Left-Handed W Bosons at the LHC

The production of W bosons in association with jets is an important background to new physics at the LHC. Events in which the W carries large transverse momentum and decays leptonically lead to large missing energy and are of particular importance. We show that the left-handed nature of the W coupling, combined with valence quark domination at a pp machine, leads to a large left-handed polarization for both W^+ and W^- bosons at large transverse momenta. The polarization fractions are very stable with respect to QCD corrections. The leptonic decay of the W bosons translates the common left-handed polarization into a strong asymmetry in transverse momentum distributions between positrons and electrons, and between neutrinos and anti-neutrinos (missing transverse energy). Such asymmetries may provide an effective experimental handle on separating W + jets from top quark production, which exhibits very little asymmetry due to C invariance, and from various types of new physics.Comment: 32 pages, revtex, 17 figures, 3 tables, v2 minor corrections to ME+PS results, no changes to conclusions, added reference

Effective gravity from a quantum gauge theory in Euclidean space-time

We consider a $SO(d)$ gauge theory in an Euclidean $d$-dimensional space-time, which is known to be renormalizable to all orders in perturbation theory for $2\le{d}\le4$. Then, with the help of a space-time representation of the gauge group, the gauge theory is mapped into a curved space-time with linear connection. Further, in that mapping the gauge field plays the role of the linear connection of the curved space-time and an effective metric tensor arises naturally from the mapping. The obtained action, being quadratic in the Riemann-Christoffel tensor, at a first sight, spoils a gravity interpretation of the model. Thus, we provide a sketch of a mechanism that breaks the $SO(d)$ color invariance and generates the Einstein-Hilbert term, as well as a cosmological constant term, allowing an interpretation of the model as a modified gravity in the Palatini formalism. In that sense, gravity can be visualized as an effective classical theory, originated from a well defined quantum gauge theory. We also show that, in the four dimensional case, two possibilities for particular solutions of the field equations are the de Sitter and Anti de Sitter space-times.Comment: 20 pages; Final version accepted for publication in Class.Quant.Gra

Constitutive expression of selected genes from the pentose phosphate and aromatic pathways increases the shikimic acid yield in high-glucose batch cultures of an Escherichia coli strain lacking PTS and pykF

BACKGROUND: During the last two decades many efforts have been directed towards obtaining efficient microbial processes for the production of shikimic acid (SA); however, feeding high amounts of substrate to increase the titer of this compound has invariably rendered low conversion yields, leaving room for improvement of the producing strains. In this work we report an alternative platform to overproduce SA in a laboratory-evolved Escherichia coli strain, based on plasmid-driven constitutive expression of six genes selected from the pentose phosphate and aromatic amino acid pathways, artificially arranged as an operon. Production strains also carried inactivated genes coding for phosphotransferase system components (ptsHIcrr), shikimate kinases I and II (aroK and aroL), pyruvate kinase I (pykF) and the lactose operon repressor (lacI). RESULTS: The strong and constitutive expression of the constructed operon permitted SA production from the beginning of the cultures, as evidenced in 1 L batch-mode fermentors starting with high concentrations of glucose and yeast extract. Inactivation of the pykF gene improved SA production under the evaluated conditions by increasing the titer, yield and productivity of this metabolite compared to the isogenic pykF(+) strain. The best producing strain accumulated up to 43 g/L of SA in 30 h and relatively low concentrations of acetate and aromatic byproducts were detected, with SA accounting for 80% of the produced aromatic compounds. These results were consistent with high expression levels of the glycolytic pathway and synthetic operon genes from the beginning of fermentations, as revealed by transcriptomic analysis. Despite the consumption of 100 g/L of glucose, the yields on glucose of SA and of total aromatic compounds were about 50% and 60% of the theoretical maximum, respectively. The obtained yields and specific production and consumption rates proved to be constant with three different substrate concentrations. CONCLUSIONS: The developed production system allowed continuous SA accumulation until glucose exhaustion and eliminated the requirement for culture inducers. The obtained SA titers and yields represent the highest reported values for a high-substrate batch process, postulating the strategy described in this report as an interesting alternative to the traditionally employed fed-batch processes for SA production

Stability of stationary solutions of the Schrodinger-Langevin equation

The stability properties of a class of dissipative quantum mechanical systems are investigated. The nonlinear stability and asymptotic stability of stationary states (with zero and nonzero dissipation respectively) is investigated by Liapunov's direct method. The results are demonstrated by numerical calculations on the example of the damped harmonic oscillator.Comment: revised, 12 pages, 7 figure

New insights into Escherichia coli metabolism: carbon scavenging, acetate metabolism and carbon recycling responses during growth on glycerol

<p>Abstract</p> <p>Background</p> <p>Glycerol has enhanced its biotechnological importance since it is a byproduct of biodiesel synthesis. A study of <it>Escherichia coli</it> physiology during growth on glycerol was performed combining transcriptional-proteomic analysis as well as kinetic and stoichiometric evaluations in the strain JM101 and certain derivatives with important inactivated genes.</p> <p>Results</p> <p>Transcriptional and proteomic analysis of metabolic central genes of strain JM101 growing on glycerol, revealed important changes not only in the synthesis of MglB, LamB and MalE proteins, but also in the overexpression of carbon scavenging genes: <it>lamB</it>, <it>malE</it>, <it>mglB</it>, <it>mglC</it>, <it>galP</it> and <it>glk</it> and some members of the RpoS regulon (<it>pfkA</it>, <it>pfkB</it>, <it>fbaA</it>, <it>fbaB</it>, <it>pgi, poxB</it>, <it>acs</it>, <it>actP</it> and <it>acnA</it>). Inactivation of <it>rpoS</it> had an important effect on stoichiometric parameters and growth adaptation on glycerol. The observed overexpression of <it>poxB</it>, <it>pta</it>, <it>acs</it> genes, glyoxylate shunt genes (<it>aceA, aceB</it>, <it>glcB</it> and <it>glcC</it>) and <it>actP</it>, suggested a possible carbon flux deviation into the PoxB, Acs and glyoxylate shunt. In this scenario acetate synthesized from pyruvate with PoxB was apparently reutilized via Acs and the glyoxylate shunt enzymes. In agreement, no acetate was detected when growing on glycerol, this strain was also capable of glycerol and acetate coutilization when growing in mineral media and derivatives carrying inactivated <it>poxB</it> or <it>pckA</it> genes, accumulated acetate. Tryptophanase A (TnaA) was synthesized at high levels and indole was produced by this enzyme, in strain JM101 growing on glycerol. Additionally, in the isogenic derivative with the inactivated <it>tnaA</it> gene, no indole was detected and acetate and lactate were accumulated. A high efficiency aromatic compounds production capability was detected in JM101 carrying pJLB<it>aroG</it>^<it>fbr</it><it>tktA</it>, when growing on glycerol, as compared to glucose.</p> <p>Conclusions</p> <p>The overexpression of several carbon scavenging, acetate metabolism genes and the absence of acetate accumulation occurred in JM101 cultures growing on glycerol. To explain these results it is proposed that in addition to the glycolytic metabolism, a gluconeogenic carbon recycling process that involves acetate is occurring simultaneously in this strain when growing on glycerol. Carbon flux from glycerol can be efficiently redirected in JM101 strain into the aromatic pathway using appropriate tools.</p

Evaluar el programa microempresarial desarrollo socio económico aplicado por carbones del caribe en el municipio de la Jagua de Ibiríco (cesar)

Con el presente trabajo buscamos evaluar el programa microempresarial de desarrollo socioeconómico aplicado por la empresa Carbones del Caribe en el municipio de la Jagua de Ibirico (Cesar) con el fin de identificar los problemas que limiten sus acciones. Dado lo anterior los gobiernos de muchos países desarrollados o no, han tomado conciencia de la gran importancia de la pequeña empresa y han dispuesto recursos para estimular y apoyar al nuevo empresario; creando organismos, apropiando fondos y emitiendo disposiciones especiales que faciliten el despegue de las nacientes empresas, en algunos casos con el apoyo del sector privado, como el programa socioeconómico promovido por Carbones del Caribe en el municipio de la Jagua de Ibirico. El perfil de esas nuevas legiones de empresarios no sigue un patrón determinado; se encuentran entre ellos tanto mujeres como hombres, jóvenes llenos de vitalidad y adultos cargados

A direct-to-drive neural data acquisition system

Driven by the increasing channel count of neural probes, there is much effort being directed to creating increasingly scalable electrophysiology data acquisition (DAQ) systems. However, all such systems still rely on personal computers for data storage, and thus are limited by the bandwidth and cost of the computers, especially as the scale of recording increases. Here we present a novel architecture in which a digital processor receives data from an analog-to-digital converter, and writes that data directly to hard drives, without the need for a personal computer to serve as an intermediary in the DAQ process. This minimalist architecture may support exceptionally high data throughput, without incurring costs to support unnecessary hardware and overhead associated with personal computers, thus facilitating scaling of electrophysiological recording in the future.National Institutes of Health (U.S.) (Grant 1DP1NS087724)National Institutes of Health (U.S.) (Grant 1R01DA029639)National Institutes of Health (U.S.) (Grant 1R01NS067199)National Institutes of Health (U.S.) (Grant 2R44NS070453)National Institutes of Health (U.S.) (Grant R43MH101943)New York Stem Cell FoundationPaul Allen FoundationMassachusetts Institute of Technology. Media LaboratoryGoogle (Firm)United States. Defense Advanced Research Projects Agency (HR0011-14-2-0004)Hertz Foundation (Myhrvold Family Fellowship