Probing the cosmic star formation using long Gamma-Ray Bursts: New constraints from the Spitzer Space Telescope

We report on IRAC-4.5mic, IRAC-8.0mic and MIPS-24mic deep observations of 16 Gamma-Ray Burst (GRBs) host galaxies performed with the Spitzer Space Telescope, and we investigate in the thermal infrared the presence of evolved stellar populations and dust-enshrouded star-forming activity associated with these objects. Our sample is derived from GRBs that were identified with sub-arcsec localization between 1997 and 2001, and only a very small fraction (~20%) of the targeted sources is detected down to f_4.5mic ~3.5microJy and f_24mic ~85microJy (3sigma). This likely argues against a population dominated by massive and strongly-starbursting (i.e., SFR > ~100 Msol/yr) galaxies as it has been recently suggested from submillimeter/radio and optical studies of similarly-selected GRB hosts. Furthermore we find evidence that some GRBs do not occur in the most infrared-luminous regions -- hence the most actively star-forming environments -- of their host galaxies. Should the GRB hosts be representative of all star-forming galaxies at high redshift, models of infrared galaxy evolution indicate that > ~50% of GRB hosts should have f_24mic > ~100microJy. Unless the identification of GRBs prior to 2001 was prone to strong selection effects biasing our sample against dusty galaxies, we infer in this context that the GRBs identified with the current techniques can not be directly used as unbiased probes of the global and integrated star formation history of the Universe.Comment: ApJ in press, 23 pages, 8 figures (scheduled for the ApJ 10 May 2006, v642 2 issue). Full resolution available at http://perceval.as.arizona.edu/~elefloch/Publis/ms_grb_spitzer.pd

Geologic controls on submarine slope failure along the central U.S. Atlantic margin : insights from the Currituck Slide Complex

© The Author(s), 2016. This is the author's version of the work and is distributed under the terms of the Creative Commons Attribution License. The definitive version was published in Marine Geology 385 (2017): 114-130, doi:10.1016/j.margeo.2016.10.007.Multiple styles of failure, ranging from densely spaced, mass transport driven canyons to the large, slab-type slope failure of the Currituck Slide, characterize adjacent sections of the central U.S. Atlantic margin that appear to be defined by variations in geologic framework. Here we use regionally extensive, deep penetration multichannel seismic (MCS) profiles to reconstruct the influence of the antecedent margin physiography on sediment accumulation along the central U.S. Atlantic continental shelf-edge, slope, and uppermost rise from the Miocene to Present. These data are combined with highresolution sparker MCS reflection profiles and multibeam bathymetry data across the Currituck Slide complex. Pre-Neogene allostratigraphic horizons beneath the slope are generally characterized by low gradients and convex downslope profiles. This is followed by the development of thick, prograded deltaic clinoforms during the middle Miocene. Along-strike variations in morphology of a regional unconformity at the top of this middle Miocene unit appear to have set the stage for differing styles of mass transport along the margin. Areas north and south of the Currituck Slide are characterized by oblique margin morphology, defined by an angular shelf-edge and a relatively steep (>8°), concave slope profile. Upper slope sediment bypass, closely spaced submarine canyons, and small, localized landslides confined to canyon heads and sidewalls characterize these sectors of the margin. In contrast, the Currituck region is defined by a sigmoidal geometry, with a rounded shelf-edge rollover and gentler slope gradient (<6°). Thick (>800 m), regionally continuous stratified slope deposits suggest the low gradient Currituck region was a primary depocenter for fluvial inputs during multiple sea level lowstands. These results imply that the rounded, gentle slope physiography developed during the middle Miocene allowed for a relatively high rate of subsequent sediment accumulation, thus providing a mechanism for compaction–induced overpressure that preconditioned the Currituck region for failure. Detailed examination of the regional geological framework illustrates the importance of both sediment supply and antecedent slope physiography in the development of large, potentially unstable depocenters along passive margins.The U.S. Geological Survey, the U.S. Nuclear Regulatory Commission and Coastal Carolina University funded this research

Public Attitudes on Transgender Military Service: The Role of Gender

Policy regarding the inclusion of transgender soldiers in the U.S. military has shifted back and forth in recent years, with public opinion likely a significant factor shaping the eventual policy outcome. As such, this study examines the factors that shape public attitudes toward military service by transgender people. In particular, we examine the influence of sex, social gender roles, and attitudes toward gender in shaping transgender military service attitudes. Further, we hypothesize that personal experiences with the military and with transgender people, along with values, personality predispositions, and religion, are likely to influence individual attitudes. We test these hypotheses using data from a unique October 2015 national survey of American adults. The results suggest that personal experiences, attitudes toward gender roles, and religion have substantial, but sometimes conditional effects on attitudes towards military service by transgender people.University of toledoUniversity of KansasUCLA school of lawOhio Universit

Factorial design for preparing chitosan nanoparticles and its use for loading and controlled release of indole-3-acetic acid with effect on hydroponic lettuce crops

The excessive use of agrochemicals generates damage to the environment, so their controlled release from biodegradable nanoparticles represents a good solution. In this study, chitosan nanoparticles (CNPs) were prepared by ionic gelation with sodium tripolyphosphate (TPP), according to a 24 factorial design to evaluate the effect of different factors (chitosan amount, TPP amount, agitation speed, and agitation time) influencing the nanoparticle size (NPS) and the polydispersity index (PDI). Once established the proper conditions by the factorial design, CNPs were prepared and loaded with indole-3-acetic acid (CNP-IAA). The nanoparticles loaded with chitosan:IAA mass ratio equal to 1:0.25, showed the higher loading capacity, thus were then used for the release tests and hydroponic lettuces crops. The analysis by dynamic light scattering (DLS) reveals a mean diameter for CNPs and CNP-IAA of ~149 and ~183 nm, respectively. Moreover, further characterization by thermogravimetric analysis, Fourier transform infrared spectroscopy and scanning electron microscopy, indicates that nanoparticles were effectively loaded with IAA. In addition, the release assays results were adjusted to the Korsmeyers-Peppas mathematical model, showing that 100% of the hormone is released in about 48 h. Also, the model fitting suggests that the release process is carried out in two steps: the first of releasing by diffusion followed by a second of sustained-release. Accordingly, our results prove that CNPs-IAA applied to the hydroponic crop of the Crocantela variety crisp lettuce (Latuca sativa L.), have a beneficial effect on the plant growth producing an increase of 30.9% in the number of lettuce leaves

Two highly divergent alcohol dehydrogenases of melon exhibit fruit ripening-specific expression and distinct biochemical characteristics

Alcohol dehydrogenases (ADH) participate in the biosynthetic pathway of aroma volatiles in fruit by interconverting aldehydes to alcohols and providing substrates for the formation of esters. Two highly divergent ADH genes (15% identity at the amino acid level) of Cantaloupe Charentais melon (Cucumis melo var. Cantalupensis) have been isolated. Cm-ADH1 belongs to the medium-chain zinc-binding type of ADHs and is highly similar to all ADH genes expressed in fruit isolated so far. Cm-ADH2 belongs to the short-chain type of ADHs. The two encoded proteins are enzymatically active upon expression in yeast. Cm-ADH1 has strong preference for NAPDH as a co-factor, whereas Cm-ADH2 preferentially uses NADH. Both Cm-ADH proteins are much more active as reductases with Kms 10–20 times lower for the conversion of aldehydes to alcohols than for the dehydrogenation of alcohols to aldehydes. They both show strong preference for aliphatic aldehydes but Cm-ADH1 is capable of reducing branched aldehydes such as 3-methylbutyraldehyde, whereas Cm-ADH2 cannot. Both Cm-ADH genes are expressed specifically in fruit and up-regulated during ripening. Gene expression as well as total ADH activity are strongly inhibited in antisense ACC oxidase melons and in melon fruit treated with the ethylene antagonist 1-methylcyclopropene (1-MCP), indicating a positive regulation by ethylene. These data suggest that each of the Cm-ADH protein plays a specific role in the regulation of aroma biosynthesis in melon fruit

Experimental and quantum chemical studies of a novel synthetic prenylated chalcone

BACKGROUND: Chalcones are ubiquitous natural compounds with a wide variety of reported biological activities, including antitumoral, antiviral and antimicrobial effects. Furthermore, chalcones are being studied for its potential use in organic electroluminescent devices; therefore the description of their spectroscopic properties is important to elucidate the structure of these molecules. One of the main techniques available for structure elucidation is the use of Nuclear Magnetic Resonance Spectroscopy (NMR). Accordingly, the prediction of the NMR spectra in this kind of molecules is necessary to gather information about the influence of substituents on their spectra. RESULTS: A novel substituted chalcone has been synthetized. In order to identify the functional groups present in the new synthesized compound and confirm its chemical structure, experimental and theoretical (1)H-NMR and (13)C-NMR spectra were analyzed. The theoretical molecular structure and NMR spectra were calculated at both the Hartree-Fock and Density Functional (meta: TPSS; hybrid: B3LYP and PBE1PBE; hybrid meta GGA: M05-2X and M06-2X) levels of theory in combination with a 6-311++G(d,p) basis set. The structural parameters showed that the best method for geometry optimization was DFT:M06-2X/6-311++G(d,p), whereas the calculated bond angles and bond distances match experimental values of similar chalcone derivatives. The NMR calculations were carried out using the Gauge-Independent Atomic Orbital (GIAO) formalism in a DFT:M06-2X/6-311++G(d,p) optimized geometry. CONCLUSION: Considering all HF and DFT methods with GIAO calculations, TPSS and PBE1PBE were the most accurate methods used for calculation of (1)H-NMR and (13)C-NMR chemical shifts, which was almost similar to the B3LYP functional, followed in order by HF, M05-2X and M06-2X methods. All calculations were done using the Gaussian 09 software package. Theoretical calculations can be used to predict and confirm the structure of substituted chalcones with good correlation with the experimental data

Seabed fluid expulsion along the upper slope and outer shelf of the U.S. Atlantic continental margin

Author Posting. © American Geophysical Union, 2014. This article is posted here by permission of American Geophysical Union for personal use, not for redistribution. The definitive version was published in Geophysical Research Letters 41 (2014): 96-101, doi:10.1002/2013GL058048.Identifying the spatial distribution of seabed fluid expulsion features is crucial for understanding the substrate plumbing system of any continental margin. A 1100 km stretch of the U.S. Atlantic margin contains more than 5000 pockmarks at water depths of 120 m (shelf edge) to 700 m (upper slope), mostly updip of the contemporary gas hydrate stability zone (GHSZ). Advanced attribute analyses of high-resolution multichannel seismic reflection data reveal gas-charged sediment and probable fluid chimneys beneath pockmark fields. A series of enhanced reflectors, inferred to represent hydrate-bearing sediments, occur within the GHSZ. Differential sediment loading at the shelf edge and warming-induced gas hydrate dissociation along the upper slope are the proposed mechanisms that led to transient changes in substrate pore fluid overpressure, vertical fluid/gas migration, and pockmark formation.The U.S. Geological Survey and the U.S. Nuclear Regulatory Commission funded this research.2014-07-0

Mechanical and electrical properties of additively manufactured copper

Additive Manufacturing (AM) has become the new paradigm of design and production strategies. While structural and functional materials are the most implemented ones, it is also possible to manufacture parts using precious metals, being copper one of the most interesting. Among AM technologies, the novel Atomic Diffusion Additive Manufacturing (ADAM) hasrecently included this material between available ones. ADAM is free from thermal and energetic issues caused by high reflectivity and conductivity of copper which other AM encounter. Therefore, it could be a great alternative to manufacture pure copper. In this work ADAM was used to fabricate pure copper specimens in order to measure electrical and mechanical properties. The influence of a machining post processes in strength and ductility is also discussed. Results are compared with wrought C1 1000 copper and published results of other AM technologies. Despite the newness of ADAM, significant improvement in surface roughness and comparable results in other properties was observed. However, further research shall be done to optimize the manufacturing parameters in order to increase the relative density value, as it was found to be significantly lower than in other AM technologies

Functional characterization of a melon alcohol acyl-transferase gene family involved in the biosynthesis of ester volatiles. Identification of the crucial role of a threonine residue for enzyme activity

Volatile esters, a major class of compounds contributing to the aroma of many fruit, are synthesized by alcohol acyl-transferases (AAT). We demonstrate here that, in Charentais melon (Cucumis melo var. cantalupensis), AAT are encoded by a gene family of at least four members with amino acid identity ranging from 84% (Cm-AAT1/Cm-AAT2) and 58% (Cm-AAT1/Cm-AAT3) to only 22% (Cm-AAT1/Cm-AAT4). All encoded proteins, except Cm-AAT2, were enzymatically active upon expression in yeast and show differential substrate preferences. Cm-AAT1 protein produces a wide range of short and long-chain acyl esters but has strong preference for the formation of E-2-hexenyl acetate and hexyl hexanoate. Cm-AAT3 also accepts a wide range of substrates but with very strong preference for producing benzyl acetate. Cm-AAT4 is almost exclusively devoted to the formation of acetates, with strong preference for cinnamoyl acetate. Site directed mutagenesis demonstrated that the failure of Cm-AAT2 to produce volatile esters is related to the presence of a 268-alanine residue instead of threonine as in all active AAT proteins. Mutating 268-A into 268-T of Cm-AAT2 restored enzyme activity, while mutating 268-T into 268-A abolished activity of Cm-AAT1. Activities of all three proteins measured with the prefered substrates sharply increase during fruit ripening. The expression of all Cm-AAT genes is up-regulated during ripening and inhibited in antisense ACC oxidase melons and in fruit treated with the ethylene antagonist 1-methylcyclopropene (1-MCP), indicating a positive regulation by ethylene. The data presented in this work suggest that the multiplicity of AAT genes accounts for the great diversity of esters formed in melon