14,495 research outputs found
Right-Handed Quark Mixings in Minimal Left-Right Symmetric Model with General CP Violation
We present a systematic approach to solve analytically for the right-handed
quark mixings in the minimal left-right symmetric model which generally has
both explicit and spontaneous CP violations. The leading-order result has the
same hierarchical structure as the left-handed CKM mixing, but with additional
CP phases originating from a spontaneous CP-violating phase in the Higgs vev.
We explore the phenomenology entailed by the new right-handed mixing matrix,
particularly the bounds on the mass of and the CP phase of the Higgs vev.Comment: 8 pages, one postscript figure include
Second-order Nonlinear Optical Microscopy of Spider Silk
Asymmetric -sheet protein structures in spider silk should induce
nonlinear optical interaction such as second harmonic generation (SHG) which is
experimentally observed for a radial line and dragline spider silk by using an
imaging femtosecond laser SHG microscope. By comparing different spider silks,
we found that the SHG signal correlates with the existence of the protein -sheets. Measurements of the polarization dependence of SHG from the
dragline indicated that the -sheet has a nonlinear response
depending on the direction of the incident electric field. We propose a model
of what orientation the -sheet takes in spider silk.Comment: 8 pages, 8 figures, 1 tabl
Single production of new gauge bosons from the littlest Higgs model at the energy colliders
In the context of the littlest Higgs(LH) model, we study single production of
the new gauge bosons , and via
collisions and discuss the possibility of detecting these new particles in the
energy collider(). We find that these new particles can
not be detected via the signal in all of the parameter space
preferred by the electroweak precision data. However, the heavy gauge bosons
and may be observed via the decay channel in wide range of the parameter space.Comment: references added, typos corrected. To be published in Phys. Rev.
Ozone vegetation damage effects on gross primary productivity in the United States
This is the final version. Available on open access from EGU via the DOI in this recordWe apply an off-line process-based vegetation model (the Yale Interactive Terrestrial Biosphere model) to assess the impacts of ozone (O3) vegetation damage on gross primary productivity (GPP) in the United States during the past decade (1998-2007). The model's GPP simulation is evaluated at 40 sites of the North American Carbon Program (NACP) synthesis. The ecosystem-scale model version reproduces interannual variability and seasonality of GPP at most sites, especially in croplands. Inclusion of the O3damage impact decreases biases of simulated GPP at most of the NACP sites. The simulation with the O3damage effect reproduces 64% of the observed variance in summer GPP and 42% on the annual average. Based on a regional gridded simulation over the US, summertime average O3-free GPP is 6.1 g Cm-2day-1(9.5 g Cm-2day-1in the east of 95° W and 3.9 g Cm-2day-1in the west). O3damage decreases GPP by 4-8% on average in the eastern US and leads to significant decreases of 11-17% in east coast hot spots. Sensitivity simulations show that a 25% decrease in surface O3concentration halves the average GPP damage to only 2-4 %, suggesting the substantial co-benefits to ecosystem health that may be achieved via O3air pollution control.Funding for this research was provided by
Yale Universit
Strong chemistry-climate feedbacks in the Pliocene
This is the final version. Available on open access from AGU via the DOI in this recordThe Pliocene epoch was the last sustained interval when global climate was significantly warmer than today but has been difficult to explain fully based on the external forcings from atmospheric carbon dioxide and surface albedo. Here we use an Earth system model to simulate terrestrial ecosystem emissions and atmospheric chemical composition in the mid-Pliocene (about 3 million years ago) and the preindustrial (∼1750s). Tropospheric ozone and aerosol precursors from vegetation and wildfire are ∼50% and ∼100% higher in the mid-Pliocene due to the spread of the tropical savanna and deciduous biomes. The chemistry-climate feedbacks contribute a net global warming that is +30-250% of the carbon dioxide effect and a net aerosol global cooling that masks 15-100% of the carbon dioxide effect. These large vegetation-mediated ozone and aerosol feedbacks operate on centennial to millennial timescales in the climate system and have not previously been included in paleoclimate sensitivity assessments.Funding for this research is provided by Yale University
Sum frequency generation spectroscopy of the attachment disc of a spider
The pyriform silk of the attachment disc of a spider was studied using
infrared-visible vibrational sum frequency generation (SFG) spectroscopy. The
spider can attach dragline and radial lines to many kinds of substrates in
nature (concrete, alloy, metal, glass, plant branches, leaves, etc.) with the
attachment disc. The adhesion can bear the spider's own weight, and resist the
wind on its orb web. From our SFG spectroscopy study, the NH group of arginine
side chain and/or NH group of arginine and glutamine side chain in the
amino acid sequence of the attachment silk proteins are suggested to be
oriented in the disc. It was inferred from the observed doublet SFG peaks at
around 3300 cm that the oriented peptide contains two kinds of
structures.Comment: 21 pages, 8 figure
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