Isotopic and Micro-Raman investigation of Interplanetary Dust Particles Collected during 2003 Earth passage through Comet Grigg-Skjellerup Dust Stream

We report microscale H and N isotopic and Raman spectral data for IDPs collected in April 2003. The samples show extreme D and 15N enrichments carried by very primitive organic matter. A high abundance of D anomalies might indicate a cometary origin

Diffeomorphism Invariant Integrable Field Theories and Hypersurface Motions in Riemannian Manifolds

We discuss hypersurface motions in Riemannian manifolds whose normal velocity is a function of the induced hypersurface volume element and derive a second order partial differential equation for the corresponding time function $\tau(x)$ at which the hypersurface passes the point $x$. Equivalently, these motions may be described in a Hamiltonian formulation as the singlet sector of certain diffeomorphism invariant field theories. At least in some (infinite class of) cases, which could be viewed as a large-volume limit of Euclidean $M$-branesmoving in an arbitrary $M+1$-dimensional Riemannian manifold, the models are integrable: In the time-function formulation the equation becomes linear (with $\tau(x)$ a harmonic function on the embedding Riemannian manifold). We explicitly compute solutions to the large volume limit of Euclidean membrane dynamics in \Real^3 by methods used in electrostatics and point out an additional gradient flow structure in \Real^n. In the Hamiltonian formulation we discover infinitely many hierarchies of integrable, multidimensional, $N$-component theories possessing infinitely many diffeomorphism invariant, Poisson commuting, conserved charges.Comment: 15 pages, LATE

A Survey of Information Sources Used for Progress Decisions about Medical Students

Although many medical schools have adopted a variety of methods to assess student competency, the extent to which these innovations have changed how decisions about student progress are made is not clear. This paper describes a survey of 126 accredited allopathic U.S. medical schools to determine which information sources are used for decisions related to medical student progress and graduation. Respondents were asked to indicate up to three information sources used for seven specific decisions about student progress. The results indicate that multiple choice questions (MCQs) and faculty ratings remain the most frequently used information sources. Clinical skills education in the pre-clinical curriculum is the area with the broadest use of assessments for progress decisions. Several explanations are suggested for the primacy of MCQs and faculty ratings in student decisions, including familiarity for faculty and students, ease of implementation and the resources required for the adoption of other assessment strategies

Extensive microscale N isotopic heterogeneity in chondritic organic matter

Introduction: H and N isotopic anomalies (mainly excesses of D and 15N) in organic matter from primitive meteorites and IDPs suggest preservation of presolar molecular cloud material [1-3]. However, there have been very few spatially correlated H and N studies for either chondrites or IDPs [4, 5]. We report C and N isotopic imaging data for organic matter from four meteorites and three IDPs. D/H imaging data for many of the same samples are presented in [6, 7] and bulk organic isotope data in [8]

Extreme H isotopic anomalies in chondritic organic matter

Extract from introduction: We have conducted ionprobe (IMS6f and NanoSIMS) imaging studies of various samples for H, D, C, 14N and 15N. These will ultimately be correlated with micro-analytic techniques such as FIB/TEM or STXM/XANES. We analyzed matrix fragments from Bells (CM2), Al Rais (CR2) and Tagish Lake (unique) [2], high purity insoluble organic matter (IOM) [3] extracted from EET92042 (“EET”, CR2), Bells, Murchison (CM2), Allende (CV3), Krymka (LL3.1) and, for comparison, 3 IDPs

Nonmonotonic Evolution of the Blocking Temperature in Dispersions of Superparamagnetic Nanoparticles

We use a Monte Carlo approach to simulate the influence of the dipolar interaction on assemblies of monodisperse superparamagnetic ${\gamma}-Fe_{2}O_{3}$ nanoparticles. We have identified a critical concentration c*, that marks the transition between two different regimes in the evolution of the blocking temperature ($T_{B}$) with interparticle interactions. At low concentrations (c < c*) magnetic particles behave as an ideal non-interacting system with a constant $T_{B}$. At concentrations c > c* the dipolar energy enhances the anisotropic energy barrier and $T_{B}$ increases with increasing c, so that a larger temperature is required to reach the superparamagnetic state. The fitting of our results with classical particle models and experiments supports the existence of two differentiated regimes. Our data could help to understand apparently contradictory results from the literature.Comment: 13 pages, 7 figure

Conceptual design of a 1-MW CW X-band transmitter for planetary radar

A proposed conceptual design to increase the output power of an existing X-band radar transmitter used for planetary radar exploration from 365 kW to 1 MW CW is presented. The basic transmitter system requirements as dictated by the specifications for the radar are covered. The characteristics and expected performance of the high-power klystrons are considered, and the transmitter power amplifier system is described. Also included is the design of all of the associated high-power microwave components, the feed system, and the phase-stable exciter. The expected performance of the beam supply, heat exchanger, and monitor and control devices is also presented. Finally, an assessment of the state-of-the-art technology needed to meet system requirements is given and possible areas of difficulty are summarized

Control of Lambing Through Synchronization of Estrus and Induction of Parturition

The ability to program the time of birth for our livestock species offers several advantages to the producer. By concentrating lambing into a short defined period or periods it allows better utilization of labor and facilities. In addition, it should increase lamb survival since better supervision can be maintained for these specific periods. Furthermore, lambs are grouped more closely by age and can be more uniformly managed in such groups. Two trials (1983-84 and 1984-85) were conducted to study the effectiveness to prostaglandin F2α to synchronize estrus and flumethasone to induce parturition in a planned lambing program

Integrated Management of Reproduction in the Ewe

The ability to group lambing into a short predetermined period offers several desirable benefits to the producer. By concentrating lambing into a shorter period, one should be able to provide closer supervision and thereby increase survival. Also, lambs of similar age can be worked for castration, docking, vaccination, etc. as a group. Part-time producers may find it desirable to program lambing to coincide with available leave time if lambing can be confined to a reasonably short period. A trial was conducted during the 1982-83 breeding-lambing season to evaluate a combined program of synchronization of breeding and induction of lambing to achieve such a program

Relative Effectiveness of Estrous Synchronization Methods in the Ewe

The value of synchronization is in reducing the breeding period. Prostaglandin F2α (PGF) has been demonstrated to effectively synchronize ewes during the normal breeding season. Different methods of synchronizing estrus with PGF have been proposed. The purpose of this trial was to compare the relative effectiveness of singular PGF injection vs. a dual injection of PGF 10 days apart to a control for synchronizing estrus in the ewe during the normal breeding season