Baryon Number Flow in High-Energy Collisions

It is not obvious which partons in the proton carry its baryon number (BN). We present arguments that BN is associated with a specific topology of gluonic fields, rather than with the valence quarks. The BN distribution is easily confused with the difference between the quark and antiquark distributions. We argue, however, that they have quite different x-dependences. The distribution of BN asymmetry distribution is nearly constant at small x while q(x)-\bar q(x) \propto \sqrt{x}. This constancy of BN produces energy independence of the \bar pp annihilation cross section at high energies. Recent measurement of the baryon asymmetry at small x at HERA confirms this expectation. The BN asymmetry at mid-rapidities in heavy ion collisions is substantially enhanced by multiple interactions, as has been observed in recent experiments at the SPS. The same gluonic mechanism of BN stopping increases the production rate for cascade hyperons in a good accord with data. We expect nearly the same as at SPS amount of BN stopped in higher energy collisions at RHIC and LHC, which is, however, spread ove larger rapidity intervals.Comment: The estimated baryon stopping at RHIC is corrected in the Summar

Time dependent decomposition of ammonia borane for the controlled production of 2D hexagonal boron nitride.

Ammonia borane (AB) is among the most promising precursors for the large-scale synthesis of hexagonal boron nitride (h-BN) by chemical vapour deposition (CVD). Its non-toxic and non-flammable properties make AB particularly attractive for industry. AB decomposition under CVD conditions, however, is complex and hence has hindered tailored h-BN production and its exploitation. To overcome this challenge, we report in-depth decomposition studies of AB under industrially safe growth conditions. In situ mass spectrometry revealed a time and temperature-dependent release of a plethora of NxBy-containing species and, as a result, significant changes of the N:B ratio during h-BN synthesis. Such fluctuations strongly influence the formation and morphology of 2D h-BN. By means of in situ gas monitoring and regulating the precursor temperature over time we achieve uniform release of volatile chemical species over many hours for the first time, paving the way towards the controlled, industrially viable production of h-BN

Herschel/HIFI Spectral Mapping of C+^+, CH+^+, and CH in Orion BN/KL: The Prevailing Role of Ultraviolet Irradiation in CH+^+ Formation

The CH$^+$ ion is a key species in the initial steps of interstellar carbon chemistry. Its formation in diverse environments where it is observed is not well understood, however, because the main production pathway is so endothermic (4280 K) that it is unlikely to proceed at the typical temperatures of molecular clouds. We investigation CH$^+$ formation with the first velocity-resolved spectral mapping of the CH$^+$ $J=1-0, 2-1$ rotational transitions, three sets of CH $\Lambda$-doubled triplet lines, $^{12}$C$^+$ and $^{13}$C$^+$, and CH$_3$OH 835~GHz E-symmetry Q branch transitions, obtained with Herschel/HIFI over $\approx$12 arcmin$^2$ centered on the Orion BN/KL source. We present the spatial morphologies and kinematics, cloud boundary conditions, excitation temperatures, column densities, and $^{12}$C$^+$ optical depths. Emission from C$^+$, CH$^+$, and CH is indicated to arise in the diluted gas, outside of the explosive, dense BN/KL outflow. Our models show that UV-irradiation provides favorable conditions for steady-state production of CH$^+$ in this environment. Surprisingly, no spatial or kinematic correspondences of these species are found with H$_2$ S(1) emission tracing shocked gas in the outflow. We propose that C$^+$ is being consumed by rapid production of CO to explain the lack of C$^+$ and CH$^+$ in the outflow, and that fluorescence provides the reservoir of H$_2$ excited to higher ro-vibrational and rotational levels. Hence, in star-forming environments containing sources of shocks and strong UV radiation, a description of CH$^+$ formation and excitation conditions is incomplete without including the important --- possibly dominant --- role of UV irradiation.Comment: Accepted for publication in The Astrophysical Journa

Pengaruh Scale terhadap Produktivitas pada Sumur Bn-52, Bn-104, dan Bn-110 di Lapangan “X”

BN-52, BN-104, and BN-110 wells are located on the X field, PT. PERTAMINA FIELD RAMBA ASSET 1, South Sumatra. The three wells are oil-producing wells in field X. Using the Vogel equation, the IPR curve and maximum flow rate of each well are obtained, which are 152.14 BOPD, 57.2 BOPD, and 53.76 BOPD respectively. By using the exponential Decline Curve Analysis calculation method, it can be seen the rate of decline in production, as well as the time of well production to economic limit. The results of the Decline Curve Analysis show that the BN-52 well will still be in production until March 2022, and the BN-110 well can produce until March 2020. In the analysis with the Stiff & Davis Method, carbonate deposits are proven, with each Stability Index value +1.19, +1.60, and +1.35, whereas with the Skillman, Mcdonald & Stiff method there was no scale sulfate, with S values of each well at 57,272 meq / l, 54,416 meq / l, and 55,147 meq / l. The scale causes oil production to decrease, consequently the IPR curve shifts to the left. The decreasing production of the three wells is due to a scale that inhibits the flow rate. Maximum flow rate was obtained by using the Standing correlation in each well of 100.06 BOPD, 54.53 BOPD, and 28.72 BOPD. The decline in oil production caused by scales must be handled appropriately

Regulation of FATTY ACID ELONGATION1 expression in embryonic and vascular tissues of Brassica napus

International audienceThe expression of the FATTY ACID ELONGATION1 genes was characterised to provide insight into the regulation of very long chain fatty acid (VLCFA) biosynthesis in Brassica napus embryos. Each of the two rapeseed homoeologous genes (Bn-FAE1.1 and Bn-FAE1.2) encoding isozymes of 3-keto-acylCoA synthase, a subunit of the cytoplasmic acyl-CoA elongase complex that controls the production of elongated fatty acids, are expressed predominantly in developing seeds. The proximal regions of the Bn-FAE1.1 and Bn-FAE1.2 promoters possess strong sequence identity suggesting that transcriptional control of expression is mediated by this region which contains putative cis-elements characteristic of those found in the promoters of genes expressed in embryo and endosperm. Histochemical staining of rapeseed lines expressing Bn-FAE1.1 promoter:reporter gene fusions revealed a strong expression in the embryo cotyledon and axis throughout the maturation phase. Quantitative analyses revealed the region, −331 to −149, exerts a major control on cotyledon specific expression and the level of expression. A second region, −640 to −475, acts positively to enhance expression levels and extends expression of Bn-FAE1.1 into the axis and hypocotyl but also acts negatively to repress expression in the root meristem. The expression of the Bn-FAE1.1 gene was not restricted to the seed but was also detected in the vascular tissues of germinating seedlings and mature plants in the fascicular cambium tissue present in roots, stem and leaf petiole. We propose that Bn-FAE1.1 expression in vascular tissue may contribute VLCFA for barrier lipid synthesis and reflects the ancestral function of FAE1 encoded 3-keto-acylCoA synthase

Composition of the nuclear periphery from antiproton absorption

Thirteen targets with mass numbers from 58 to 238 were irradiated with the antiproton beam from the Low Energy Antiproton Ring facility at CERN leading to the formation of antiprotonic atoms of these heavy elements. The antiproton capture at the end of an atomic cascade results in the production of more or less excited residual nuclei. The targets were selected with the criterion that both reaction products with one nucleon less than the proton and neutron number of the target be radioactive. The yield of these radioactive products after stopped-antiproton annihilation was determined using gamma-ray spectroscopy techniques. This yield is related to the proton and neutron density in the target nucleus at a radial distance corresponding to the antiproton annihilation site. The experimental data clearly indicate the existence of a neutron-rich nuclear periphery, a "neutron halo", strongly correlated with the target neutron separation energy Bn and observed for targets with Bn < 10 MeV. For two-target nuclei 106Cd and 144Sm, with larger neutron binding energies, a proton-rich nuclear periphery was observed. Most of the experimental data are in reasonable agreement with calculations based on current antiproton-nucleus and pion-nucleus interaction potentials and on nuclear densities deduced with the help of the Hartree-Fock-Bogoliubov approach. This approach was, however, unable to account for the 106Cd and 144Sm results.Comment: Latex (RevTeX,aps style), 13 pages + 12 Postscript figure

Assessment of long-term production traits of three breeds of exotic commercial layers in the derived Savannah zone of Nigeria

This study was carried out to compare production traits of three breeds of exotic commercial layers for a production period of 15 months. The breeds are Isa Brown (IB), Bovan Nera (BN) and Dominant Black (DB) and the traits considered are hen-day egg production, feed efficiency and mortality rate. The general means are 5.24eggs/ bird/week, 0.006/bird/week and 0.16/breed/week for egg production, feed efficiency and mortality rate, respectively. There was highly significant (P&lt;0.01) effect of breed on egg production and feed efficiency but the reverse was the case for mortality rate. On egg production, IB genotype recorded 5.37+0.07 eggs/bird/week while BN breed had 5.41+0.08 eggs/bird/week and the values were similar but superior to DB genotype with 4.94eggs/bird/week. For feed efficiency, IB and BN breeds recorded higher mean values and were similar but superior to DB genotype. The mean values are: IB=0.006+9.05x10-5, BN=0.006+8.53x10-5 and DB=0.005/bird/week. Breed’s effect on mortality rate showed that the three genotypes had similar values, that is, breed has no significant (P&gt;0.05) effect on this trait. There was highly significant (P&lt;0.01) effect of age of birds on egg production. Age 2 (2nd month) recorded the highest mean values while age 14 (14th month) was the lowest. The values respectively, are 6.04+0.16 eggs/bird/week and 4.18+0.16 eggs/bird/week. In addition, there was highly significant (P&lt;0.01) effect of age of birds on feedefficiency regardless of the breed of birds. Age 2 (2nd month) recorded the highest mean values and age 14 (14th month) the lowest. There was also highly significant (P&lt;0.01) effect of age on mortality rate of commercial layers. The long-term production analyses showed that IB and BN genotypes are more productive, feed efficient and could be recommended to farmers as commercially viable breeds of layers

Rapid Changes of International Trade Flows Geography. An Approach Grounded on the Knowledge-Based Economy Concept

After the Second World War international merchandise trade has known an impressive rising trend: from 121 bn. USD in 1948 to 25.172 bn. USD in 2009, which means a rise by 210 times, being therefore the economic sector with the most spectacular development. International trade – considered to be the right indicator of a country’s economy – has become one of the major factors of economic development mainly due to the knowledge-based economy. Except for the economic development (translated into high levels of production and productivity, expressed by high figures of GDP), the effect of knowledge has been registered by exports, by their dynamics and high level of foreign markets penetration. It is therefore relevant that three small countries and provinces (the Netherlands, Hong Kong – province of Peoples Republic of China and Singapore) in terms of territory and population are among the first fifteen global exporters (with a percentage of exports ranging from 2,2% and 4%), in contrast with larger countries in terms of surface and population, which play an insignificant role in international trade. These small countries/provinces represent relevant models of using information technology and modern communication, fundamental elements of a knowledge-based economy. Thus, they are very competitive on the global market (the key factor of success). In this paper we argue that humankind is in a transitory phase from industrial economy to knowledge-based economy (in this sense the oil trade is a very good example, as the most traded merchandise).international trade, international trade flows, competitiveness, knowledgebased economy.

Statistical Thermodynamics of General Minimal Diffusion Processes: Constuction, Invariant Density, Reversibility and Entropy Production

The solution to nonlinear Fokker-Planck equation is constructed in terms of the minimal Markov semigroup generated by the equation. The semigroup is obtained by a purely functional analytical method via Hille-Yosida theorem. The existence of the positive invariant measure with density is established and a weak form of Foguel alternative proven. We show the equivalence among self-adjoint of the elliptic operator, time-reversibility, and zero entropy production rate of the stationary diffusion process. A thermodynamic theory for diffusion processes emerges.Comment: 23 page

In situ epitaxial engineering of graphene and h-BN lateral heterostructure with a tunable morphology comprising h-BN domains

Graphene and hexagonal boron nitride (h-BN), as typical two-dimensional (2D) materials, have long attracted substantial attention due to their unique properties and promise in a wide range of applications. Although they have a rather large difference in their intrinsic bandgaps, they share a very similar atomic lattice; thus, there is great potential in constructing heterostructures by lateral stitching. Herein, we present the in situ growth of graphene and h-BN lateral heterostructures with tunable morphologies that range from a regular hexagon to highly symmetrical star-like structure on the surface of liquid Cu. The chemical vapor deposition (CVD) method is used, where the growth of the h-BN is demonstrated to be highly templated by the graphene. Furthermore, large-area production of lateral G-h-BN heterostructures at the centimeter scale with uniform orientation is realized by precisely tuning the CVD conditions. We found that the growth of h-BN is determined by the initial graphene and symmetrical features are produced that demonstrate heteroepitaxy. Simulations based on the phase field and density functional theories are carried out to elucidate the growth processes of G-h-BN flakes with various morphologies, and they have a striking consistency with experimental observations. The growth of a lateral G-h-BN heterostructure and an understanding of the growth mechanism can accelerate the construction of various heterostructures based on 2D materials