Showing papers on "Saturation (graph theory) published in 2008"

A Swift gaze into the 2006 March 29th burst forest of SGR 1900+14

Abstract: We report on the intense burst ``forest'' recorded on 2006 March 29 which lasted for ~30s. More than 40 bursts were detected both by BAT and by XRT, seven of which are rare intermediate flares (IFs): several times 10^{42} ergs were released. The BAT data were used to carry out time-resolved spectroscopy in the 14-100keV range down to 8ms timescales. This unique dataset allowed us to test the magnetar model predictions such as the magnetically trapped fireball and the twisted magnetosphere over an unprecedented range of fluxes and with large statistics (in terms of both photons and IFs). We confirmed that a two blackbody component fits adequately the time-resolved and integrated spectra of IFs. However, Comptonization models give comparable good reduced chi^2. Moreover, we found: i) a change of behavior, around ~10^{41} erg/s, above which the softer blackbody shows a sort of saturation while the harder one still grows to a few times 10^{41} erg/s; ii) a rather sharp correlation between temperature and radii of the blackbodies (R^2 prop kT^{-3}), which holds for the most luminous parts of the flares (approximately for L_{tot} > 10^{41} erg/s). Within the magnetar model, the majority of these findings can be accounted for in terms of thermalised emission from the E-mode and O-mode photospheres. Interestingly, the maximum observed luminosity coming from a region of ~15km matches the magnetic Eddington luminosity at the same radius, for a surface dipole field of ~8 x 10^{14} G (virtually equal to the one deduced from the spindown of SGR 1900+14).

Particulate matter chemistry and dynamics in the Twilight Zone at VERTIGO ALOHA and K2 Sites

Abstract: Understanding particle dynamics in the 'Twilight Zone' is critical to prediction of the ocean's carbon cycle. As part of the VERTIGO (VERtical Transformations In the Global Ocean) project, this rarely sampled regime extending from the base of the euphotic layer to 1000 m, was characterized by double-paired day/night Multiple Unit Large Volume in-situ Filtration System (MULVFS) deployments and by {approx}100 high-frequency CTD/transmissometer/turbidity sensor profiles. VERTIGO studies lasting three weeks, contrasted oligotrophic station ALOHA (22.75{sup o}N 158{sup o}W), sampled in June-July 2004, with a biologically productive location (47{sup o}N 161{sup o}E) near station K2 in the Oyashio, occupied July-August 2005. Profiles of major and minor particulate components (C{sub org}, N, P, Ca, Si, Sr, Ba, Mn) in 51 {micro}m size fractions, in-water optics, neutrally buoyant sediment trap (NBST) fluxes, and zooplankton data were intercompared. MULVFS total C{sub org} and C-Star particle beam attenuation coefficient (C{sub P}) were consistently related at both sites with a 27 {micro}M m{sup -1} conversion factor. 26 At K2, C{sub P} profiles further showed a multitude of transient spikes throughout the water column and spike abundance profiles closely paralleled the double peaked abundance profiles of zooplankton. Also at K2, copepods contributed {approx}40% and 10%, night and day, respectively to >51 {micro}m C{sub org} of MULVFS samples in the mixed layer, but few copepods were collected in deeper waters; however, non-swimming radiolarians were quantitatively sampled. A recent hypothesis regarding POC differences between pumps and bottles is examined in light of these results. Particulate >51 {micro}m C{sub org}, N, and P at both ALOHA and K2 showed strong attenuation with depth at both sites. Notable at ALOHA were unusually high levels of >51 {micro}m Sr (up to 4 nM) in the mixed layer, a reflection of high abundances of SrSO{sub 4} precipitating Acantharia. Notable at K2 were major changes in water column inventories of many particulate components to 700 m over 10 days. Carbon mass balance, with the consideration of particle inventory changes included, indicated that over 98% and 96% of primary produced C{sub org} was remineralized shallower than 500 m at ALOHA and K2, respectively. Production of CaCO3 was estimated to be {approx}0.06, 0.89 and 0.02 mmols m{sup -2} d{sup -1} at ALOHA and at K2 during two separate week long study periods, respectively. Similarly, Si production was estimated to be {approx}0.08, 10.7, and 4.2 mols m{sup -2} d{sup -1}. An estimated 50% and 65% of produced Si was remineralized by 500m at ALOHA and K2, respectively. Little carbonate dissolution was seen in the upper 500 m at ALOHA, a reflection of 400% super saturation of surface waters and the 700 m deep saturation horizon. Over 92% of produced CaCO{sub 3} was dissolved shallower than 500 m at K2 and biological enhancement of dissolution was readily apparent in waters above the 200 m calcite saturation horizon.

Kinetics of heterogeneous bubble nucleation in rhyolitic melts: implications for the number density of bubbles in volcanic conduits and for pumice textures

Abstract: We performed decompression experiments to simulate the ascent of a phenocryst-bearing rhyolitic magma in a volcanic conduit The starting materials were bubble-free rhyolites water-saturated at 200 MPa–800°C under oxidizing conditions: they contained 60 wt% dissolved H2O and a dense population of hematite crystals (87 ± 2 × 105 mm−3) Pressure was decreased from the saturation value to a final value ranging from 99 to 20 MPa, at constant temperature (800°C); the rate of decompression was either 1,000 or 278 kPa/s In all experiments, we observed a single event of heterogeneous bubble nucleation beginning at a pressure PN equal to 63 ± 3 MPa in the 1,000 kPa/s series, and to 69 ± 1 MPa in the 278 kPa/s series Below PN, the degree of water supersaturation in the liquid rapidly decreased to a few 01 wt%, the nucleation rate dropped, and the bubble number density (BND) stabilized to a value strongly sensitive to decompression rate: 80 mm−3 at 278 kPa/s vs 5,900 mm−3 at 1,000 kPa/s This behaviour is like the behavior formerly described in the case of homogeneous bubble nucleation in the rhyolite-H2O system and in numerical simulations of vesiculation in ascending magmas Similar degrees of water supersaturation were measured at 278 and 1,000 kPa/s, implying that a faster decompression rate does not result in a larger departure from equilibrium Our experimental results imply that BNDs in acid to intermediate magmas ascending in volcanic conduits will depend on both the decompression rate \( \left| {\left {{\text{d}}P/{\text{d}}t} \right|} \right \) and the number density of phenocrysts, especially the number density of magnetite microphenocrysts (1–100 mm−3), which is the only mineral species able to reduce significantly the degree of water supersaturation required for bubble nucleation Very low BNDs (≈1 mm−3) are predicted in the case of effusive eruptions (\( \left| {\left {{\text{d}}P/{\text{d}}t} \right|} \right \) ≈ 01 kPa/s) High BNDs (up to 107 mm−3) and bimodal bubble size distributions are expected in the case of explosive eruptions: (1) a relatively small number density of bubbles (1–100 mm−3) will first nucleate in the lower part of the conduit (\( \left| {\left {{\text{d}}P/{\text{d}}t} \right|} \right \) ≈ 10 kPa/s), either at high pressure on magnetite or at lower pressure on quartz and feldspar (or by homogeneous nucleation in the liquid) and (2) then, extreme decompression rates near the fragmentation level (\( \left| {\left {{\text{d}}P/{\text{d}}t} \right|} \right \) ≈ 103 kPa/s) will trigger a major nucleation event leading to the multitude of small bubbles, typically a few micrometers to a few tens of micrometers in diameter, which characterizes most silicic pumices

Light nuclei quasiparticle energy shift in hot and dense nuclear matter

Abstract: Nuclei in dense matter are influenced by the medium. In the cluster mean field approximation, an effective Schr\"odinger equation for the $A$-particle cluster is obtained accounting for the effects of the correlated medium such as self-energy, Pauli blocking and Bose enhancement. Similar to the single-baryon states (free neutrons and protons), the light elements ($2 \le A \le 4$, internal quantum state $ u$) are treated as quasiparticles with energies $E_{A, u}(\vec P; T, n_n,n_p)$. These energies depend on the center of mass momentum $\vec P$, as well as temperature $T$ and the total densities $n_n,n_p$ of neutrons and protons, respectively. No $\beta$ equilibrium is considered so that $n_n, n_p$ (or the corresponding chemical potentials $\mu_n, \mu_p$) are fixed independently. For the single nucleon quasiparticle energy shift, different approximate expressions such as Skyrme or relativistic mean field approaches are well known. Treating the $A$-particle problem in appropriate approximations, results for the cluster quasiparticle shifts are given. Properties of dense nuclear matter at moderate temperatures in the subsaturation density region considered here are influenced by the composition. This in turn is determined by the cluster quasiparticle energies, in particular the formation of clusters at low densities when the temperature decreases, and their dissolution due to Pauli blocking as the density increases. Our finite-temperature Green function approach covers different limiting cases: The low-density region where the model of nuclear statistical equilibrium and virial expansions can be applied, and the saturation density region where a mean field approach is possible.

Lifetime of the A(v ' = 0) state and Franck-Condon factor of the A-X(0-0) transition of CaF measured by the saturation of laser-induced fluorescence

Abstract: We describe a method for determining the radiative decay properties of a molecule by studying the saturation of laser-induced fluorescence and the associated power broadening of spectral lines. The fluorescence saturates because the molecules decay to states that are not resonant with the laser. The amplitudes and widths of two hyperfine components of a spectral line are measured over a range of laser intensities and the results compared to a model of the laser-molecule interaction. Using this method we measure the lifetime of the $A({v}^{\ensuremath{'}}=0)$ state of CaF to be $\ensuremath{\tau}=19.2\ifmmode\pm\else\textpm\fi{}0.7\phantom{\rule{0.3em}{0ex}}\mathrm{ns}$, and the Franck-Condon factor for the transition to the $X(v=0)$ state to be $Z={0.987}_{\ensuremath{-}0.019}^{+0.013}$. In addition, our analysis provides a measure of the hyperfine interval in the lowest-lying state of $A({v}^{\ensuremath{'}}=0)$, ${\ensuremath{\Delta}}_{e}=4.8\ifmmode\pm\else\textpm\fi{}1.1\phantom{\rule{0.3em}{0ex}}\mathrm{MHz}$.

New complex G -matrix interactions derived from two- and three-body forces and application to proton-nucleus elastic scattering

Abstract: A new type of complex $G$-matrix interactions including the effect of three-body nucleon-nucleon ($\mathit{NN}$) force is proposed and applied to the folding-model calculation of proton-nucleus elastic scattering at ${E}_{p}=65~200$ MeV for ${}^{12}\mathrm{C},{}^{40}\mathrm{Ca},{}^{90}\mathrm{Zr}$, and $^{208}\mathrm{Pb}$ target nuclei. All the measured cross sections and analyzing powers are well reproduced by the folding potentials with the new complex $G$-matrix interaction when the effect of three-body force (TBF) is included so as to give the reasonable saturation property. The inclusion of TBF largely reduces the strength of real-central component of folding potential at middle and short distances. The TBF effect is clearly observed in drastic improvements of analyzing powers at forward angles, which is, however, due to the TBF effect on the real-central potentials, not to the direct effects on the spin-orbit potentials. The calculated folding potential is shown to be very sensitive to the difference of neutron-density profile of the target nucleus.

Density-induced suppression of the α-particle condensate in nuclear matter and the structure of α-cluster states in nuclei

Abstract: At low densities, with decreasing temperatures, in symmetric nuclear matter \ensuremath{\alpha} particles are formed, which eventually give raise to a quantum condensate with four-nucleon \ensuremath{\alpha}-like correlations (quartetting). Starting with a model of \ensuremath{\alpha} matter, where undistorted \ensuremath{\alpha} particles interact via an effective interaction such as the Ali-Bodmer potential, the suppression of the condensate fraction at zero temperature with increasing density is considered. Using a Jastrow-Feenberg approach, it is found that the condensate fraction vanishes near saturation density. Additionally, the modification of the internal state of the \ensuremath{\alpha} particle due to medium effects will further reduce the condensate. In finite systems, an enhancement of the $S$-state wave function of the center-of-mass orbital of \ensuremath{\alpha}-particle motion is considered as the correspondence to the condensate. Wave functions have been constructed for self-conjugate $4n$ nuclei that describe the condensate state but are fully antisymmetrized on the nucleonic level. These condensate-like cluster wave functions have been successfully applied to describe properties of low-density states near the $n\ensuremath{\alpha}$ threshold. Comparison with orthogonality condition model calculations in $^{12}\mathrm{C}$ and $^{16}\mathrm{O}$ shows strong enhancement of the occupation of the $S$-state center-of-mass orbital of the \ensuremath{\alpha} particles. This enhancement is decreasing if the baryon density increases, similar to the density-induced suppression of the condensate fraction in \ensuremath{\alpha} matter. The ground states of $^{12}\mathrm{C}$ and $^{16}\mathrm{O}$ show no enhancement at all, thus a quartetting condensate cannot be formed at saturation densities.

Magnetism and the Verwey transition in Fe 3 O 4 under pressure

Abstract: We have used high precision neutron diffraction and ab initio calculations to investigate the behavior of the magnetism of spinel magnetite $({\mathrm{Fe}}_{3}{\mathrm{O}}_{4})$ under pressure in the $0--10\phantom{\rule{0.3em}{0ex}}\mathrm{GPa}$ range and at temperatures of $130--300\phantom{\rule{0.3em}{0ex}}\mathrm{K}$. We find a significant but continuous decrease of the magnetic moments at both the $A$ and $B$ sites to at least $10\phantom{\rule{0.3em}{0ex}}\mathrm{GPa}$, as well as an absence of any detectable pressure dependence of the oxygen atomic parameter. The data indicate a very weak dependence of the saturation moment on pressure and temperature and rule out unambiguously a transition from inverse to normal spinel in the $P∕T$ range investigated. Consequently, charge ordering cannot be precluded as the origin of the Verwey transition under pressure.

Breakdown of electrostatic predictions for the nonlinear dispersion relation of a stimulated Raman scattering driven plasma wave

Abstract: The kinetic nonlinear dispersion relation, and frequency shift {delta}{omega}{sub srs}, of a plasma wave driven by stimulated Raman scattering (SRS) are presented. Our theoretical calculations are fully electromagnetic, and use an adiabatic expression for the electron susceptibility which accounts for the change in phase velocity as the wave grows. When k{lambda}{sub D} {approx}> 0.35 (k being the plasma wave number and {lambda}{sub D} the Debye length), {delta}{omega}{sub srs} is significantly larger than could be inferred by assuming that the wave is freely propagating. Our theory is in excellent agreement with 1-D Eulerian Vlasov-Maxwell simulations when 0.3 {le} k{lambda}{sub D} {le} 0.58, and allows discussion of previously proposed mechanisms for Raman saturation. In particular, we find that no 'loss of resonance' of the plasma wave would limit the Raman growth rate, and that saturation through a phase detuning between the plasma wave and the laser drive is mitigated by wave number shifts.

Epipelic and pelagic primary production in Alaskan Arctic lakes of varying depth

Abstract: We compared on eight dates during the ice-free period physicochemical properties and rates of phytoplankton and epipelic primary production in six arctic lakes dominated by soft bottom substrate. Lakes were classified as shallow ( $$ \overline {\text{z}} $$ < 2.5 m), intermediate in depth (2.5 m < $$ \overline {\text{z}} $$ < 4.5 m), and deep ( $$ \overline {\text{z}} $$ > 4.5 m), with each depth category represented by two lakes. Although shallow lakes circulated freely and intermediate and deep lakes stratified thermally for the entire summer, dissolved oxygen concentrations were always >70% of saturation values. Soluble reactive phosphorus and dissolved inorganic nitrogen (DIN = NO3 −–N + NH4 +–N) were consistently below the detection limit (0.05 μmol l−1) in five lakes. However, one lake shallow lake (GTH 99) periodically showed elevated values of DIN (17 μmol l−1), total-P (0.29 μmol l−1), and total-N (33 μmol l−1), suggesting wind-generated sediment resuspension. Due to increased nutrient availability or entrainment of microphytobenthos, GTH 99 showed the highest average volume-based values of phytoplankton chlorophyll a (chl a) and primary production, which for the six lakes ranged from 1.0 to 2.9 μg l−1 and 0.7–3.8 μmol C l−1 day−1. Overall, however, increased $$ \overline {\text{z}} $$ resulted in increased area-based values of phytoplankton chl a and primary production, with mean values for the three lake classes ranging from 3.6 to 6.1 mg chl a m−2 and 3.2–5.8 mmol C m−2 day−1. Average values of epipelic chl a ranged from 131 to 549 mg m−2 for the three depth classes, but levels were not significantly different due to high spatial variability. However, average epipelic primary production was significantly higher in shallow lakes (12.2 mmol C m−2 day−1) than in intermediate and deep lakes (3.4 and 2.4 mmol C m−2 day−1). Total primary production (6.7–15.4 mmol C m−2 day−1) and percent contribution of the epipelon (31–66%) were inversely related to mean depth, such that values for both variables were significantly higher in shallow lakes than in intermediate or deep lakes.

Multi-K nuclei and kaon condensation

Abstract: We extend previous relativistic mean-field (RMF) calculations of multi-$\overline{K}$ nuclei, using vector boson fields with SU(3) PPV coupling constants and scalar boson fields constrained phenomenologically. For a given core nucleus, the resulting $\overline{K}$ separation energy ${B}_{\overline{K}}$, as well as the associated nuclear and $\overline{K}$-meson densities, saturate with the number \ensuremath{\kappa} of $\overline{K}$ mesons for $\ensuremath{\kappa}g{\ensuremath{\kappa}}_{\mathrm{sat}}~10$. Saturation appears robust against a wide range of variations, including the RMF nuclear model used and the type of boson fields mediating the strong interactions. Because ${B}_{\overline{K}}$ generally does not exceed 200 MeV, it is argued that multi-$\overline{K}$ nuclei do not compete with multihyperonic nuclei in providing the ground state of strange hadronic configurations and that kaon condensation is unlikely to occur in strong-interaction self-bound strange hadronic matter. Last, we explore possibly self-bound strange systems made of neutrons and ${\overline{K}}^{0}$ mesons, or protons and ${K}^{\ensuremath{-}}$ mesons, and study their properties.

High transverse momentum Hadron spectra at VSnn=17.3 GeV, in Pb+Pb and p+p collisions

Abstract: Transverse momentum spectra up to 4.5 GeV/c around midrapidity of {pi}{sup {+-}},p,p, and K{sup {+-}} in Pb+Pb reactions were measured at {radical}(s{sub NN})=17.3 GeV by the CERN-NA49 experiment. The nuclear modification factors R{sub AA} for {pi}{sup {+-}} and R{sub CP} for {pi}{sup {+-}},p,p,K{sup {+-}} were extracted and compared with results obtained at the BNL Relativistic Heavy Ion Collider (RHIC) at {radical}(s{sub NN})=200 GeV. The modification factor R{sub AA} shows a rapid increase with transverse momentum in the covered region. This indicates that the Cronin effect is the dominating effect in our energy range. The modification factor R{sub CP}, in which the contribution of the Cronin effect is reduced, shows a saturation well below unity in the {pi}{sup {+-}} channel. The extracted R{sub CP} values follow the 200 GeV RHIC results closely in the available transverse momentum range, except for {pi}{sup {+-}} above 2.5 GeV/c transverse momentum. There the measured suppression is smaller than that observed at RHIC.

Saturation Numbers of Books

Abstract: A book $B_p$ is a union of $p$ triangles sharing one edge. This idea was extended to a generalized book $B_{b,p}$, which is the union of $p$ copies of a $K_{b+1}$ sharing a common $K_b$. A graph $G$ is called an $H$-saturated graph if $G$ does not contain $H$ as a subgraph, but $G\cup \{xy\}$ contains a copy of $H$, for any two nonadjacent vertices $x$ and $y$. The saturation number of $H$ , denoted by $sat(H,n)$, is the minimum number of edges in $G$ for all $H$-saturated graphs $G$ of order $n$. We show that $$ sat(B_p, n) = {1\over2} \big( (p+1)(n-1) - \big\lceil {p\over2}\big\rceil \big\lfloor {p\over2} \big\rfloor + \theta(n,p)\big), $$ where $\theta(n, p) = \begin{cases} 1& \text{ if } p\equiv n -p/2 \equiv 0 \bmod 2 \\ 0& \text{ otherwise}\end{cases}$, provided $n \ge p^3 + p$. Moreover, we show that $$\eqalign{ sat(B_{b,p}, n) = \ & {1\over2} \big( (p+2b-3)(n-b+1) - \big\lceil {p\over2}\big\rceil \big\lfloor {p\over2} \big\rfloor\cr &+ \theta(n,p, b)+(b-1)(b-2) \big),\cr} $$ where $\theta(n, p, b) = \begin{cases} 1& \text{ if } p \equiv n -p/2 -b \equiv 0 \bmod 2 \\ 0 & \text{ otherwise} \end{cases}$, provided $n \ge 4(p+2b)^{b}$.

Multi-$\bar{K}$ nuclei and kaon condensation

Abstract: We extend previous relativistic mean-field (RMF) calculations of multi-$\bar K$ nuclei, using vector boson fields with SU(3) PPV coupling constants and scalar boson fields constrained phenomenologically. For a given core nucleus, the resulting $\bar K$ separation energy $B_{\bar K}$, as well as the associated nuclear and $\bar K$-meson densities, saturate with the number $\kappa$ of $\bar K$ mesons for $\kappa > \kappa_{\rm sat} \sim 10$. Saturation appears robust against a wide range of variations, including the RMF nuclear model used and the type of boson fields mediating the strong interactions. Because $B_{\bar K}$ generally does not exceed 200 MeV, it is argued that multi-$\bar K$ nuclei do not compete with multihyperonic nuclei in providing the ground state of strange hadronic configurations and that kaon condensation is unlikely to occur in strong-interaction self-bound strange hadronic matter. Last, we explore possibly self-bound strange systems made of neutrons and ${\bar K}^0$ mesons, or protons and $K^-$ mesons, and study their properties.

Quantum delocalization of molecular hydrogen in alkali-graphite intercalates.

Abstract: The adsorption of molecular hydrogen (${\mathrm{H}}_{2}$) in the graphite intercalation compound ${\mathrm{KC}}_{24}$ is studied both experimentally and theoretically. High-resolution inelastic neutron data show spectral features consistent with a strong pinning of ${\mathrm{H}}_{2}$ along a single axis. First-principles calculations provide novel insight into the nature of ${\mathrm{H}}_{2}$ binding in intercalates but fail to account for the symmetry of the ${\mathrm{H}}_{2}$ orientational potential deduced from experiment. The above discrepancy disappears once the ${\mathrm{H}}_{2}$ center of mass is allowed to delocalize in the quantum-mechanical sense across three vicinal adsorption sites, naturally leading to the well-known saturation coverage of $\ensuremath{\sim}2{\mathrm{H}}_{2}$ per metal atom in this material. Our results demonstrate that ${\mathrm{H}}_{2}$ storage in metal-doped carbon substrates can be severely affected by hitherto unexplored quantum-mechanical effects.

Modeling of the microbunching instability

Abstract: We show that, through careful control of noise sources, it is possible to determine the microbunching gain curve for the FERMI@ELETTRA linac using the particle tracking code elegant. In addition to using a sufficiently large number of particles ($60\ifmmode\times\else\texttimes\fi{}{10}^{6}$), use of a low-pass filter is very helpful in controlling noise and providing convenient intrabin interpolation. Gains of up to 1500 are seen for modulation wavelengths down to $25\text{ }\text{ }\ensuremath{\mu}\mathrm{m}$. Because of the high gain, very small initial modulations are needed to avoid saturation, which further motivates the use of a large number of particles. We also show, for the first time, how the density modulation evolves in detail inside the dipoles of a multichicane system.

Two-electron photodetachment of negative ions in a strong laser field.

Abstract: We study the photodetachment of ${\mathrm{H}}^{\ensuremath{-}}$, ${\mathrm{F}}^{\ensuremath{-}}$, and ${\mathrm{Br}}^{\ensuremath{-}}$ in a short laser pulse of 800 nm wavelength and $6\ifmmode\times\else\texttimes\fi{}{10}^{14}\text{ }\text{ }\mathrm{W}/{\mathrm{cm}}^{2}$ peak intensity. Photoelectron spectra, recorded with the use of an imaging technique, reveal a substantial contribution from the sequential process of double detachment of halogen negative ions. The saturation effect is shown to play a crucial role in this process. The role of the alignment of atoms produced by photodetachment is discussed.

Folding 3-noncrossing RNA pseudoknot structures

Abstract: In this paper we present a selfcontained analysis and description of the novel {\it ab initio} folding algorithm {\sf cross}, which generates the minimum free energy (mfe), 3-noncrossing, $\sigma$-canonical RNA structure. Here an RNA structure is 3-noncrossing if it does not contain more than three mutually crossing arcs and $\sigma$-canonical, if each of its stacks has size greater or equal than $\sigma$. Our notion of mfe-structure is based on a specific concept of pseudoknots and respective loop-based energy parameters. The algorithm decomposes into three parts: the first is the inductive construction of motifs and shadows, the second is the generation of the skeleta-trees rooted in irreducible shadows and the third is the saturation of skeleta via context dependent dynamic programming routines.

Coulomb drag at zero temperature.

Abstract: We show that the Coulomb drag effect exhibits saturation at small temperatures, when calculated to the third order in the interlayer interactions. The zero-temperature transresistance is of the order $h/({e}^{2}{g}^{3})$, where $g$ is the dimensionless sheet conductance. The effect is therefore the strongest in low mobility samples. This behavior should be contrasted with the conventional (second order) prediction that the transresistance scales as a certain power of temperature and is (almost) mobility independent. The result demonstrates that the zero-temperature drag is not an unambiguous signature of a strongly coupled state in double-layer systems.

Ultrafast electron dynamics and cubic optical nonlinearity of free standing thin film of double walled carbon nanotubes

Abstract: Ultrafast degenerate pump-probe experiments performed on a free standing film of double walled carbon nanotubes near the first metallic transition energy of outer tube show ultrafast ($97 fs$) photobleaching followed by a photo-induced absorption with a slow relaxation of $1.8 ps$. Femtosecond closed and open aperture z-scan experiments carried out at the same excitation energy show saturation absorption and negative cubic nonlinearity. From these measurements, real and imaginary part of the third order nonlinear susceptibility are estimated to be Re($\chi^{(3)}) \sim -2.2 \times 10 ^{-9} esu$ and Im($\chi^{(3)}) \sim 1.1 \times 10 ^{-11} esu$.

Effect of static and dynamic disorder on electronic transport in R Co 2 compounds: Ho ( Al x Co 1 − x ) 2 alloys

Abstract: We present experimental results on thermoelectric power $(S)$ and electrical resistivity $(\ensuremath{\rho})$ of pseudobinary alloys $\text{Ho}{({\text{Al}}_{x}{\text{Co}}_{1\ensuremath{-}x})}_{2}$ $(0\ensuremath{\le}x\ensuremath{\le}0.1)$, in the temperature range 4.2 to 300 K. The work focuses on the effects of static (induced by alloying) and dynamic (induced by temperature) disorder on the magnetic state and electronic transport in a metallic system with itinerant metamagnetic instability. Spatial fluctuations of the local magnetic susceptibility in the alloys lead to the development of a partially-ordered magnetic ground state of the itinerant $3d$ electron system. This results in a strong increase of the residual resistivity and a suppression of the temperature-dependent resistivity. Thermopower exhibits a complex temperature variation in both the magnetically ordered and in the paramagnetic state. This complex temperature variation is attributed to the electronic density-of-states features in vicinity of Fermi energy and to the interplay of magnetic and impurity scattering. Our results indicate that the magnetic enhancement of the $\text{Co}\text{ }3d$ band in $R{\text{Co}}_{2}$-based alloys upon a substitution of Co by nonmagnetic elements is mainly related to a progressive localization of the $\mathrm{Co}\text{ }3d$ electrons caused by disorder. We show that the magnitude of the resistivity jump at the Curie temperature for $R{\text{Co}}_{2}$ compounds exhibiting a first-order phase transition is a nonmonotonic function of the Curie temperature due to a saturation of the $3d$-band spin-fluctuation magnitude at high temperatures.

Coulomb drag at zero temperature

Abstract: We show that the Coulomb drag effect exhibits saturation at small temperatures, when calculated to the third order in the interlayer interactions. The zero-temperature transresistance is of the order $h/({e}^{2}{g}^{3})$, where $g$ is the dimensionless sheet conductance. The effect is therefore the strongest in low mobility samples. This behavior should be contrasted with the conventional (second order) prediction that the transresistance scales as a certain power of temperature and is (almost) mobility independent. The result demonstrates that the zero-temperature drag is not an unambiguous signature of a strongly coupled state in double-layer systems.

Ergodic conditions and spectral properties for A-contractions

Abstract: In this paper the canonical representation of an \(A\)-contraction \(T\) on a Hilbert space \(\mathcal{H}\) is used to obtain some conditions concerning the concept of \(A\)-ergodicity studied in [L. Suciu, Orthogonal decompositions induced by generalized contractions, Acta Sci. Math. (Szeged) 70 (2004), 751–765; L. Suciu, On the ergodic \(A\)-contractions, Analele Universitaţii de Vest din Timisoara, Ser. Mat.-Inf. 2 (2004), 115–136; L. Suciu, Ergodic properties for regular \(A\)-contractions, Integral Equations and Operator Theory 56 (2006) 2, 285–299; L. Suciu, Ergodic properties and saturation for \(A\)-contractions, Operator Theory: Advances and Applications; Proceeding of 20th Conference on Operator Theory, Timisoara 2004, Theta 2006, 225–242]. The regular case and the case of \(\mathcal{R}(A)\) closed are considered, and specifically, the \(TT^{*}\)-contractions are studied. Some spectral properties are also given for certain particular class of \(A\)-isometries.

Oscillator strength measurements of the 3 p 5 ( P 1 ∕ 2 2 ) n d ′ [ 3 ∕ 2 ] 2 and [ 5 ∕ 2 ] 2 , 3 autoionizing resonances in argon

Abstract: We present measurements of oscillator strengths of the $3{p}^{5}n{d}^{\ensuremath{'}}$ $J=2,3$ autoionizing Rydberg states in argon using two-step laser excitation in conjunction with an optogalvanic detection in a dc discharge cell. The $3{p}^{5}4{p}^{\ensuremath{'}}{[3∕2]}_{1,2}$ and ${[1∕2]}_{1}$ intermediate levels were populated via the $3{p}^{5}4s{[3∕2]}_{2}$ metastable state, collisionally populated in the discharge. The photoionization cross section from the $3{p}^{5}4{p}^{\ensuremath{'}}{[3∕2]}_{1,2}$ and ${[1∕2]}_{1}$ intermediate levels has been measured at the $3{p}^{5}\phantom{\rule{0.2em}{0ex}}^{2}P_{1∕2}$ ionization threshold as $34\ifmmode\pm\else\textpm\fi{}5$, $31\ifmmode\pm\else\textpm\fi{}5$, and $28\ifmmode\pm\else\textpm\fi{}4\phantom{\rule{0.3em}{0ex}}\mathrm{Mb}$, respectively, using the saturation technique. The measured absolute cross section values at the $3{p}^{5}\phantom{\rule{0.2em}{0ex}}^{2}P_{1∕2}$ threshold have been used to determine the $f$ values for the $4{p}^{\ensuremath{'}}{[3∕2]}_{1}\ensuremath{\rightarrow}n{d}^{\ensuremath{'}}{[5∕2]}_{2}$, $4{p}^{\ensuremath{'}}{[3∕2]}_{2}\ensuremath{\rightarrow}n{d}^{\ensuremath{'}}{[5∕2]}_{3}$, and $4{p}^{\ensuremath{'}}{[1∕2]}_{1}\ensuremath{\rightarrow}n{d}^{\ensuremath{'}}{[3∕2]}_{2}$ transitions. The extracted $f$ values are corrected by incorporating the contribution of the Fano line shape parameters for the autoionizing resonances.

Forward Physics at the LHC; Elastic Scattering

Abstract: The following effects in the nearly forward ("soft") region of the LHC are proposed to be investigated: 1) At small |t| the fine structure of the cone (Pomeron) shouldbe scrutinized: a) a break of the cone near $t\approx - 0.1 ~ GeV$^2, due to the two-pion threshold, and required by t-channel unitarity, is expected, and b) possible small-period oscillations between $t=0$ and the dip region. 2) In measuring the elastic $pp$ scattering and total $pp$ cross section at the LHC, the experimentalists are urged to treat the total cross section $\sigma_t,$ the ratio $\rho$, the forward slope $B$ and the luminosity ${\cal L}$ as free arameters, and to publish model-independent results on ${dN/{dt}}.$ 3) Of extreme interest are the details of the expected diffraction minimum in the differential cross section. Its position, expected in the interval $0.4<-t<1$ GeV$^2$ at the level of about $10^{-2} {\rm mb} \cdot$ GeV$^{-2}÷10^{-1} {\rm mb}\cdot$ GeV$^{-2}$, cannot be predicted unambiguously, and its depth, i.e. the ratio of $d\sigma/dt$ at the minimum to that at the subsequent maximum (about $-t=5 $GeV$^2$, which is about 5 is of great importance. 4) The expected slow-down with increasing $|t|$ of the shrinkage of the second cone (beyond the dip-bump), together with the transition from an exponential to a power decrease in $-t$, will be indicative of the transition from "soft" to "hard" physics. Explicit models are proposed to help in quantifying this transition. 5) In a number of papers a limiting behavior, or saturation of the black disc limit (BDL) was predicted. This controversial phenomenon shows that the BDL may not be the ultimate limit.

Saturation and Confinement: Analyticity, Unitarity and AdS/CFT Correspondence

Abstract: In $1/N_c$ expansion, analyticity and crossing lead to crossing even and odd ($C=\pm 1$) vacuum exchanges at high-energy, the {\em Pomeron} and the {\em Odderon}. We discuss how, using {\em String/Gauge duality}, these can be identified with a reggeized {\em Graviton} and the anti-symmetric {\em Kalb-Ramond fields} in $AdS$ background. With confinement, these Regge singularities interpolate with glueball states. We also discuss unitarization based on eikonal sum in $AdS$.

An alternative construction in symbolic reachability analysis of second order pushdown systems

Abstract: Recently, it has been shown that for any higher order pushdown system $\mathcal{H}$ and for any regular set $\mathcal{C}$ of configurations, the set $pre^{\ast}_\mathcal{H}(\mathcal{C})$, is regular. In this paper, we give an alternative proof of this result for second order automata. Our construction of automaton for recognizing $pre^{\ast}_\mathcal{H}(\mathcal{C})$ is explicit. The termination of saturation procedure used is obvious. It gives EXPTIME bound on size of the automaton recognizing $pre^{\ast}_\mathcal{H}(\mathcal{C})$ if there is no alternation present in $\mathcal{H}$ and in the automaton recognizing $\mathcal{C}$.

Saturation of nuclear matter in effective field theory

Abstract: The two- and three-nucleon interaction derived in chiral effective field theory at next-to-next-to-leading order is used to obtain the binding energy of nuclear matter. Saturation is found at a binding energy per particle E/A = -16.2 \pm 0.3 MeV and a Fermi momentum k_F = 1.30 \pm 0.03 fm^{-1}, where the uncertainty is due to the cut-off dependence of the two-nucleon interaction. The sensitivity of these values to the three-nucleon force is also studied.

The presence of a thermally reversing window in Al–Te–Si glasses revealed by alternating differential scanning calorimetry and electrical switching studies

Abstract: Alternating differential scanning calorimetric (ADSC) studies and electrical switching experiments have been undertaken on $Al_{15}Te_{85-x}Si_x$ (2 \leq x \leq 12) system of glasses. These glasses are found to exhibit two crystallization reactions $(T_{c1} and T_{c2})$, for compositions with x < 8. Above x = 8, a single-stage crystallization is seen. Further, a trough is seen in the composition dependence of nonreversing enthalpy (DHNR), based on which it is proposed that there is a thermally reversing window in $Al_{15} Te_{85-x}Si_x$ glasses, in the composition range 4 \leq x \leq 8. Electrical switching studies indicate that $Al_{15} Te_{85-x}Si_x$ glasses exhibit a threshold type electrical switching at ON state currents less than 2 mA. Further, the switching voltages are found to increase with the increase in silicon content. It is interesting to note that the start (x = 4) and the end (x = 8) of the thermally reversing window are exemplified by a kink and a saturation in the composition dependence of switching voltages, respectively.