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A Dynamical Study of the Non-Star Forming Translucent Molecular Cloud MBM16: Evidence for Shear Driven Turbulence in the Interstellar Medium
(IOP Publishing, 1998-09) LaRosa, Theodore N.; Shore, Steven N.; Magnani, Loris Alberto
We present the results of a velocity correlation study of the high latitude cloud MBM16 using a fully sampled 12CO map, supplemented by new 13CO data. We find a correlation length of 0.4 pc. This is similar in size to the formaldehyde clumps described in our previous study. We associate this correlated motion with coherent structures within the turbulent flow. Such structures are generated by free shear flows. Their presence in this non-star forming cloud indicates that kinetic energy is being supplied to the internal turbulence by an external shear flow. Such large scale driving over long times is a possible solution to the dissipation problem for molecular cloud turbulence.
Landau–Ginzburg Vacua of String, M- and F-Theory at c = 12
(Elsevier [Commercial Publisher], 1998-12) Lynker, Monika; Schimmrigk, Rolf; Wisskirchen, Andreas
Theories in more than ten dimensions play an important role in understanding nonperturbative aspects of string theory. Consistent compactifications of such theories can be constructed via Calabi-Yau fourfolds. These models can be analyzed particularly efficiently in the Landau-Ginzburg phase of the linear σ-model, when available. In the present paper we focus on those σ-models which have both a Landau-Ginzburg phase and a geometric phase described by hypersurfaces in weighted projective five-space. We describe some of the pertinent properties of these models, such as the cohomology, the connectivity of the resulting moduli space, and mirror symmetry among the 1,100,055 configurations which we have constructed.
Evidence for nonequilibrium proton emission in a low-energy heavy-ion reaction
(American Physical Society, 1999) DeYoung, Paul A.; Hinnefeld, Jerry
Correlation functions for p-p, p-d, p-α, d-α, and α-α were measured for the 16O+27Al system at a beam energy of 72 MeV. The detector array was centered at laboratory angle of 20°. Compared to published data obtained at larger scattering angles, an unexpected dependence on angle is seen for the p-p channel. The observed anticorrelation is stronger at more forward angles, which suggests that correlation functions are sensitive to the specific reaction mechanisms producing the light-charged particles.
The Novel Signal Peptides, Pedibin and Hym-346, Lower Positional Value Thereby Enhancing Foot Formation in Hydra
(The Company of Biologists, 1999-01) Grens, Ann; Shimizu, Hiroshi; Hoffmeister, Sabine A. H.; Bode, Hans R.; Fujisawa, Toshitaka
Signaling molecules affecting patterning processes are usually proteins and rarely peptides. Two novel peptides, pedibin and Hym-346, that are closely related to one another have been isolated from Hydra vulgaris and Hydramagnipapillata. Several experiments indicate that both cause a reduction in the positional value gradient, the principle patterning process governing the maintenance of form in the adult hydra. The peptides cause an increase in the rate of foot regeneration following bisection of the body column. Treatment of animals with either peptide for an extended period of time resulted in an apical extension of the range of expression of CnNk-2 along the body column. Such an extension is correlated with a decrease in positional value. Transplantation of tissue treated with Hym-346 results in an increase in the fraction forming feet, and aggregates derived from Hym-346 tissue form more feet and fewer heads. The latter two experiments provide a direct measure of the lowering of positional value in the treated tissue. These results suggest that peptides play signaling roles in patterning processes in cnidaria and, plausibly, in more complex metazoans as well. Key words: Hydra, Pedibin/Hym-346, Foot formation
Loops and Semidirect Products
(Communications in Algebra 28 (2000), no. 9, 4137–4164., 1999-07) Kinyon, Michael; Jones, Oliver
"In this paper we study semidirect products of loops with groups. This is a generalization of the familiar semidirect product of groups." Discusses extensive information concerning semidirect products and transversal decompositions of various kinds of loops and left loops.
The Electrical Properties of the Anterior Stomach of the Larval Mosquito (Aedes Aegypti)
(The Company of Biologists, 2000) Clark, Thomas M.; Koch, Alan; Moffett, David F.
The electrical properties of the anterior stomach of the larval mosquito (Aedes aegypti) were determined. At late times after cannulation, the intraluminal space constant was 936 mm, which is almost as long as the isolated tissue itself. At this time, the resistance of the apical cell membranes dominates the transcellular resistance; it is approximately 14 times the resistance of the basal cell membrane. Two physiologically distinct epithelial cell types were identified. One type has a stable basal potential of approximately 65 mV and responds to 5-hydroxytryptamine with hyperpolarization. The second cell type initially shows a basal potential of 100mV. However, this basal potential decays in the first few minutes in parallel with the decay of the transintestinal potential. This latter cell type does not respond to 5-hydroxytryptamine. Key words: mosquito, Aedes aegypti, midgut, larva, intracellular potential, 5-hydroxytryptamine.
Hyper-Special Valued Lattice-Ordered Groups
(De Gruyter, 2000) Darnel, Michael R., 1952-; Martinez, Jorge
A lattice-ordered group G is hyper-special valued if it lies in the largest torsion class which is contained in the class of special-valued lattice-ordered groups. This is precisely the class of lattice-ordered g oups G such that for each g A G, every l-homomorphic image K of the principal convex l-subgroup generated by g has the feature that each 0 < x A K is the supremum of pairwise disjoint special elements. It is shown in this article that if G is hyper-special valued, then for each g ∈ G, the space of values Y(g) of g is a compact scattered space. This property naturally gives meaning to the notion of an α-special value of g: this is a value which corresponds to an isolated point of the α-th remainder in the Cantor-Bendixson sequence of Y(g). It is shown that, for each ordinal α, the set of a-special values of G forms a disjoint union of chains, which is at once an order ideal and a dual order ideal of the root system of all values of G. If G is projectable, then in addition the set of special values of G is also a disjoint union of chains which is an order ideal and a dual order ideal. An archimedean lattice-ordered group G with weak order unit u > 0, given its Yosida representation, such that u≡1 is hyper-special valued if and only if (a) G is projectable, (b) the Yosida space Y is scattered, and (c) for each g ∈ G the image of the function g has finitely many ∞'s as well as finitely many accumulations of 0.
Coexistence of Mutualists and Antagonists: Exploring the Impact of Cheaters on the Yucca - Yucca Moth Mutualism
(Oecologia, 2001) Marr, Deborah L.; Brock, Marcus T.; Pellmyr, Olle
Abstract Mutualists and non-mutualistic cheaters commonly coexist, but the effect of mutualist-cheater interactions on the evolution and stability of mutualisms or persistence of cheater populations is not well understood. Yuccas and yucca moths are an example of an obligate mutualism in which cheaters are frequently present. Larvae of both pollinators and cheaters eat developing yucca seeds, but cheaters no longer pollinate and rely on the mutualist species for seed availability. In this study we focus on interactions between the cheater Tegeticula intermedia and the pollinator T. yuccasella in fruits of the host Yucca filamentosa. We examined the effect of pollinator and cheater density on larval mass and larval mortality, the effect of fruit mass on larval interactions, and the degree of variability in pollinator-cheater interactions across 3 years. This study was done in a natural population to determine whether these two larval species affect each other under natural conditions. Genetic markers (both protein electrophoresis and DNA sequencing) were used to identify the larvae to species. We found no correlation between larval number and mortality for either pollinators or cheaters. Furthermore, pollinator mass was not correlated with number of cheater larvae per fruit in any year. Mass of cheater larvae was not correlated with number of pollinator larvae per fruit in two of three years; in one year, there was a negative correlation between number of pollinator larvae on mass of cheater larvae only in small fruits. Our results suggest that larval competition between species is weak and asymmetric; when it occurs, cheater larvae incur the cost. The number of cheaters and pollinators per fruit was negatively correlated in two of three years. The lack of a positive correlation in number of cheater and pollinator larvae per fruit may contribute to lowering the potential for seed competition among larvae. In addition, larval density per fruit differed across years by as much as 30%. However, this degree of difference was apparently not enough to cause seed limitation because no effect of pollinator larvae on either mass or mortality of cheater larvae was detected in years with the highest larval densities per fruit. In contrast to the weak effects of pollinator-cheater interactions, fruit mass accounted for much of the variation in number and mass of both pollinator and cheater larvae within and across years. Larger fruits generally had heavier and higher numbers of larvae compared to smaller fruits. Overall, in this population at least within the time period studied, pollinators and cheaters coexisted with little conflict in fruit. This result is consistent with the hypothesis that the recent rapid radiation of species in the T. yuccasella complex may be explained in part by the ability of multiple pollinator species (some of whom have become cheaters) to use fruits without severe competition. Keywords: Mutualism, Antagonism, Species coexistence, Stability of cheaters, Plant-pollinator interactions
Proton elastic scattering from 7Be at low energies.
(American Physical Society, 2001-01) Rogachev, Grigoriy V.; Hinnefeld, Jerry
The elastic scattering of protons on 7Be has been measured in the energy region from 1-3.3 MeV via the thick-target technique. The data conclusively demonstrate the existence of a 2− state at an excitation energy of approximately 3.5 MeV in 8B, and rule out a predicted 1+ state near 1.4 MeV. The relevance of these results for the 7Be (p,γ) reaction, of interest in solar neutrino physics, is discussed.
Horizontal and Vertical Movements of Juvenile Bluefin Tuna (Thunnus thynnus), in Relation to Oceanographic Conditions of the Western North Atlantic, Determined with Ultrasonic Telemetry
(National Marine Fisheries Service, 2001-07) Brill, Richard Walter; Lutcavage, Molly; Metzger, Greg; Bushnell, Peter G. (Peter Gerald); Arendt, Michael D., 1974-; Lucy, Jon; Watson, Cheryl Lynn; Foley, David G.
We employed ultrasonic transmitters to follow (for up to 48 h) the horizontal and vertical movements of five juvenile (6.8–18.7 kg estimated body mass) bluefin tuna (Thunnus thynnus) in the western North Atlantic (off the eastern shore of Virginia). Our objective was to document the fishes’ behavior and distribution in relation to oceanographic conditions and thus begin to address issues that currently limit population assessments based on aerial surveys. Estimation of the trends in adult and juvenile Atlantic bluefin tuna abundance by aerial surveys, and other fishery-independent measures, is considered a priority. Juvenile bluefin tuna spent the majority of their time over the continental shelf in relatively shallow water (generally less then 40 m deep). Fish used the entire water column in spite of relatively steep vertical thermal gradients (≈24°C at the surface and ≈12°C at 40 m depth), but spent the majority of their time (≈90%) above 15 m and in water warmer then 20°C. Mean swimming speeds ranged from 2.8 to 3.3 knots, and total distance covered from 152 to 289 km (82–156 nmi). Because fish generally remained within relatively con-fined areas, net displacement was only 7.7–52.7 km (4.1–28.4 nmi). Horizontal movements were not correlated with sea surface temperature. We propose that it is unlikely that juvenile bluefin tuna in this area can detect minor horizontal temperature gradients (generally less then 0.5°C/km) because of the steep vertical temperature gradients (up to ≈0.6°C/m) they experience during their regular vertical movements. In contrast, water clarity did appear to influence behavior because the fish remained in the intermediate water mass between the turbid and phytoplankton-rich plume exiting Chesapeake Bay (and similar coastal waters) and the clear oligotrophic water east of the continental shelf.
Evolution of Li, Be and B in the Galaxy
(American Astronomical Society, 2001-10) Valle, Giada; Ferrini, Federico; Galli, Daniele; Shore, Steven N.
In this paper we study the production of Li, Be and B nuclei by Galactic cosmic ray spallation processes. We include three kinds of processes: (i ) spallation by light cosmic rays impinging on interstellar CNO nuclei (direct processes); (ii ) spallation by CNO cosmic ray nuclei impinging on interstellar p and 4He (inverse processes); and (iii ) α–α fusion reactions. The latter dominate the production of 6,7Li. We calculate production rates for a closed-box Galactic model, verifying the quadratic dependence of the Be and B abundances for low values of Z. These are quite general results and are known to disagree with observations. We then show that the multi-zone multi-population model we used previously for other aspects of Galactic evolution produces quite good agreement with the linear trend observed at low metallicities without fine tuning. We argue that reported discrepancies between theory and observations do not represent a nucleosynthetic problem, but instead are the consequences of inaccurate treatments of Galactic evolution.
A Generalization of Moufang and Steiner Loops
(Springer, 2001-11) Kinyon, Michael; Kunen, Kenneth; Phillips, Jon D.
We study a variety of loops, RIF, which arise naturally from considering inner mapping groups, and a somewhat larger variety, ARIF. All Steiner and Moufang loops are RIF, and all flexible C-loops are ARIF. All ARIF loops are diassociative.
New developments and recent results in nuclear astrophysics at Louvain-la-Neuve
(American Physical Society, 2002-04) Cherubini, S.; Hinnefeld, Jerry
Nuclear astrophysics using radioactive nuclear beams is one of the major research topics in Louvain-la-Neuve. Recently, experiment aiming at the measurement of (α,γ), and (α, p) reactions have been performed. The 15O(α,γ)19Ne reaction was studied using an indirect method based on the study of the 18Ne(d, p)19Ne*. Preliminary results of a new analysis of this experiment are presented here. The new mass recoil separator ARES, coupled to the new cyclotron CYCLONE-44, is now operational. The ARES project status and results of performance tests are reported here.
Direct Evidence for Neutrino Flavor Transformation from Neutral-Current Interactions in the Sudbury Neutrino Observatory
(American Physical Society, 2002-07) Ahmad, Q. R.; Levine, Ilan
Observations of neutral-current n interactions on deuterium in the Sudbury Neutrino Observatory are reported. Using the neutral current (NC), elastic scattering, and charged current reactions and assuming the standard 8B shape, the ne component of the 8B solar flux is Φe = 1.76 +0.05 -0.05 (stat)+0.09 -0.09(syst) x 10^6 cm^-2 s^-1 for a kinetic energy threshold of 5 MeV. The non-ve component is Φe = 3.41 +0.45 -0.45(stat) +0.48 -0.45(syst) x 10^6 cm^-2 s^-1, 5.3o greater than zero, providing strong evidence for solar ve flavor transformation. The total flux measured with the NC reaction is ΦNC = 5.09 +0.44 -0.43(stat) =0.46 -0.43(syst) x 10^6 cm^-2 s^-1, consistent with solar models.
Final state interaction or a 3H excited state?
(American Physical Society, 2003) Rogachev, Grigoriy V.; Hinnefeld, Jerry
An inclusive a-particle spectrum from the 1H(6He,a) reaction has been measured at a 6He laboratory energy of 23.9 MeV. A resonancelike structure is observed at an a-particle lab energy of about 20 MeV, which corresponds to an energy of End50.6 MeV in the n-d channel. An analysis of the spectrum shows that it cannot be explained by the effect of binary final-state interactions. The hypotheses that this structure represents ~a! a new excited state of tritium or ~b! a three-body final-state interaction are discussed.
Complex Multiplication Symmetry of Black Hole Attractors
(Elsevier, 2003) Lynker, Monika; Periwal, Vipul; Schimmrigk, Rolf
We show how Moore’s observation, in the context of toroidal compactifications in type IIB string theory, concerning the complex multiplication structure of black hole attractor varieties, can be generalized to Calabi-Yau compactifications with finite fundamental groups. This generalization leads to an alternative general framework in terms of motives associated to a Calabi-Yau variety in which it is possible to address the arithmetic nature of the attractor varieties in a universal way via Deligne’s period conjecture.
Archvillin, a muscle-specific isoform of supervillin, is an early expressed component of the costameric membrane skeleton
(The Company of Biologists, 2003-02) Oh, Sang W.; Pope, Robert K.; Smith, Kelly P.; Crowley, Jessica L.; Nebl, Thomas; Lawrence, Jeanne B.; Luna, Elizabeth J.
The membrane skeleton protein supervillin binds tightly to both F-actin and membranes and can potentiate androgen receptor activity in non-muscle cells. We report that muscle, which constitutes the principal tissue source for supervillin sequences, contains a ~250 kDa isoform of supervillin that localizes within nuclei and with dystrophin at costameres, regions of F-actin membrane attachment in skeletal muscle. The gene encoding this protein, ‘archvillin’ (Latin, archi; Greek, árchos; ‘principal’ or ‘chief’), contains an evolutionarily conserved, muscle-specific 5¢ leader sequence. Archvillin cDNAs also contain four exons that encode ~47 kDa of additional muscle-specific protein sequence in the form of two inserts within the function-rich N-terminus of supervillin. The first of these muscle-specific inserts contains two conserved nuclear targeting signals in addition to those found in sequences shared with supervillin. Archvillin, like supervillin, binds directly to radiolabeled F-actin and co-fractionates with plasma membranes. Colocalization of archvillin with membraneassociated actin filaments, non-muscle myosin II, and – to a lesser extent – vinculin was observed in myoblasts. Striking localizations of archvillin protein and mRNA were observed at the tips of differentiating myotubes. Transfected protein chimeras containing archvillin insert sequences inhibited myotube formation, consistent with a dominant-negative effect during early myogenesis. These data suggest that archvillin is among the first costameric proteins to assemble during myogenesis and that it contributes to myogenic membrane structure and differentiation. Keywords: Costamere, Sarcolemma, Membrane skeleton, C2C12 cells, 50MB-1 cells
Effects of Consumption of Juniper (Juniperus monosperma) on Cost of Thermoregulation in the Woodrats Neotoma albigula and Neotoma stephensi at Different Acclimation Temperatures
(University of Chicago Press, 2003-06) McLister, James D.; Sorensen, Jenifer S.; Dearing, M. Denise
A study was done to test whether toxic plants that occur naturally in the diet affect thermoregulation in mammalian herbivores. The woodrats Neotoma albigula and Neotoma stephensi both consume juniper (Juniperus monosperma), a plant with high levels of toxic compounds. Body temperature (Tb), basal metabolic rate (BMR), and the minimum cost of thermogenesis (Cmin) were measured for both species on control and juniper diets following warm (25°C) and cold (18°C) acclimation. In N. albigula, diet had no uniform effect on Tb, BMR, or Cmin, but -temperature interaction effects on Tb diet x acclimation and Cmin were highly significant (P ! 0.005). For thermoregulation at 15°C, juniper consumption increased the metabolic cost for warm-acclimated N. albigula by 50% but decreased the metabolic cost in cold-acclimated N. albigula by 24%. In N. stephensi, diet significantly affected Tb and Cmin (P ! 0.05), but there were no significant diet x acclimation-temperature interaction effects. For thermoregulation at 15°C, juniper consumption increased the metabolic cost for warm-acclimated N. stephensi by 33% but had no significant effect on metabolic cost in cold-acclimated N. stephensi. Keywords: Body temperature -- Regulation; One-seed juniper; White-throated wood rat; Neotoma
Measurement of the Total Active 8B Solar Neutrino Flux at the Sudbury Neutrino Observatory with Enhanced Neutral Current Sensitivity
(American Physical Society, 2004) Ahmed, S. N.; Levine, Ilan
The Sudbury Neutrino Observatory (SNO) has precisely determined the total active (nu_x) 8B solar neutrino flux without assumptions about the energy dependence of the nu_e survival probability. The measurements were made with dissolved NaCl in the heavy water to enhance the sensitivity and signature for neutral-current interactions. The flux is found to be 5.21 +/- 0.27 (stat) +/- 0.38 (syst) x10^6 cm^{-2}s^{-1}, in agreement with previous measurements and standard solar models. A global analysis of these and other solar and reactor neutrino results yields Delta m^{2} = 7.1^{+1.2}_{-0.6}x10^{-5} ev^2 and theta = 32.5^{+2.4}_{-2.3} degrees. Maximal mixing is rejected at the equivalent of 5.4 standard deviations
Constraints on Nucleon Decay via “Invisible” Modes from the Sudbury Neutrino Observatory
(Physical Review, 2004) Ahmed, S. N.; Anthony, A. E.; Beier, E. W.; Bellerive, A.; Biller, S. D.; Boger, J.; Boulay, M. G.; Bowler, M. G.; Bowles, T. J.; Brice, S. J.; Bullard, T. V.; Chan, Y. D.; Chen, M.; Chen, X.; Cleveland, B. T.; Cox, G. A.; Dai, X.; Dalnoki-Veress, F.; Doe, P. J.; Dosanjh, R. S.; Doucas, G.; Dragowsky, M. R.; Duba, C. A.; Duncan, F. A.; Dunford, M.; Dunmore, J. A.; Earle, E. D.; Elliott, S. R.; Evans, H. C.; Ewan, G. T.; Farine, J.; Fergani, H.; Fleurot, F.; Formaggio, J. A.; Fowler, M. M.; Frame, K.; Frati, W.; Fulsom, B. G.; Gagnon, N.; Graham, K.; Grant, D. R.; Hahn, R. L.; Hall, J. C.; Hallin, A. L.; Hallman, E. D.; Hamer, A. S.; Handler, W. B.; Hargrove, C. K.; Harvey, P. J.; Hazama, R.; Heeger, K. M.; Heintzelman, W. J.; Heise, J.; Helmer, R. L.; Hemingway, R. J.; Hime, A.; Howe, M. A.; Jagam, P.; Jelley, N. A.; Klein, J. R.; Kos, M. S.; Krumins, A. V.; Kutter, T.; Kyba, C. C. M.; Labranche, H.; Lange, R.; Law, J.; Lawson, I. T.; Lesko, K. T.; Leslie, J. R.; Levine, Ilan; Luoma, S.; MacLellan, R.; Majerus, S.; Mak, H. B.; Maneira, J.; Marino, A. D.; McCauley, N.; McDonald, A. B.; McGee, S.; McGregor, G.; Mifflin, C.; Miknaitis, K. K. S.; Miller, G. G.; Moffat, B. A.; Nally, C. W.; Neubauer, M. S.; Nickel, B. G.; Noble, A. J.; Norman, E. B.; Oblath, N. S.; Okada, C. E.; Ollerhead, R. W.; Orrell, J. L.; Oser, S. M.; Ouellet, C.; Peeters, S. J. M.; Poon, A. W. P.; Robertson, B. C.; Robertson, R. G. H.; Rollin, E.; Rosendahl, S. S. E.; Rusu, V. L.; Schwendener, M. H.; Simard, O.; Simpson, J. J.; Sims, C. J.; Sinclair, D.; Skensved, P.; Smith, M. W. E.; Starinsky, N.; Stokstad, R. G.; Stonehill, L. C.; Tafirout, R.; Takeuchi, Y.; Tešić, G.; Thomson, M.; Thorman, M.; Van Berg, R.; Van de Water, R. G.; Virtue, C. J.; Wall, B. L.; Waller, D.; Waltham, C. E.; Wan Chan Tseung, H.; Wark, D. L.; West, N.; Wilhelmy, J. B.; Wilkerson, J. F.; Wilson, J. R.; Wittich, P.; Wouters, J. M.; Yeh, M.; Zuber, K.
Data from the Sudbury Neutrino Observatory have been used to constrain the lifetime for nucleon decay to “invisible” modes, such as n -> 3v. The analysis was based on a search for y-rays from the de-excitation of the residual nucleus that would result from the disappearance of either a proton or neutron from ^16O. A limit of t inv > 2×1029 years is obtained at 90% confidence for either neutron or proton decay modes. This is about an order of magnitude more stringent than previous constraints on invisible proton decay modes and 400 times more stringent than similar neutron modes.

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