865 research outputs found
Potential utilization of scallop viscera for solid waste management and as feedstuff for swine
Waste management has been identified as a major problem
which will threaten the economic security of Florida's seafood
industry within the next ten years (1). One of the primary
concerns is treatment and disposal of solid wastes resulting from seafood processing.
Utilization of scallop viscera as silage, much like that
developed for waste fish and fish offal (3,4), could represent a practical solid waste treatment option which offers the additional benefit of a protein feed supplement for production of swine. (27pp.
Navigating to the Moon Along Low-Energy Transfers
This paper presents a navigation strategy to fly to the Moon along a Weak
Stability Boundary transfer trajectory. A particular strategy is devised to
ensure capture into an uncontrolled relatively stable orbit at the Moon. Both
uncertainty in the orbit determination process and in the control of the thrust
vector are included in the navigation analysis. The orbit determination process
is based on the definition of an optimal filtering technique that is able to
meet accuracy requirements at an acceptable computational cost. Three
sequential filtering techniques are analysed: an extended Kalman filter, an
Unscented Kalman filter and a Kalman filter based on high order expansions. The
analysis shows that only the unscented Kalman filter meets the accuracy
requirements at an acceptable computational cost. This paper demonstrates lunar
weak capture for all trajectories within a capture corridor defined by all the
trajectories in the neighbourhood of the nominal one, in state space. A minimum
f'v strategy is presented to extend the lifetime of the spacecraft around the
Moon. The orbit determination and navigation strategies are applied to the case
of the European Student Moon Orbiter
The structure and dynamics of young star clusters: King 16, NGC 1931, NGC 637 and NGC 189
In this paper, using 2MASS photometry, we study the structural and dynamical
properties of four young star clusters viz. King 16, NGC 1931, NGC 637 and NGC
189. For the clusters King 16, NGC 1931, NGC 637 and NGC 189, we obtain the
limiting radii of 7', 12', 6' and 5' which correspond to linear radii of 3.6
pc, 8.85 pc, 3.96 pc and 2.8 pc respectively. The reddening values
obtained for the clusters are 0.85, 0.65--0.85, 0.6 and 0.53 and their true
distances are 1786 pc, 3062 pc, 2270 pc and 912 pc respectively. Ages of the
clusters are 6 Myr, 4 Myr, 4 Myr and 10 Myr respectively. We compare their
structures, luminosity functions and mass functions () to the parameter to study the star
formation process and the dynamical evolution of these clusters. We find that,
for our sample, mass seggregation is observed in clusters or their cores only
when the ages of the clusters are comparable to their relaxation times (). These results suggest mass seggregation due to dynamical effects. The
values of , which characterise the overall mass functions for the
clusters are 0.96 0.11, 1.16 0.18, 0.55 0.14 and 0.66
0.31 respectively. The change in as a function of radius is a good
indicator of the dynamical state of clusters.Comment: Accepted for publication in Astrophysics & Space Scienc
Precambrian non-marine stromatolites in alluvial fan deposits, the Copper Harbor Conglomerate, upper Michigan
Laminated cryptalgal carbonates occur in the Precambrian Copper Harbor Conglomerate of northern Michigan, which was deposited in the Keweenawan Trough, an aborted proto-oceanic rift. This unit is composed of three major facies deposited by braided streams on a large alluvial-fan complex. Coarse clastics were deposited in braided channels, predominantly as longitudinal bars, whereas cross-bedded sandstones were deposited by migrating dunes or linguoid bars. Fine-grained overbank deposits accumulated in abandoned channels. Gypsum moulds and carbonate-filled cracks suggest an arid climate during deposition. Stromatolites interstratified with these clastic facies occur as laterally linked drapes over cobbles, as laterally linked contorted beds in mudstone, as oncolites, and as poorly developed mats in coarse sandstones. Stromatolites also are interbedded with oolitic beds and intraclastic conglomerates. Stromatolitic microstructure consists of alternating detrital and carbonate laminae, and open-space structures. Radial-fibrous calcite fans are superimposed on the laminae. The laminae are interpreted as algal in origin, whereas the origin of the radial fibrous calcite is problematic. The stromatolites are inferred to have grown in lakes which occupied abandoned channels on the fan surface. Standing water on a permeable alluvial fan in an arid climate requires a high water table maintained by high precipitation, or local elevation of the water table, possibly due to the close proximity of a lake. Occurrence of stromatolites in the upper part of the Copper Harbor Conglomerate near the base of the lacustrine Nonesuch Shale suggests that these depositional sites may have been near the Nonesuch Lake.Peer Reviewedhttp://deepblue.lib.umich.edu/bitstream/2027.42/72022/1/j.1365-3091.1983.tb00713.x.pd
Feedback-control of quantum systems using continuous state-estimation
We present a formulation of feedback in quantum systems in which the best
estimates of the dynamical variables are obtained continuously from the
measurement record, and fed back to control the system. We apply this method to
the problem of cooling and confining a single quantum degree of freedom, and
compare it to current schemes in which the measurement signal is fed back
directly in the manner usually considered in existing treatments of quantum
feedback. Direct feedback may be combined with feedback by estimation, and the
resulting combination, performed on a linear system, is closely analogous to
classical LQG control theory with residual feedback.Comment: 12 pages, multicol revtex, revised and extende
The torsion of a finite quasigroup quandle is annihilated by its order
We prove that if Q is a finite quasigroup quandle, then |Q| annihilates the
torsion of its homology. It is a classical result in reduced homology of finite
groups that the order of a group annihilates its homology. From the very
beginning of the rack homology (between 1990 and 1995) the analogous result was
suspected. The first general results in this direction were obtained
independently about 2001 by R.A.Litherland and S.Nelson, and P.Etingof and
M.Grana. In Litherland-Nelson paper it is proven that if (Q;*) is a finite
homogeneous rack (this includes quasigroup racks) then the torsion of homology
is annihilated by |Q|^n. In Etingof-Grana paper it is proven that if (X;A) is a
finite rack and N=|G^0_Q| is the order of a group of inner automorphisms of Q,
then only primes which can appear in the torsion of homology are those dividing
N (the case of connected Alexander quandles was proven before by T.Mochizuki).
The result of Litherland-Nelson is generalized by Niebrzydowski and Przytycki
and in particular, they prove that the torsion part of the homology of the
dihedral quandle R_3 is annihilated by 3. In Niebrzydowski-Przytycki paper it
is conjectured that for a finite quasigroup quandle, torsion of its homology is
annihilated by the order of the quandle. The conjecture is proved by T.Nosaka
for finite Alexander quasigroup quandles. In this paper we prove the conjecture
in full generality. For this version, we rewrote the Section 3 totally and
introduced the concept of the precubic homotopy. In Section 2, the main
addition is Corollary 2.2 which summarizes identities observed in the proof of
the main theorem as we use it later in Section 3.Comment: 13 pages, 1 figure; accepted for publication in Journal of Pure and
Applied Algebr
Depression: An actionable outcome for those at clinical high-risk
Comorbid diagnoses are common in youth who are at clinical high-risk (CHR) for developing psychosis, with depression being the most common. The aim of this paper is to examine depression over two years in a large sample of CHR youth who do not make the transition to psychosis, considering both categorical and dimensional ratings of depression severity. The sample consisted of 267 CHR youth who were followed for two years. Based on DSM-IV diagnoses over this time period, 100 CHR individuals never received a diagnosis of depression, 64 individuals continuously met criteria for depression, 92 individuals received a diagnosis of depression at one or more timepoints, and 11 participants had a diagnosis of depression only at 24-months. These groupings were supported by six-monthly ratings on the Calgary Depression Scale. The majority of this sample experienced a major depressive episode on more than one occasion, suggesting that depression and depressive symptoms identify a domain of substantial unmet clinical need. Recommendations are that depression in CHR youth and young adults should be monitored more frequently and that there is a need for clinical trials to address depression systematically in this vulnerable population
Dilepton mass spectra in p+p collisions at sqrt(s)= 200 GeV and the contribution from open charm
The PHENIX experiement has measured the electron-positron pair mass spectrum
from 0 to 8 GeV/c^2 in p+p collisions at sqrt(s)=200 GeV. The contributions
from light meson decays to e^+e^- pairs have been determined based on
measurements of hadron production cross sections by PHENIX. They account for
nearly all e^+e^- pairs in the mass region below 1 GeV/c^2. The e^+e^- pair
yield remaining after subtracting these contributions is dominated by
semileptonic decays of charmed hadrons correlated through flavor conservation.
Using the spectral shape predicted by PYTHIA, we estimate the charm production
cross section to be 544 +/- 39(stat) +/- 142(syst) +/- 200(model) \mu b, which
is consistent with QCD calculations and measurements of single leptons by
PHENIX.Comment: 375 authors from 57 institutions, 18 pages, 4 figures, 2 tables.
Submitted to Physics Letters B. v2 fixes technical errors in matching authors
to institutions. Plain text data tables for the points plotted in figures for
this and previous PHENIX publications are (or will be) publicly available at
http://www.phenix.bnl.gov/papers.htm
Inclusive cross section and double helicity asymmetry for \pi^0 production in p+p collisions at sqrt(s)=200 GeV: Implications for the polarized gluon distribution in the proton
The PHENIX experiment presents results from the RHIC 2005 run with polarized
proton collisions at sqrt(s)=200 GeV, for inclusive \pi^0 production at
mid-rapidity. Unpolarized cross section results are given for transverse
momenta p_T=0.5 to 20 GeV/c, extending the range of published data to both
lower and higher p_T. The cross section is described well for p_T < 1 GeV/c by
an exponential in p_T, and, for p_T > 2 GeV/c, by perturbative QCD. Double
helicity asymmetries A_LL are presented based on a factor of five improvement
in uncertainties as compared to previously published results, due to both an
improved beam polarization of 50%, and to higher integrated luminosity. These
measurements are sensitive to the gluon polarization in the proton, and exclude
maximal values for the gluon polarization.Comment: 375 authors, 7 pages, 3 figures. Submitted to Phys. Rev. D, Rapid
Communications. Plain text data tables for the points plotted in figures for
this and previous PHENIX publications are (or will be) publicly available at
http://www.phenix.bnl.gov/papers.htm
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