species, the broad (95% isopleth) and core distributions (50% isopleth) showed widespread decreases in overlap and increases in relative area compared to a 1960–1979 baseline period. Shifts in band recovery distributions varied by month, with southward shifts for blue‐winged teal most pronounced in October and northward shifts for mallard and northern pintail greatest during December and January. Finally, distributional metric response varied considerably among mallard subpopulations, including 2–4‐fold differences in longitude, latitude, and overlap, whereas differences among subpopulations were minimal for blue‐winged teal and northern pintail. Our findings support the popular notion that winter (December–January) distributions of duck species have shifted north; however, the extent and direction of distributional changes vary among species and subpopulations. Long‐term distributional changes are therefore complex and summarizing shifts across species, months, or subpopulations could mask underlying finer‐scale patterns that are important to habitat conservation and population management. A detailed understanding of how species distributions have changed over time will help quantify important drivers of species occurrence, identify habitat management options, and could inform decisions on where to focus conservation or restoration efforts.
Maps of 95% isopleths of utilization distributions of blue‐winged teal, mallard, and northern pintail bands recovered in the Central and Mississippi flyways of North America between 1960 and 2019 for the banding region and month in which species‐specific shifts were greatest. Shown are isopleths (polygons) and centroid locations (points) of bands recovered during 1960–1969 (gray/black) or 2010–2019 (red).
Geographical distributions of waterfowl exhibit annual variation in response to spatiotemporal variation in weather conditions, habitat availability, and other factors. Continuing changes in climate ...and land use could lead to persistent shifts of waterfowl distributions, potentially causing a mismatch with habitat conservation planning, wetland restoration efforts, and harvest management decisions informed by historical distributions. We used band recoveries and harvest records (i.e., hunter‐harvested wings) from the United States Fish and Wildlife Service Waterfowl Parts Collection Survey as indices of duck distribution in autumn and winter, and quantified intra‐annual, interannual, and interspecific variation in their geographic distributions across 6 decades (1960–2019) for 15 duck species in the Central and Mississippi flyways in North America. Specifically, we tested for annual and decadal shifts in mean latitude and longitude of recoveries for each month (Oct–Jan) by species and taxonomic guild (i.e., dabbling, diving ducks). Overall, species varied in the extent, timing, and sometimes direction, of distributional change in recoveries. From 1960–2019, mean recovery locations for dabbling ducks shifted south 105–296 km in October and 27 km in November (wings only), whereas mean latitudes shifted north 144–234 km in December and 186–301 km in January. Mean recovery locations for diving ducks shifted north 162 km in October (wings only), 84–173 km in December, and 66–120 km in January, but shifted 99–512 km south in November. Shifts in longitude were less consistent between guilds and data types. Finally, distributional change rarely accelerated during recent decades, except for southward shifts of band recoveries of diving ducks in November and northward shifts of band and wing recoveries of dabbling ducks in January. Although anecdotal accounts of large‐scale northward shifts in duck distributions are prolific in the land management and hunting communities, our data demonstrate more subtle shifts that vary considerably by species and month. Observed changes in recovery distributions could necessitate changes in timing of habitat management practices throughout the Central and Mississippi flyways and may result in fewer hunting and recreational opportunities for some species in southern states. Quantifying patterns of historical change is a necessary first step to understanding temporal and interspecific variation in waterfowl distributions, which will help with landscape‐scale conservation and management efforts in the future and enable effective communication to core constituencies regarding ongoing changes and their implications for recreational engagement.
We used band recoveries and hunter‐harvested wings as indices of duck distributions in autumn and winter, and estimated intra‐annual, interannual, and interspecific variation in geographic distributions across 6 decades (1960–2019) for 15 duck species in the Central and Mississippi Flyways in North America. Mean latitude of band and wing recovery distributions has shifted south in October and November, and north in December and January by several hundred kilometers for most species, and there was considerable variation in distributional shifts among species and taxonomic guilds (dabbling vs. diving ducks).
This paper describes an approach to harvesting electrical energy from a mechanically excited piezoelectric element. A vibrating piezoelectric device differs from a typical electrical power source in ...that it has a capacitive rather than inductive source impedance, and may be driven by mechanical vibrations of varying amplitude. An analytical expression for the optimal power flow from a rectified piezoelectric device is derived, and an "energy harvesting" circuit is proposed which can achieve this optimal power flow. The harvesting circuit consists of an AC-DC rectifier with an output capacitor, an electrochemical battery, and a switch-mode DC-DC converter that controls the energy flow into the battery. An adaptive control technique for the DC-DC converter is used to continuously implement the optimal power transfer theory and maximize the power stored by the battery. Experimental results reveal that use of the adaptive DC-DC converter increases power transfer by over 400% as compared to when the DC-DC converter is not used.
An optimized method of harvesting vibrational energy with a piezoelectric element using a step-down DC-DC converter is presented. In this configuration, the converter regulates the power flow from ...the piezoelectric element to the desired electronic load. Analysis of the converter in discontinuous current conduction mode results in an expression for the duty cycle-power relationship. Using parameters of the mechanical system, the piezoelectric element, and the converter; the "optimal" duty cycle can be determined where the harvested power is maximized for the level of mechanical excitation. It is shown that, as the magnitude of the mechanical excitation increases, the optimal duty cycle becomes essentially constant, greatly simplifying the control of the step-down converter. The expression is validated with experimental data showing that the optimal duty cycle can be accurately determined and maximum energy harvesting attained. A circuit is proposed which implements this relationship, and experimental results show that the converter increases the harvested power by approximately 325%.
Primary immunodeficiency (PID) is a rare group of disorders that manifest similarly with infection, neoplasms, allergic, and autoimmune diseases, and are treated with injectable medications. Often ...the burden of disease and cost of management is excessive, and premature death is not uncommon. In light of these features of PID, it was our objective to survey our cohort to assess for factors that can influence depression and anxiety.
We used an investigator-developed survey, in addition to the Hamilton Depression Rating Scale (HAM-D) and the Hamilton Anxiety Rating Scale, after institutional review board approval of our pilot study, to determine the extent of anxiety and depression that our patients with PID experienced and variables that may have affected the difference of expression. The differences among groups were tested by using Wilcoxon rank sum tests, Kruskal-Wallis tests, and chi-square tests.
The patients with PID had similar depression compared with the U.S. population, as assessed by the HAM-D scale. Risk factors associated with elevated HAM-D scores included the following: not driving, intravenous immunoglobulin therapy (versus subcutaneous), nurse-administered therapy (versus self-administered), having unpleasant adverse effects from therapy, previously attempted suicide, and family members with reported anxiety and/or depression. Anxiety was not significantly increased in our cohort. Risk factors for significantly elevated Hamilton Anxiety Rating Scale scores included the following: having poor health, an unhealthy diet, lack of refreshing sleep, and family members with reported anxiety and/or depression.
Many factors influence depression and anxiety, and may add to the morbidity of PID. Patients should be assessed for our identified factors for depression and anxiety. Treatment or referrals should be initiated as it is hoped to improve our patients' quality of life and outcomes.
The recent development of electrostrictive polymers has generated new opportunities for high-strain actuators. At the current time, the investigation of using electrostrictive polymer for energy ...harvesting, or mechanical to electrical energy conversion, is beginning to show its potential for this application. In this paper we discuss the mechanical and electrical boundary conditions for maximizing the energy harvesting density and mechanical-to-electrical coupling of electrostrictive materials. Mathematical models for different energy harvesting approaches were developed under quasistatic assumptions. Energy harvesting densities then are determined for representative electrostrictive material properties using these models. Comparison with a magnetic-based energy harvesting system suggests that electrostrictive energy harvesting systems are preferable for "small" energy harvesting applications with low-frequency excitation.
One key parameter in using electroactive materials to harvest electric energy from mechanical sources is the energy conversion efficiency. Recently, it was shown that, in the relaxor ferroelectric ...PMN-PT single crystals, a very high longitudinal electromechanical coupling factor (>90%) can be obtained. This paper investigates energy harvesting using 1-3 composites of PMN-PT single crystals in a soft epoxy matrix. It is shown that 1-3 composites enable the single crystals operating in the longitudinal mode to achieve high efficiency for energy harvesting, and the soft-polymer, matrix-supported single-crystal rods maintain high mechanical integrity under different external loads. For comparison, 1-3 composites with piezoceramic PZT also are investigated in energy-harvesting applications, and the results show that the high coupling factor of single crystal PMN-PT 1-3 composites leads to much higher electric energy output for similar mechanical energy input. The harvested energy density of 1-3 composite with single crystal (22.1 mW/cm/sup 3/ under a stress of 40.4 MPa) is about twice of that harvested with PZT ceramic 1-3 composite (12 mW/cm/sup 3/ under a stress of 39 MPa). At a higher stress level, the harvested-energy density of 1-3 PMN-PT single crystal composite can reach 96 mW/cm/sup 3/.
This paper presents a position-sensorless vector torque controller designed to achieve maximum efficiency over a range of power and rotational speed for a synchronous reluctance machine. A model of ...the synchronous reluctance machine is presented which incorporates both winding and core losses. It is then shown that a stator-flux-oriented control scheme can achieve synchronous operation of the machine without a position sensor at medium and high electrical frequencies. For a given speed and torque, power losses in the machine are shown to be a function of only the stator flux magnitude. As the power losses are a convex function of the stator flux level, the optimal flux value can be found using a one-dimensional optimization algorithm, such as the Method of Sequential Quadratic Interpolations. Optimal flux values for a synchronous reluctance machine are determined using an experimental setup that accurately determines losses in the motor/drive system. Experimental results obtained from the test setup confirm the validity of the controller and the optimization algorithm.
Bordetella pertussis is a human pathogen that can infect the respiratory tract and cause the disease known as whooping cough. B. pertussis uses pertussis toxin (PT) and adenylate cyclase toxin (ACT) ...to kill and modulate host cells to allow the pathogen to survive and persist. B. pertussis encodes many uncharacterized transcription factors, and very little is known about their functions. RpoE is a sigma factor which, in other bacteria, responds to oxidative, heat, and other environmental stresses. RseA is a negative regulator of RpoE that sequesters the sigma factor to regulate gene expression based on conditions. In B. pertussis, deletion of the rseA gene results in high transcriptional activity of RpoE and large amounts of secretion of ACT. By comparing parental B. pertussis to an rseA gene deletion mutant (PM18), we sought to characterize the roles of RpoE in virulence and determine the regulon of genes controlled by RpoE. Despite high expression of ACT, the rseA mutant strain did not infect the murine airway as efficiently as the parental strain and PM18 was killed more readily when inside phagocytes. RNA sequencing analysis was performed and 263 genes were differentially regulated by RpoE, and surprisingly, the rseA mutant strain where RpoE activity was elevated expressed very little pertussis toxin. Western blots and proteomic analysis corroborated the inverse relationship of PT to ACT expression in the high-RpoE-activity rseA deletion strain. Our data suggest that RpoE can modulate PT and ACT expression indirectly through unidentified mechanisms in response to conditions.
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