223 research outputs found

    Inducing Increased Bioplastic Production in \u3ci\u3eR. palustris\u3c/i\u3e CGA009

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    PHA’s (polyhydroxyalkanoates) are important bio polymers in different industries such as petroleum, medicine, and nano technology. In the microorganisms in which they are produced, they serve as an energy storage material by storing both carbon and usable electrons. This is useful in environments where the organisms are nutrient starved. PHA’s have a practical use especially in the medical field as bio-plastics because they are biodegradable and bio-compatible. Rhodopseudomonas. palustris, a common soil bacterium, is notable for its uncommon metabolic flexibility. Its diverse metabolism means that it can fix CO 2 and grow on many lignin based monomers in both aerobic and anaerobic environments. Currently, R. palustris already produces PHB (polyhydroxybutyrate), but there are other PHA’s and co polymers that have superior processing characteristics and applications. Our research will investigate the effect of the PHA production genes from Paraburkholderia sacchari DSM 17165 and Cupriavidus necator DSM 545 when introduced into R. palustris and potentially R. palustris strains with their native PHA production genes knocked out Both P. sacchari and C. necator produce higher titers of PHA’s as well as co polymers with improved processing characteristics and more applications than R. palustris ’ current PHB production. Our research will work to combine the metabolic flexibility of R. palustris with the higher PHA and co polymer production of P sacchari and C. necator by introducing genes for PhaA, PhaB, and PhaC production into R. palustris

    Composition of Primary Cosmic-Ray Nuclei at High Energies

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    The TRACER instrument (``Transition Radiation Array for Cosmic Energetic Radiation'') has been developed for direct measurements of the heavier primary cosmic-ray nuclei at high energies. The instrument had a successful long-duration balloon flight in Antarctica in 2003. The detector system and measurement process are described, details of the data analysis are discussed, and the individual energy spectra of the elements O, Ne, Mg, Si, S, Ar, Ca, and Fe (nuclear charge Z=8 to 26) are presented. The large geometric factor of TRACER and the use of a transition radiation detector make it possible to determine the spectra up to energies in excess of 1014^{14} eV per particle. A power-law fit to the individual energy spectra above 20 GeV per amu exhibits nearly the same spectral index (∼\sim 2.65 ±\pm 0.05) for all elements, without noticeable dependence on the elemental charge Z.Comment: Accepted for publication in the Astrophysical Journal (3-Jan-08), 37 pages, 15 figure

    A new urban freight distribution scheme and an optimization methodology for reducing its overall cost

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    The paper refers to an innovative urban freight distribution scheme, aimed at reducing the externalities connected with the freight delivery process. Both packages destined to commercial activities and to end consumers (e-commerce) are taken into account. Each package is characterized by an address and dimensions. In the proposed transport system, freight is firstly delivered to the UDC on the border of urban areas through trucks or trains which perform the long distance transport. After, freight is reorganized and consolidated into load units, i.e. the FURBOT boxes, according to packages dimensions and to the addresses of receivers. Each box is addressed to a temporary unloading bay and it is delivered there by a FURBOT vehicle. The receivers are in charge of collecting their packages in the related unloading bays where they have been delivered. The paper concerns a methodology for optimizing this freight transport system's performances. The overall methodology receives in input the actual freight demand and the road network, and finds the transport system parameters (number of required FURBOT boxes, their temporary unloading bay, the FURBOT fleet dimension and the FURBOT vehicle routing) that minimize the system overall cost. The overall cost is a sum of the users' cost, which depends on the distance they have to walk for collecting their packages in the FURBOT box, and of the operator's cost, which depends on the number of required boxes, the total distance travelled by the FURBOT vehicles and the required number of FURBOT vehicles. The overall procedure has been applied to the case study of Barreiro old town, a suburb of Lisbon, Portugal

    Firm-Specific Assets, Multinationality, and Financial Performance: A Meta-Analytic Review and Theoretical Integration

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    Through a meta-analysis of 120 independent samples reported in 111 studies, we test the predictions of internalization theory in the context of the multinationality-performance relationship. Findings indicate that multinationality provides an efficient organizational form that enables firms to transfer their firm-specific assets to generate higher returns in international markets. In addition, the results delineate the conditions under which firm-specific assets have the strongest impact on the multinationality-performance relationship. Meta-analytic evidence also suggests that multinationality has intrinsic value above and beyond the intangible assets that firms possess, given analyses controlling for firms\u27 international experience, age, size, and product diversification

    The MACHO Project 9 Million Star Color-Magnitude Diagram of the Large Magellanic Cloud

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    We present a 9 million star color-magnitude diagram (9M CMD) of the LMC bar. The 9M CMD reveals a complex superposition of different age and metallicity stellar populations, with important stellar evolutionary phases occurring over 3 orders of magnitude in number density. First, we count the non-variable supergiants, the associated Cepheids, and measure the effective temperatures defining the instability strip. Lifetime predictions of stellar evolution theory are tested, with implications for the origin of low-luminosity Cepheids. The highly-evolved AGB stars have a bimodal distribution in brightness, which we interpret as discrete old populations (>1 Gyr). The faint AGB may be metal-poor and very old. We identify the clusters NGC 411 and M3 as templates for the admixture of old stellar populations. However, there are indications that the old and metal-poor field population has a red HB morphology: the RR Lyraes lie on the red edge of the instability strip, the AGB-bump is very red, and the ratio of AGB-bump stars to RR Lyraes is quite large. If the HB second parameter is age, the old and metal-poor field population likely formed after the oldest clusters. Lifetime predictions of stellar evolution theory lead us to associate a significant fraction of the red HB clump giants with the same old and metal-poor population producing the RR Lyraes and the AGB-bump. In this case, compared to the age-dependent luminosity predictions of stellar evolution theory, the red HB clump is too bright relative to the RR Lyraes and AGB-bump. Last, the surface density profile of RR Lyraes is fit by an exponential, favoring a disk-like rather than spheroidal distribution. We conclude that the age of the LMC disk is probably similar to the age of the Galactic disk. (ABRIDGED)Comment: to appear in the Astronomical Journal, 49 pages, 12 figures, aaspp4.st

    First Nearglobal Retrievals of OH Rotational Temperatures From Satellite-based Meinel Band Emission Measurements

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    For the first time near-global retrievals of mesopause OH rotational temperatures from satellite-borne Meinel band emission measurements are presented. The measurements of the OH (3-1) Meinel band near 1.5 micron were performed with the SCIAMACHY instrument on the European Space Agency’s environmental satellite Envisat. The derived OH (3-1) rotational temperatures are shown to be in reasonable agreement with the CIRA (1986) atmosphere temperatures for the seasons and latitudes considered. The derived temperatures are in good agreement with groundbased measurements of the OH rotational temperature performed with a CEDAR Mesospheric Temperature Mapper (MTM) at Maui, Hawaii (21N/204E), with the GRound based Infrared P-branch Spectrometer I (GRIPS-I) at Hohenpeißenberg (47N/11E) and with GRIPS-II at Wuppertal (51N/7E). The SCIAMACHY limb nighttime observations provide a unique data set of near-global OH rotational temperature to study seasonal and geographical variations, dynamical processes and possibly long-term temperature trends, if an extended data set becomes available in the future

    Observation of a J^PC = 1-+ exotic resonance in diffractive dissociation of 190 GeV/c pi- into pi- pi- pi+

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    The COMPASS experiment at the CERN SPS has studied the diffractive dissociation of negative pions into the pi- pi- pi+ final state using a 190 GeV/c pion beam hitting a lead target. A partial wave analysis has been performed on a sample of 420000 events taken at values of the squared 4-momentum transfer t' between 0.1 and 1 GeV^2/c^2. The well-known resonances a1(1260), a2(1320), and pi2(1670) are clearly observed. In addition, the data show a significant natural parity exchange production of a resonance with spin-exotic quantum numbers J^PC = 1-+ at 1.66 GeV/c^2 decaying to rho pi. The resonant nature of this wave is evident from the mass-dependent phase differences to the J^PC = 2-+ and 1++ waves. From a mass-dependent fit a resonance mass of 1660 +- 10+0-64 MeV/c^2 and a width of 269+-21+42-64 MeV/c^2 is deduced.Comment: 7 page, 3 figures; version 2 gives some more details, data unchanged; version 3 updated authors, text shortened, data unchange

    Jitter-correction for IR/UV-XUV pump-probe experiments at the FLASH free-electron laser

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    Citation: Savelyev, E., Boll, R., Bomme, C., Schirmel, N., Redlin, H., Erk, B., . . . Rolles, D. (2017). Jitter-correction for IR/UV-XUV pump-probe experiments at the FLASH free-electron laser. New Journal of Physics, 19, 13. doi:10.1088/1367-2630/aa652dIn pump-probe experiments employing a free-electron laser (FEL) in combination with a synchronized optical femtosecond laser, the arrival-time jitter between the FEL pulse and the optical laser pulse often severely limits the temporal resolution that can be achieved. Here, we present a pump-probe experiment on the UV-induced dissociation of 2,6-difluoroiodobenzene (C6H3F2I) molecules performed at the FLASH FEL that takes advantage of recent upgrades of the FLASH timing and synchronization system to obtain high-quality data that are not limited by the FEL arrival-time jitter. Wediscuss in detail the necessary data analysis steps and describe the origin of the timedependent effects in the yields and kinetic energies of the fragment ions that we observe in the experiment

    Energy Flow in the Hadronic Final State of Diffractive and Non-Diffractive Deep-Inelastic Scattering at HERA

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    An investigation of the hadronic final state in diffractive and non--diffractive deep--inelastic electron--proton scattering at HERA is presented, where diffractive data are selected experimentally by demanding a large gap in pseudo --rapidity around the proton remnant direction. The transverse energy flow in the hadronic final state is evaluated using a set of estimators which quantify topological properties. Using available Monte Carlo QCD calculations, it is demonstrated that the final state in diffractive DIS exhibits the features expected if the interaction is interpreted as the scattering of an electron off a current quark with associated effects of perturbative QCD. A model in which deep--inelastic diffraction is taken to be the exchange of a pomeron with partonic structure is found to reproduce the measurements well. Models for deep--inelastic epep scattering, in which a sizeable diffractive contribution is present because of non--perturbative effects in the production of the hadronic final state, reproduce the general tendencies of the data but in all give a worse description.Comment: 22 pages, latex, 6 Figures appended as uuencoded fil

    Placebo Response of Non-Pharmacological and Pharmacological Trials in Major Depression: A Systematic Review and Meta-Analysis

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    Background: Although meta-analyses have shown that placebo responses are large in Major Depressive Disorder (MDD) trials; the placebo response of devices such as repetitive transcranial magnetic stimulation (rTMS) has not been systematically assessed. We proposed to assess placebo responses in two categories of MDD trials: pharmacological (antidepressant drugs) and non-pharmacological (device- rTMS) trials. Methodology/Principal Findings: We performed a systematic review and meta-analysis of the literature from April 2002 to April 2008, searching MEDLINE, Cochrane, Scielo and CRISP electronic databases and reference lists from retrieved studies and conference abstracts. We used the keywords placebo and depression and escitalopram for pharmacological studies; and transcranial magnetic stimulation and depression and sham for non-pharmacological studies. All randomized, double-blinded, placebo-controlled, parallel articles on major depressive disorder were included. Forty-one studies met our inclusion criteria - 29 in the rTMS arm and 12 in the escitalopram arm. We extracted the mean and standard values of depression scores in the placebo group of each study. Then, we calculated the pooled effect size for escitalopram and rTMS arm separately, using Cohen's d as the measure of effect size. We found that placebo response are large for both escitalopram (Cohen's d - random-effects model - 1.48; 95%C.I. 1.26 to 1.6) and rTMS studies (0.82; 95%C.I. 0.63 to 1). Exploratory analyses show that sham response is associated with refractoriness and with the use of rTMS as an add-on therapy, but not with age, gender and sham method utilized. Conclusions/Significance: We confirmed that placebo response in MDD is large regardless of the intervention and is associated with depression refractoriness and treatment combination (add-on rTMS studies). The magnitude of the placebo response seems to be related with study population and study design rather than the intervention itself
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