Method for reducing snap in magnetic amplifiers

Method of reducing snap in magnetic amplifiers uses a degenerative feedback circuit consisting of a resistor and a separate winding on a magnetic core. The feedback circuit extends amplifier range by allowing it to be used at lower values of output current

Evaluation of dredged material proposed for ocean disposal from MOTBY

The National Park Service, US Department of the Interior requested U.S. Army Corps of Engineers/New York District (USACE-NYD) to evaluate sediments around the Military Ocean Terminal (MOTBY) in Bayonne, New Jersey for unconfined ocean disposal at the Mud Dump Site. Sediment samples were collected from MOTBY. Tests and analyses were conducted on MOTBY sediment core samples. The evaluation of proposed dredged material from MOTBY included grain size and total organic carbon (TOC) analyses and one acute toxicity test with the amphipod Ampelisca abdita. In addition to this benthic toxicity test, a bioaccumulation test (28-day exposure) was conducted

How birds cope physiologically and behaviourally with extreme climatic events

As global climate change progresses, the occurrence of potentially disruptiveclimatic events such as storms are increasing in frequency, duration and inten-sity resulting in higher mortality and reduced reproductive success. Whatconstitutes an extreme climatic event? First we point out that extreme climaticevents in biological contexts can occur in any environment. Focusing on fieldand laboratory data on wild birds we propose a mechanistic approach to defin-ing and investigating what extreme climatic events are and how animals copewith them at physiological and behavioural levels. The life cycle of birds ismade up of life-history stages such as migration, breeding and moult thatevolved to match a range of environmental conditions an individual mightexpect during the year. When environmental conditions deteriorate anddeviate from the expected range then the individual must trigger copingmechanisms (emergency life-history stage) that will disrupt the temporal pro-gression of life-history stages, but enhance survival. Using the framework ofallostasis, we argue that an extreme climatic event in biological contexts canbe defined as when the cumulative resources available to an individual areexceeded by the sum of its energetic costs—a state called allostatic overload.This allostatic overload triggers the emergency life-history stage that tempor-arily allows the individual to cease regular activities in an attempt to surviveextreme conditions. We propose that glucocorticoid hormones play a majorrole in orchestrating coping mechanisms and are critical for enduring extremeclimatic events.This article is part of the themed issue ‘Behavioural, ecological andevolutionary responses to extreme climatic events’

X-Ray Resonant Scattering as a Direct Probe of Orbital Ordering in Transition-Metal Oxides

X-ray resonant scattering at the K-edge of transition metal oxides is shown to measure the orbital order parameter, supposed to accompany magnetic ordering in some cases. Virtual transitions to the 3d-orbitals are quadrupolar in general. In cases with no inversion symmetry, such as V$_2$O$_3$, treated in detail here, a dipole component enhances the resonance. Hence, we argue that the detailed structure of orbital order in V$_2$O$_3$ is experimentally accessible.Comment: LaTex using RevTex, 4 pages and two included postscript figure

Theory for Phase Transitions in Insulating Vanadium Oxide

We show that the recently proposed S=2 bond model with orbital degrees of freedom for insulating V$_{2}$O$_{3}$ not only explains the anomalous magnetic ordering, but also other mysteries of the magnetic phase transition. The model contains an additional orbital degree of freedom that exhibits a zero temperature quantum phase transtion in the Ising universality class.Comment: 5 pages, 2 figure

Ground State and Excitations of Spin Chain with Orbital Degeneracy

The one dimensional Heisenberg model in the presence of orbital degeneracy is studied at the SU(4) symmetric viewpoint by means of Bethe ansatz. Following Sutherland's previous work on an equivalent model, we discuss the ground state and the low-lying excitations more extensively in connection to the spin systems with orbital degeneracy. We show explicitly that the ground state is a SU(4) singlet. We study the degeneracies of the elementary excitations and the spectra of the generalized magnons consisting of these excitations. We also discuss the complex 2-strings in the context of the Bethe ansatz solutions.Comment: Revtex, 9 pages, 3 figures; typos correcte

Orbitally Degenerate Spin-1 Model for Insulating V2O3

Motivated by recent neutron, X-ray absorption and resonant scattering experiments, we revisit the electronic structure of V2O3. We propose a model in which S=1 V3+ ions are coupled in the vertical V-V pairs forming two-fold orbitally degenerate configurations with S=2. Ferro-orbital ordering of the V-V pairs gives a description which is consistent with all experiments in the antiferromagnetic insulating phase.Comment: 4 pages, including three figure

Evaluation of Dredged Material Proposed for Ocean Disposal from Port Chester, New York

Port Chester was one of seven waterways that the US Army Corps of Engineers-New York District requested the Battelle Marine Sciences Laboratory to sample and evaluate for dredging and disposal in March 1994. Tests and analyses were conducted on Port Chester sediment core samples. Because the Port Chester area is located on the border between New York and southeast Connecticut, its dredged material may also be considered for disposal at the Central Long Island Sound Disposal Site. The sediment evaluation consisted of bulk sediment chemical analyses, chemical analyses of site water and dredged material elutriate preparations, water-column and benthic acute toxicity tests, and bioaccumulation studies. Individual sediment core samples collected from Port Chester were analyzed for grain size, moisture content, and total organic carbon. In addition, sediment was analyzed for bulk density, specific gravity, metals, chlorinated pesticides, polychlorinated biphenyl congers, polynuclear aromatic hydrocarbons and 1,4-dichlorobenzene

Evaluation of dredged material proposed for ocean disposal from Buttermilk Channel, New York

Buttermilk Channel was one of seven waterways that was sampled and evaluated for dredging and sediment disposal. Sediment samples were collected and analyses were conducted on sediment core samples. The evaluation of proposed dredged material from the channel included bulk sediment chemical analyses, chemical analyses of site water and elutriate, water column and benthic acute toxicity tests, and bioaccumulation studies. Individual sediment core samples were analyzed for grain size, moisture content, and total organic carbon. A composite sediment samples, representing the entire area proposed for dredging, was analyzed for bulk density, polynuclear aromatic hydrocarbons, and 1,4-dichlorobenzene. Site water and elutriate were analyzed for metals, pesticides, and PCBs