Control of polarization and mode mapping of small volume high Q micropillars

We show that the polarization of the emission of a single quantum dot embedded within a microcavity pillar of elliptical cross section can be completely controlled and even switched between two orthogonal linear polarizations by changing the coupling of the dot emission with the polarized photonic modes. We also measure the spatial profle of the emission of a series of pillars with different ellipticities and show that the results can be well described by simple theoretical modeling of the modes of an infinite length elliptical cylinder

Comparative effect of lodging on seed yield of flax and wheat

Non-Peer Reviewe

Relative performance of four midge-resistant wheat varietal blends in western Canada

Non-Peer ReviewedOrange wheat blossom midge, Sitodiplosis mosellana (Géhin), causes significant yield losses to spring wheat in western Canada in severe infestations. To mitigate losses, midge-resistant wheat varietal blends, consisting of cultivars carrying the Sm1 midge resistance gene and 10% interspersed midge susceptible refuge, have been made available to farmers. To test their performance relative to conventional midge-susceptible cultivars, four varietal blends were grown during four consecutive years, at eight locations in the provinces of Manitoba Saskatchewan and Alberta, in comparison to four conventional, midge-susceptible cultivars. Midge damage was higher in 2007 and 2010 than in 2008 and 2009. In general, the varietal blends, as a group, yielded more grain than the susceptible cultivars, especially when grown in environments with high midge pressure (5.5 - 35% seed damage). In environments with low midge pressure (0 – 2.6% seed damage), the varietal blend average yield advantage was smaller but still significant, indicating that some of the varietal blends had additional superior attributes, in addition to midge resistance

The effect of incorporating the midge resistance (Sm1) gene in wheat

Non-Peer ReviewedOrange wheat blossom midge, Sitodiplosis mosellana (Géhin), was first detected in Manitoba in 1901, but now is present in all three prairie provinces of western Canada. In severe infestations, this insect may cause significant yield losses to spring wheat. To mitigate losses, midge-resistant wheat varietal blends, consisting of cultivars carrying the Sm1 midge resistance gene and 10% interspersed midge susceptible refuge, are now available to farmers. The refuge prevents this resistance to be overcome by the insect. To test the field performance of these varietal blends, relative to conventional midge-susceptible cultivars, four varietal blends were grown during four consecutive years, at eight locations in the provinces of Manitoba Saskatchewan and Alberta, in comparison to four conventional, midge-susceptible cultivars. Midge damage was higher in 2007 and 2010, than in 2008 and 2009. In general, the varietal blends, as a group, yielded more grain than the susceptible cultivars, especially when grown in environments with high midge pressure (5.5 - 35% seed damage). In environments with low midge pressure (0 – 2.6% seed damage), the varietal blend average yield advantage was smaller but still significant, indicating that some of the varietal blends had additional superior attributes, in addition to midge resistance. Significant differences in midge damage were observed within the resistant and the susceptible groups of the cultivars tested. Midge resistance did not protect wheat against loss of market grade

Precise measurements of radio-frequency magnetic susceptibility in (anti)ferromagnetic materials

Dynamic magnetic susceptibility, $\chi$, was studied in several intermetallic materials exhibiting ferromagnetic, antiferromagnetic and metamagnetic transitions. Precise measurements by using a 14 MHz tunnel diode oscillator (TDO) allow detailed insight into the field and temperature dependence of $\chi$. In particular, local moment ferromagnets show a sharp peak in $\chi(T)$ near the Curie temperature, $T_c$. The peak amplitude decreases and shifts to higher temperatures with very small applied dc fields. Anisotropic measurements of CeVSb$_3$ show that this peak is present provided the magnetic easy axis is aligned with the excitation field. In a striking contrast, small moment, itinerant ferromagnets (i.e., ZrZn$_2$) show a broad maximum in $\chi(T)$ that responds differently to applied field. We believe that TDO measurements provide a very sensitive way to distinguish between local and itinerant moment magnetic orders. Local moment antiferromagnets do not show a peak at the N\'eel temperature, $T_N$, but only a sharp decrease of $\chi$ below $T_N$ due to the loss of spin-disorder scattering changing the penetration depth of the ac excitation field. Furthermore, we show that the TDO is capable of detecting changes in spin order as well as metamagnetic transitions. Finally, critical scaling of $\chi(T,H)$ in the vicinity of $T_C$ is discussed in CeVSb$_3$ and CeAgSb$_2$

Thermal Unparticles: A New Form of Energy Density in the Universe

Unparticle \U with scaling dimension d_\U has peculiar thermal properties due to its unique phase space structure. We find that the equation of state parameter \omega_\U, the ratio of pressure to energy density, is given by 1/(2d_\U +1) providing a new form of energy in our universe. In an expanding universe, the unparticle energy density \rho_\U(T) evolves dramatically differently from that for photons. For d_\U >1, even if \rho_\U(T_D) at a high decoupling temperature $T_D$ is very small, it is possible to have a large relic density \rho_\U(T^0_\gamma) at present photon temperature $T^0_\gamma$, large enough to play the role of dark matter. We calculate $T_D$ and \rho_\U(T^0_\gamma) using photon-unparticle interactions for illustration.Comment: 5 pages; v3, journal version

Using VR to investigate the relationship between visual acuity and severity of simulated oscillopsia

Purpose: Oscillopsia is a debilitating symptom resulting from involuntary eye movement most commonly associated with acquired nystagmus. Investigating and documenting the efects of oscillopsia severity on visual acuity (VA) is challenging. This paper aims to further understanding of the efects of oscillopsia using a virtual reality simulation. Methods: Fifteen right-beat horizontal nystagmus waveforms, with diferent amplitude (1°, 3°, 5°, 8° and 11°) and frequency (1.25 Hz, 2.5 Hz and 5 Hz) combinations, were produced and imported into virtual reality to simulate diferent severities of oscillopsia. Fifty participants without ocular pathology were recruited to read logMAR charts in virtual reality under stationary conditions (no oscillopsia) and subsequently while experiencing simulated oscillopsia. The change in VA (logMAR) was calculated for each oscillopsia simulation (logMAR VA with oscillopsia – logMAR VA with no oscillopsia), removing the inluence of diferent baseline VAs between participants. A one-tailed paired t-test was used to assess statistical signiicance in the worsening in VA caused by the oscillopsia simulations. Results: VA worsened with each incremental increase in simulated oscillopsia intensity (frequency x amplitude), either by increasing frequency or amplitude, with the exception of statistically insigniicant changes at lower intensity simulations. Theoretical understanding predicted a linear relationship between increasing oscillopsia intensity and worsening VA. This was supported by observations at lower intensity simulations but not at higher intensities, with incremental changes in VA gradually levelling of. A potential reason for the diference at higher intensities is the inluence of frame rate when using digital simulations in virtual reality. Conclusions: The frequency and amplitude were found to equally afect VA, as predicted. These results not only consolidate the assumption that VA degrades with oscillopsia but also provide quantitative information that relates these changes to amplitude and frequency of oscillopsia

ATIC and PAMELA Results on Cosmic e^\pm Excesses and Neutrino Masses

Recently the ATIC and PAMELA collaborations released their results which show the abundant e^\pm excess in cosmic rays well above the background, but not for the \bar{p}. Their data if interpreted as the dark matter particles' annihilation imply that the new physics with the dark matter is closely related to the lepton sector. In this paper we study the possible connection of the new physics responsible for the cosmic e^\pm excesses to the neutrino mass generation. We consider a class of models and do the detailed numerical calculations. We find that these models can natually account for the ATIC and PAMELA e^\pm and \bar{p} data and at the same time generate the small neutrino masses.Comment: 7 pages, 5 figures. Published version with minor corrections and more reference

Primary decomposition and the fractal nature of knot concordance

For each sequence of polynomials, P=(p_1(t),p_2(t),...), we define a characteristic series of groups, called the derived series localized at P. Given a knot K in S^3, such a sequence of polynomials arises naturally as the orders of certain submodules of the sequence of higher-order Alexander modules of K. These group series yield new filtrations of the knot concordance group that refine the (n)-solvable filtration of Cochran-Orr-Teichner. We show that the quotients of successive terms of these refined filtrations have infinite rank. These results also suggest higher-order analogues of the p(t)-primary decomposition of the algebraic concordance group. We use these techniques to give evidence that the set of smooth concordance classes of knots is a fractal set. We also show that no Cochran-Orr-Teichner knot is concordant to any Cochran-Harvey-Leidy knot.Comment: 60 pages, added 4 pages to introduction, minor corrections otherwise; Math. Annalen 201