849 research outputs found
Effect of pyramiding Bt and CpTI genes on resistance of cotton to Helicoverpa armigera (Lepidoptera: Noctuidae) under laboratory and field conditions
Transgenic cotton (Gossypium hirsutum L.) varieties, adapted to China, have been bred that express two genes for resistance to insects. the Cry1Ac gene from Bacillus thuringiensis (Berliner) (Bt), and a trypsin inhibitor gene from cowpea (CpTI). Effectiveness of the double gene modification in conferring resistance to cotton bollworm, Helicoverpa armigera (Hübner) (Lepidoptera: Noctuidae), was studied in laboratory and field experiments. In each experiment, performance of Bt+CpTI cotton was compared with Bt cotton and to a conventional nontransgenic variety. Larval survival was lower on both types of transgenic variety, compared with the conventional cotton. Survival of first-, second-, and third-stage larvae was lower on Bt+CpTI cotton than on Bt cotton. Plant structures differed in level of resistance, and these differences were similar on Bt and Bt+CpTI cotton. Likewise, seasonal trends in level of resistance in different plant structures were similar in Bt and Bt+CpTI cotton. Both types of transgenic cotton interfered with development of sixth-stage larvae to adults, and no offspring was produced by H. armigera that fed on Bt or Bt+CpTI cotton from the sixth stage onward. First-, second-, and third-stage larvae spent significantly less time feeding on transgenic cotton than on conventional cotton, and the reduction in feeding time was significantly greater on Bt+CpTI cotton than on Bt cotton. Food conversion efficiency was lower on transgenic varieties than on conventional cotton, but there was no significant difference between Bt and Bt+CpTI cotton. In 3-yr field experimentation, bollworm densities were greatly suppressed on transgenic as compared with conventional cotton, but no significant differences between Bt and Bt+CpTI cotton were found. Overall, the results from laboratory work indicate that introduction of the CpTI gene in Bt cotton raises some components of resistance in cotton against H. armigera, but enhanced control of H. armigera under field conditions, due to expression of the CpTI gene, was not demonstrate
Provenance and evolution of East Asian large rivers recorded in the East and South China Seas: A review
Large rivers are the arteries of continents. Those originating from the Tibetan Plateau and traversing East Asia have a relatively young history due to continuous Cenozoic perturbations. However, it has been a long journey to reconstruct their genesis and dynamic evolution, in which many puzzles and challenges remain. The river history is documented by provenance information in the ultimate sediment sinks in the East and South China Seas, but a regional-scale correlation of provenance data is still developing. Here, we explore the promise of this provenance perspective by reconstructing the evolution of three large rivers in China (the Yangtze, Pearl, and Red Rivers) by compiling and reevaluating a large volume of published provenance data (zircon U-Pb geochronology, K-feldspar Pb isotopes, and whole-rock Nd isotopes) from both Cenozoic strata and modern sediments from the East and South China Seas and the large river basins. Unlike traditional approaches that average provenance signatures, intersample variability was carefully evaluated. The general inheritance of zircon age spectral patterns and small fluctuations of Nd isotopes in the Neogene strata suggest provenance stabilization in the East and South China Seas and the establishment of near-modern drainage configurations. The paleodrainage basins before the Miocene are interpreted to have been smaller than their modern sizes, and drainage expansion likely occurred over the Oligocene. Our analysis suggests that the widely accepted models that link drainage between the ancient Yangtze and Red Rivers may be unlikely. The compiled provenance signatures and prior paleocurrent measurements of Paleogene strata distributed in the southeastern Tibetan Plateau margin show sediment supplied from local terranes instead of through-flowing river systems
Abelian Hidden Sectors at a GeV
We discuss mechanisms for naturally generating GeV-scale hidden sectors in
the context of weak-scale supersymmetry. Such low mass scales can arise when
hidden sectors are more weakly coupled to supersymmetry breaking than the
visible sector, as happens when supersymmetry breaking is communicated to the
visible sector by gauge interactions under which the hidden sector is
uncharged, or if the hidden sector is sequestered from gravity-mediated
supersymmetry breaking. We study these mechanisms in detail in the context of
gauge and gaugino mediation, and present specific models of Abelian GeV-scale
hidden sectors. In particular, we discuss kinetic mixing of a U(1)_x gauge
force with hypercharge, singlets or bi-fundamentals which couple to both
sectors, and additional loop effects. Finally, we investigate the possible
relevance of such sectors for dark matter phenomenology, as well as for low-
and high-energy collider searches.Comment: 43 pages, no figures; v2: to match JHEP versio
Associations between personal apparent temperature exposures and asthma symptoms in children with asthma
Ambient temperature and relative humidity can affect asthma symptoms. Apparent temperature is a measure of temperature perceived by humans that takes into account the effect of humidity. However, the potential link between personal exposures to apparent temperature and asthma symptoms has not been investigated. We conducted a panel study of 37 asthmatic children, aged 5–11 years, during an early spring season (average daily ambient temperature: 14C, range: 7–18C). Asthma symptoms were measured 4 times for each participant with a 2-week interval between consecutive measurements using the Childhood Asthma-Control Test (C-ACT). Average, minimum, and maximum personal apparent temperature exposures, apparent temperature exposure variability (TV), and average ambient temperature were calculated for the 12 hours, 24 hours, week, and 2 weeks prior to each visit. We found that a 10C lower in 1-week and 2-week average & minimum personal apparent temperature exposures, TV, and average ambient temperature exposures were significantly associated with lower total C-ACT scores by up to 2.2, 1.4, 3.3, and 1.4 points, respectively, indicating worsened asthma symptoms. Our results support that personal apparent temperature exposure is potentially a stronger driver than ambient temperature exposures for the variability in asthma symptom scores. Maintaining a proper personal apparent temperature exposure could be an effective strategy for personalized asthma management. Copyright: This is an open access article, free of all copyright, and may be freely reproduced, distributed, transmitted, modified, built upon, or otherwise used by anyone for any lawful purpose
Evolution of cosmic superstring networks: a numerical simulation
We study the formation and evolution of an interconnected string network in
large-scale field-theory numerical simulations, both in flat spacetime and in
expanding universe. The network consists of gauge U(1) strings of two different
kinds and their bound states, arising due to an attractive interaction
potential. We find that the network shows no tendency to ``freeze'' and appears
to approach a scaling regime, with all characteristic lengths growing linearly
with time. Bound strings constitute only a small fraction of the total string
length in the network.Comment: 16 pages, 13 figures; Minor changes; Matches published versio
Measurement of (anti)deuteron and (anti)proton production in DIS at HERA
The first observation of (anti)deuterons in deep inelastic scattering at HERA
has been made with the ZEUS detector at a centre-of-mass energy of 300--318 GeV
using an integrated luminosity of 120 pb-1. The measurement was performed in
the central rapidity region for transverse momentum per unit of mass in the
range 0.3<p_T/M<0.7. The particle rates have been extracted and interpreted in
terms of the coalescence model. The (anti)deuteron production yield is smaller
than the (anti)proton yield by approximately three orders of magnitude,
consistent with the world measurements.Comment: 26 pages, 9 figures, 5 tables, submitted to Nucl. Phys.
The yields of r-process elements and chemical evolution of the Galaxy
The supernova yields of r-process elements are obtained as a function of the
mass of their progenitor stars from the abundance patterns of extremely
metal-poor stars on the left-side [Ba/Mg]-[Mg/H] boundary with a procedure
proposed by Tsujimoto and Shigeyama. The ejected masses of r-process elements
associated with stars of progenitor mass are infertile
sources and the SNe II with 20are the
dominant source of r-process nucleosynthesis in the Galaxy. The ratio of these
stars 20 with compared to the all massive
stars is about 18%. In this paper, we present a simple model that
describes a star's [r/Fe] in terms of the nucleosynthesis yields of r-process
elements and the number of SN II explosions. Combined the r-process yields
obtained by our procedure with the scatter model of the Galactic halo, the
observed abundance patterns of the metal-poor stars can be well reproducedComment: 7 pages, 6 figures, Accepted for publication in Astrophysics and
Space Scienc
Forward jet production in deep inelastic ep scattering and low-x parton dynamics at HERA
Differential inclusive jet cross sections in neutral current deep inelastic
ep scattering have been measured with the ZEUS detector. Three phase-space
regions have been selected in order to study parton dynamics where the effects
of BFKL evolution might be present. The measurements have been compared to the
predictions of leading-logarithm parton shower Monte Carlo models and
fixed-order perturbative QCD calculations. In the forward region, QCD
calculations at order alpha_s^1 underestimate the data up to an order of
magnitude at low x. An improved description of the data in this region is
obtained by including QCD corrections at order alpha_s^2, which account for the
lowest-order t-channel gluon-exchange diagrams, highlighting the importance of
such terms in parton dynamics at low x.Comment: 25 pages, 4 figure
Quantum Dots and Wires to improve Enzymes-Based Electrochemical Bio- sensing
An investigation on nano-structured electrodes to detect different metabolites is proposed in this paper. Three different metabolites are considered: glucose, lactate, and cholesterol. The direct detection of hydrogen peroxide is also considered since it does not involve any enzyme. The metabolites and the peroxide were detected by using screen-printed electrodes modified by using multi-walled carbon nanotubes. In all cases, improvements of orders of magnitude were registered both on detection sensitivity and on detection limit. A close comparison with data recently published in literature has shown the existence of an inverse linear correlation between detection sensitivity and detection limit when sensor performances improve due to nano- structured materials. This inverse linear relationship seems to be a general law as it is here demonstrated for all the considered detections on glucose, lactate, cholesterol, and hydrogen peroxide
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