Pre-resonance Raman spectra of some simple gases

The pre-resonance Raman spectra of SO2, N2O, and H2S were investigated using the 4880 A, 4727 A, and 4579 A lines of the argon ion laser. Although these molecules have electronic absorption bands in the near ultraviolet, none exhibit any pre-resonance enhancement within our experimental error of + or - 10%. Possible explanations taking into account the current theories for resonance Raman are discussed

Francis Daniels Moore: one of the brightest minds in the surgical field.

Francis Daniels Moore was a pioneer ahead of his time who made numerous landmark contributions to the field of surgery, including the understanding of metabolic physiology during surgery, liver and kidney transplant, and the famous Study on Surgical Services of the United States (SOSSUS) report of 1975 that served for decades as a guideline for development of surgical residencies. He was the epitome of what a physician should be, a compassionate and dedicated surgeon, innovative scientist, and a medical professional dedicated to quality medical education across all specialties

Rhythm and Vowel Quality in Accents of English

In a sample of 27 speakers of Scottish Standard English two notoriously variable consonantal features are investigated: the contrast of /m/ and /w/ and non-prevocalic /r/, the latter both in terms of its presence or absence and the phonetic form it takes, if present. The pattern of realisation of non-prevocalic /r/ largely confirms previously reported findings. But there are a number of surprising results regarding the merger of /m/ and /w/ and the loss of non-prevocalic /r/: While the former is more likely to happen in younger speakers and females, the latter seems more likely in older speakers and males. This is suggestive of change in progress leading to a loss of the /m/ - /w/ contrast, while the variation found in non-prevocalic /r/ follows an almost inverse sociolinguistic pattern that does not suggest any such change and is additionally largely explicable in language-internal terms. One phenomenon requiring further investigation is the curious effect direct contact with Southern English accents seems to have on non-prevocalic /r/: innovation on the structural level (i.e. loss) and conservatism on the realisational level (i.e. increased incidence of [r] and [r]) appear to be conditioned by the same sociolinguistic factors

The geometry of reaction norms yields insights on classical fitness functions for Great Lakes salmon.

Life history theory examines how characteristics of organisms, such as age and size at maturity, may vary through natural selection as evolutionary responses that optimize fitness. Here we ask how predictions of age and size at maturity differ for the three classical fitness functions-intrinsic rate of natural increase r, net reproductive rate R0, and reproductive value Vx-for semelparous species. We show that different choices of fitness functions can lead to very different predictions of species behavior. In one's efforts to understand an organism's behavior and to develop effective conservation and management policies, the choice of fitness function matters. The central ingredient of our approach is the maturation reaction norm (MRN), which describes how optimal age and size at maturation vary with growth rate or mortality rate. We develop a practical geometric construction of MRNs that allows us to include different growth functions (linear growth and nonlinear von Bertalanffy growth in length) and develop two-dimensional MRNs useful for quantifying growth-mortality trade-offs. We relate our approach to Beverton-Holt life history invariants and to the Stearns-Koella categorization of MRNs. We conclude with a detailed discussion of life history parameters for Great Lakes Chinook Salmon and demonstrate that age and size at maturity are consistent with predictions using R0 (but not r or Vx) as the underlying fitness function

Programmability and Performance of Parallel ECS-based Simulation of Multi-Agent Exploration Models

While the traditional objective of parallel/distributed simulation techniques has been mainly in improving performance and making very large models tractable, more recent research trends targeted complementary aspects, such as the “ease of programming”. Along this line, a recent proposal called Event and Cross State (ECS) synchronization, stands as a solution allowing to break the traditional programming rules proper of Parallel Discrete Event Simulation (PDES) systems, where the application code processing a specific event is only allowed to access the state (namely the memory image) of the target simulation object. In fact with ECS, the programmer is allowed to write ANSI-C event-handlers capable of accessing (in either read or write mode) the state of whichever simulation object included in the simulation model. Correct concurrent execution of events, e.g., on top of multi-core machines, is guaranteed by ECS with no intervention by the programmer, who is in practice exposed to a sequential-style programming model where events are processed one at a time, and have the ability to access the current memory image of the whole simulation model, namely the collection of the states of any involved object. This can strongly simplify the development of specific models, e.g., by avoiding the need for passing state information across concurrent objects in the form of events. In this article we investigate on both programmability and performance aspects related to developing/supporting a multi-agent exploration model on top of the ROOT-Sim PDES platform, which supports ECS

Synthesis and characterisation of gel-derived mullite precursors from rice husk silica

The sol-gel synthesis and characterization of mullite precursor derived from rice husk silica and aluminum nitrate hydrate [(Al(NO3)3·9H2O] has been investigated. The samples were characterized using Fourier transform infrared (FTIR) spectroscopy, X-ray diffraction (XRD) coupled with Rietveld analysis, and scanning electron microscopy (SEM). FTIR results showed the presence of Si-O-Si, Al-O-Al, and Si-O-Al functional groups, which were associated with mullite, corundum, quartz, and cristobalite, as verified by XRD analysis. It is concluded that mullite formation started at 1150 °C, and its abundance increased rapidly with an increase in temperature from 1150 to 1350 °C, resulting in increased phase content from 30.9 to 67.7 wt%. Although mullite was formed at a low temperature, the complete reaction between corundum and silica to form mullite was not achieved. This finding demonstrated that rice husk silica is a potential alternative raw material for the production of mullite ceramic

Representations of the Canonical group, (the semi-direct product of the Unitary and Weyl-Heisenberg groups), acting as a dynamical group on noncommuting extended phase space

The unitary irreducible representations of the covering group of the Poincare group P define the framework for much of particle physics on the physical Minkowski space P/L, where L is the Lorentz group. While extraordinarily successful, it does not provide a large enough group of symmetries to encompass observed particles with a SU(3) classification. Born proposed the reciprocity principle that states physics must be invariant under the reciprocity transform that is heuristically {t,e,q,p}->{t,e,p,-q} where {t,e,q,p} are the time, energy, position, and momentum degrees of freedom. This implies that there is reciprocally conjugate relativity principle such that the rates of change of momentum must be bounded by b, where b is a universal constant. The appropriate group of dynamical symmetries that embodies this is the Canonical group C(1,3) = U(1,3) *s H(1,3) and in this theory the non-commuting space Q= C(1,3)/ SU(1,3) is the physical quantum space endowed with a metric that is the second Casimir invariant of the Canonical group, T^2 + E^2 - Q^2/c^2-P^2/b^2 +(2h I/bc)(Y/bc -2) where {T,E,Q,P,I,Y} are the generators of the algebra of Os(1,3). The idea is to study the representations of the Canonical dynamical group using Mackey's theory to determine whether the representations can encompass the spectrum of particle states. The unitary irreducible representations of the Canonical group contain a direct product term that is a representation of U(1,3) that Kalman has studied as a dynamical group for hadrons. The U(1,3) representations contain discrete series that may be decomposed into infinite ladders where the rungs are representations of U(3) (finite dimensional) or C(2) (with degenerate U(1)* SU(2) finite dimensional representations) corresponding to the rest or null frames.Comment: 25 pages; V2.3, PDF (Mathematica 4.1 source removed due to technical problems); Submitted to J.Phys.

Characteristics of aluminosilicates prepared from rice husk silica and aluminum metal

This study investigated use of the electrochemical method to prepare aluminosilicates from rice husk silica and aluminum metal. The aluminosilicate precursors were characterized using Scanning Electron Microscopy/Energy Dispersive X-ray spectroscopy (SEM/EDX), Fourier Transform Infrared (FTIR) spectroscopy, and X-ray Diffraction spectroscopy (XRD). The precursors were subsequently sintered at 700–1400 °C and their microstructures and phase compositions were characterized. Results showed that the proposed method could be used to prepare aluminosilicates with high uniformity in terms of surface morphology and the particle size with mullite and quartz as the major phases formed

Twin paradox and space topology

If space is compact, then a traveller twin can leave Earth, travel back home without changing direction and find her sedentary twin older than herself. We show that the asymmetry between their spacetime trajectories lies in a topological invariant of their spatial geodesics, namely the homotopy class. This illustrates how the spacetime symmetry invariance group, although valid {\it locally}, is broken down {\it globally} as soon as some points of space are identified. As a consequence, any non--trivial space topology defines preferred inertial frames along which the proper time is longer than along any other one.Comment: 6 pages, latex, 3 figure

Thermal and Magnetorotational Instability in the ISM: Two-Dimensional Numerical Simulations

The structure and dynamics of diffuse gas in the Milky Way and other disk galaxies may be strongly influenced by thermal and magnetorotational instabilities (TI and MRI) on scales of about 1-100 pc. We initiate a study of these processes, using two-dimensional numerical hydrodynamic and magnetohydrodynamic (MHD) simulations with conditions appropriate for the atomic interstellar medium (ISM). We demonstrate, consistent with previous work, that nonlinear development of ``pure TI'' produces a network of filaments that condense into cold clouds at their intersections, yielding a distinct two-phase warm/cold medium within about 20 Myr. TI-driven turbulent motions of the clouds saturate at subsonic amplitudes for uniform initial P/k=2000 K cm^-3. MRI has previously been studied in near-uniform media; our simulations include both TI+MRI models, which begin from uniform-density conditions, and cloud+MRI models, which begin with a two-phase cloudy medium. Both the TI+MRI and cloud+MRI models show that MRI develops within a few galactic orbital times, just as for a uniform medium. The mean separation between clouds can affect which MRI mode dominates the evolution. Provided intercloud separations do not exceed half the MRI wavelength, we find the MRI growth rates are similar to those for the corresponding uniform medium. This opens the possibility, if low cloud volume filling factors increase MRI dissipation times compared to those in a uniform medium, that MRI-driven motions in the ISM could reach amplitudes comparable to observed HI turbulent linewidths.Comment: 42 pages, 15 figures, accepted for publication in ApJ; For better postscript figures and mpeg animations, see http://www.astro.umd.edu/~rpiontek/papers/ti_mri_2D.htm