LATE-SUMMER FEEDING PATTERNS OF RED-WINGED BLACKBIRDS IN A SUNFLOWER-GROWING AREA OF NORTH DAKOTA

During August and September in 1977 and 1978, we monitored the feeding patterns of radio-equipped, male red-winged blackbirds (Agelaius phoeniceus) and associated blackbird flocks in the vicinity of Fuller’s Lake Waterfowl Production Area in Steele County in east-central North Dakota. Fuller’s Lake, a cattail marsh of about 1,000 acres (405 ha), serves as the main roosting area for a blackbird assemblage that, for the past seven years in late summer, has numbered from 100,000 in wet years to more than 750,000 in dry years. Sunflower is an important crop in the Fuller’s Lake area, being grown on about 20 percent of cropland. Wheat and barley are other major crops, grown on about 40 percent of the cropland. Corn is grown on less than 1 percent of the cropland, but the number of quarter-section (160-acre, 65 ha), irrigated cornfields increased in the area from two in 1977 to eight in 1978. The Fuller’s Lake area lies on the eastern edge of the North Dakota Drift Plains and is poorly drained, with as many as a dozen water basins per square mile. This combination of a large roosting marsh and numerous satellite roosting and loafing marshes, intermingled with sunflower fields, has created optimum conditions for blackbirds to damage some sunflower fields. Damage was estimated at 23.6 percent of the sunflower crop in a 28-section area surrounding Fuller’s Lake in 1972 (Besser and Guarino 1977), when little control effort was expended. Experiments were conducted with 4-aminopyridine baits as a frightening agent to protect sunflowers from blackbird damage in a 7-township (3-county) study area in the Fuller’s Lake area in 1977 and 1978. In 1977, 31 of the most heavily damaged fields were baited with Avitrol® FC-Corn Chops 99S (Henne 1978), but in 1978 only five were baited (Henne et al. 1979). These experiments afforded us an excellent opportunity to monitor the feeding patterns of blackbirds frightened from ripening sunflower fields as well as undisturbed birds. In some instances, when a feeding pattern had been established by a flock in an untreated ripening sunflower field, we frightened the flock from the field by mechanical means. This paper presents the major findings of this 2-year study

Applications and limitations of electron correlation microscopy to study relaxation dynamics in supercooled liquids

Electron correlation microscopy (ECM) is a way to measure structural relaxation times, τ, of liquids with nanometer-scale spatial resolution using coherent electron scattering equivalent of photon correlation spectroscopy. We have applied ECM with a 3.5 nm diameter probe to Pt57.5Cu14.7Ni5.3P22.5 amorphous nanorods and Pd40Ni40P20 bulk metallic glass (BMG) heated inside the STEM into the supercooled liquid region. These data demonstrate that the ECM technique is limited by the characteristics of the time series, which must be at least 40τ to obtain a well-converged correlation function g2(t), and the time per frame, which must be less than 0.1τ to obtain sufficient sampling. A high-speed direct electron camera enables fast acquisition and affords reliable g2(t) data even with low signal per frame

A macroinvertebrate assessment of Ozark streams located in lead–zinc mining areas of the Viburnum Trend in southeastern Missouri, USA

The Viburnum Trend lead–zinc mining subdistrict is located in the southeast Missouri portion of the Ozark Plateau. In 2003 and 2004, we assessed the ecological effects of mining in several watersheds in the region. We included macroinvertebrate surveys, habitat assessments, and analysis of metals in sediment, pore water, and aquatic biota. Macroinvertebrates were sampled at 21 sites to determine aquatic life impairment status (full, partial, or nonsupport) and relative biotic condition scores. Macroinvertebrate biotic condition scores were significantly correlated with cadmium, nickel, lead, zinc, and specific conductance in 2003 (r = −0.61 to −0.68) and with cadmium, lead, and pore water toxic units in 2004 (r = −0.55 to −0.57). Reference sites were fully supporting of aquatic life and had the lowest metals concentrations and among the highest biotic condition scores in both years. Sites directly downstream from mining and related activities were partially supporting, with biotic condition scores 10% to 58% lower than reference sites. Sites located greater distances downstream from mining activities had intermediate scores and concentrations of metals. Results indicate that elevated concentrations of metals originating from mining activities were the underlying cause of aquatic life impairment in several of the streams studied. There was a general concurrence among the adversely affected sites in how the various indicators responded to the mining activities during the overall study

Coupling biochemistry and mechanics in cell adhesion: a model for inhomogeneous stress fiber contraction

Biochemistry and mechanics are closely coupled in cell adhesion. At sites of cell-matrix adhesion, mechanical force triggers signaling through the Rho-pathway, which leads to structural reinforcement and increased contractility in the actin cytoskeleton. The resulting force acts back to the sites of adhesion, resulting in a positive feedback loop for mature adhesion. Here we model this biochemical-mechanical feedback loop for the special case when the actin cytoskeleton is organized in stress fibers, which are contractile bundles of actin filaments. Activation of myosin II molecular motors through the Rho-pathway is described by a system of reaction-diffusion equations, which are coupled into a viscoelastic model for a contractile actin bundle. We find strong spatial gradients in the activation of contractility and in the corresponding deformation pattern of the stress fiber, in good agreement with experimental findings.Comment: Revtex, 35 pages, 13 Postscript figures included, in press with New Journal of Physics, Special Issue on The Physics of the Cytoskeleto

Development of metal-clad filled evacuated panel superinsulation

This Cooperative Research and Development Agreement (CRADA) was between Aladdin Industries, Inc. and Lockheed Martin Energy Research Corp. The purpose of the CRADA was to determine the thermal performance of various metal claddings used to encapsulate Filled Evacuated Panel (FEP) superinsulation and to optimize the cost versus thermal performance of the claddings. A FEP superinsulation is a new type of superinsulation with the potential for saving large amounts of energy in buildings, building equipment, transportation (refrigerated railcars and trucks), industrial applications, etc. The major disadvantage of metal claddings for FEPs is the heat loss through the cladding caused by the high thermal conductivity of most metals. In smaller FEPs, this heat loss can degrade the overall performance of the FEP by factors of two or more as compared with polymer-clad FEPs. On the other hand, metal claddings are essentially impermeable to ambient air, whereas polymer claddings are not. Thus, the longevity and reliability of metal-clad FEPs are much superior to polymer-clad FEPs. In addition, because of the very low vapor pressure of metals as compared to polymers, metal-clad FEPs can achieve and operate at lower internal pressures. These lower pressures allow use of less expensive and/or higher performance filler materials

Phase transitions for PP-adic Potts model on the Cayley tree of order three

In the present paper, we study a phase transition problem for the $q$-state $p$-adic Potts model over the Cayley tree of order three. We consider a more general notion of $p$-adic Gibbs measure which depends on parameter \rho\in\bq_p. Such a measure is called {\it generalized $p$-adic quasi Gibbs measure}. When $\rho$ equals to $p$-adic exponent, then it coincides with the $p$-adic Gibbs measure. When $\rho=p$, then it coincides with $p$-adic quasi Gibbs measure. Therefore, we investigate two regimes with respect to the value of $|\rho|_p$. Namely, in the first regime, one takes $\rho=\exp_p(J)$ for some J\in\bq_p, in the second one $|\rho|_p<1$. In each regime, we first find conditions for the existence of generalized $p$-adic quasi Gibbs measures. Furthermore, in the first regime, we establish the existence of the phase transition under some conditions. In the second regime, when $|\r|_p,|q|_p\leq p^{-2}$ we prove the existence of a quasi phase transition. It turns out that if $|\r|_p<|q-1|_p^2<1$ and \sqrt{-3}\in\bq_p, then one finds the existence of the strong phase transition.Comment: 27 page

Structural hierarchy as a key to complex phase selection in Al-Sm

Investigating the unknown structure of the complex cubic phase, previously observed to crystallize from melt-spun amorphous Al–10 at.% Sm alloy, we determine the structure in full site-occupancy detail, highlighting several critical structural features that govern the far-from-equilibrium phase selection pathway. Using an efficient genetic algorithm combining molecular dynamics, density functional theory, and x-ray diffraction, the structure is clearly identified as body-centered cubic Im¯3m (No. 229) with ∼140 atoms per cubic unit cell and a lattice parameter of 1.4 nm. The complex structure is further refined to elucidate the detailed site occupancy, revealing full Sm occupancy on 6b sites and split Sm/Al occupancy on 16f sites. Based on the refined site occupancy associated with the experimentally observed phase, we term this phase ɛ−Al60Sm11(bcc), corresponding to the limiting situation when all 16f sites are occupied by Sm. However, it should be recognized that the range of solubility enabled by split occupancy at Sm sites is an important feature in phase selection under experimental conditions, permitting an avenue for transition with little or no chemical partitioning. Our analysis shows that the ɛ−Al60Sm11(bcc) exhibits a “3-6-6-1” first-shell packing around Sm centers on 16f sites, the same dominant motif exhibited by the undercooled liquid. The coincident motif supports the notion that liquid/glass ordering at high undercooling may give rise to topological invariants between the noncrystalline and crystalline states that provide kinetic pathways to metastable phases that are not accessible during near-equilibrium processing

Electrically controlled long-distance spin transport through an antiferromagnetic insulator

Spintronics uses spins, the intrinsic angular momentum of electrons, as an alternative for the electron charge. Its long-term goal is in the development of beyond-Moore low dissipation technology devices. Recent progress demonstrated the long-distance transport of spin signals across ferromagnetic insulators. Antiferromagnetically ordered materials are however the most common class of magnetic materials with several crucial advantages over ferromagnetic systems. In contrast to the latter, antiferromagnets exhibit no net magnetic moment, which renders them stable and impervious to external fields. In addition, they can be operated at THz frequencies. While fundamentally their properties bode well for spin transport, previous indirect observations indicate that spin transmission through antiferromagnets is limited to short distances of a few nanometers. Here we demonstrate the long-distance, over tens of micrometers, propagation of spin currents through hematite (\alpha-Fe2O3), the most common antiferromagnetic iron oxide, exploiting the spin Hall effect for spin injection. We control the spin current flow by the interfacial spin-bias and by tuning the antiferromagnetic resonance frequency with an external magnetic field. This simple antiferromagnetic insulator is shown to convey spin information parallel to the compensated moment (N\'eel order) over distances exceeding tens of micrometers. This newly-discovered mechanism transports spin as efficiently as the net magnetic moments in the best-suited complex ferromagnets. Our results pave the way to ultra-fast, low-power antiferromagnet-insulator-based spin-logic devices that operate at room temperature and in the absence of magnetic fields