Motion of a vortex line near the boundary of a semi-infinite uniform condensate

We consider the motion of a vortex in an asymptotically homogeneous condensate bounded by a solid wall where the wave function of the condensate vanishes. For a vortex parallel to the wall, the motion is essentially equivalent to that generated by an image vortex, but the depleted surface layer induces an effective shift in the position of the image compared to the case of a vortex pair in an otherwise uniform flow. Specifically, the velocity of the vortex can be approximated by $U \approx (\hbar/2m)(y_0-\sqrt 2 \xi)^{-1}$, where $y_0$ is the distance from the center of the vortex to the wall, $\xi$ is the healing length of the condensate and $m$ is the mass of the boson.Comment: submitted to Phys Rev

Electrodynamics of Amorphous Media at Low Temperatures

Amorphous solids exhibit intrinsic, local structural transitions, that give rise to the well known quantum-mechanical two-level systems at low temperatures. We explain the microscopic origin of the electric dipole moment of these two-level systems: The dipole emerges as a result of polarization fluctuations between near degenerate local configurations, which have nearly frozen in at the glass transition. An estimate of the dipole's magnitude, based on the random first order transition theory, is obtained and is found to be consistent with experiment. The interaction between the dipoles is estimated and is shown to contribute significantly to the Gr\"{u}neisen parameter anomaly in low $T$ glasses. In completely amorphous media, the dipole moments are expected to be modest in size despite their collective origin. In partially crystalline materials, however, very large dipoles may arise, possibly explaining the findings of Bauer and Kador, J. Chem. Phys. {\bf 118}, 9069 (2003).Comment: Submitted for publication; April 27, 2005 versio

High-precision determination of the light-quark masses from realistic lattice QCD

Three-flavor lattice QCD simulations and two-loop perturbation theory are used to make the most precise determination to date of the strange-, up-, and down-quark masses, $m_s$, $m_u$, and $m_d$, respectively. Perturbative matching is required in order to connect the lattice-regularized bare- quark masses to the masses as defined in the \msbar scheme, and this is done here for the first time at next-to-next-to leading (or two-loop) order. The bare-quark masses required as input come from simulations by the MILC collaboration of a highly-efficient formalism (using so-called ``staggered'' quarks), with three flavors of light quarks in the Dirac sea; these simulations were previously analyzed in a joint study by the HPQCD and MILC collaborations, using degenerate $u$ and $d$ quarks, with masses as low as $m_s/8$, and two values of the lattice spacing, with chiral extrapolation/interpolation to the physical masses. With the new perturbation theory presented here, the resulting \msbar\ masses are m^\msbar_s(2 {GeV}) = 87(0)(4)(4)(0) MeV, and \hat m^\msbar(2 {GeV}) = 3.2(0)(2)(2)(0) MeV, where \hat m = \sfrac12 (m_u + m_d) is the average of the $u$ and $d$ masses. The respective uncertainties are from statistics, simulation systematics, perturbation theory, and electromagnetic/isospin effects. The perturbative errors are about a factor of two smaller than in an earlier study using only one-loop perturbation theory. Using a recent determination of the ratio $m_u/m_d = 0.43(0)(1)(0)(8)$ due to the MILC collaboration, these results also imply m^\msbar_u(2 {GeV}) = 1.9(0)(1)(1)(2) MeV and m^\msbar_d(2 {GeV}) = 4.4(0)(2)(2)(2) MeV. A technique for estimating the next order in the perturbative expansion is also presented, which uses input from simulations at more than one lattice spacing

European ectoparasitoids of two classical weed biological control agents released in North America

The ceutorhynchine weevils Hadroplontus litura (F.) and Microplontus edentulus (Schultze) (Coleoptera: Curculionidae), are established in North America as biological control agents for Canada thistle, Cirsium arvense (L.) Scop., and scentless chamomile, Tripleurospermum perforatum (Mérat) M. Lainz (Asteraceae), respectively. In North America, both weeds occur sympatrically and in similar habitats as another ceutorhynchine, Ceutorhynchus obstrictus (Marsham) (cabbage seedpod weevil), an important pest of canola, Brassica napus L., and Brassica rapa L. (Brassicaceae). Ceutorhynchinae weevils released to control weeds in cultivated crops may serve as alternate hosts if agents released for biological control of C. obstrictus are not specific to that species. Parasitoids associated with M. edentulus and H. litura inflict similar levels of mortality on their hosts, yet a single species was associated with the latter host, whereas 13 species attacked the former. The stem-mining M. edentulus appears to be at some risk but not the root-crown feeding H. litura, should the parasitoids Trichomalus perfectus (Walker) and Mesopolobus morys (Walker) (Hymenoptera: Pteromalidae) be introduced as biological control agents of the silique-feeding C. obstrictus. These findings suggest that feeding niche may be an important criterion for developing a nontarget species test list for host-range testing of potential biological control agent

Larval phenologies and parasitoids of two seed-feeding weevils associated with hoary cress and shepherd's purse (Brassicaceae) in Europe

In Europe, Ceutorhynchus turbatus Schultze and Ceutorhynchus typhae (Herbst) (Coleoptera: Curculionidae) feed on seeds from hoary cress and shepherd's purse (Cardaria draba (L.) Desv. and Capsella bursa-pastoris (L.) Medik.); both plants are invasive in North America. In North America, C. turbatus is a candidate for biological control of hoary cress, C. typhae is adventive, and both are sympatric with cabbage seedpod weevil (Ceutorhynchus obstrictus (Marsham)), an invasive alien pest of canola (Brassica napus L. and Brassica rapa L., Brassicaceae). We investigated host associations among C. turbatus, C. typhae, and their parasitoids in Europe. Of particular interest was host specificity of Trichomalus perfectus (Walker) and Mesopolobus morys (Walker) (Hymenoptera: Pteromalidae), candidates for biological control of C. obstrictus in North America. We found no evidence that T. perfectus attacks C. turbatus or C. typhae; however, M. morys was the most common parasitoid associated with C. turbatu

Review of the species of Trichomalus (Chalcidoidea: Pteromalidae) associated with Ceutorhynchus (Coleoptera: Curculionidae) host species of European origin

Six species of Trichomalus Thomson were reared as parasitoids of Ceutorhynchinae hosts in Europe during surveys in 2000-2004. Trichomalus rusticus (Walker) is treated as a valid species, resurrected from synonymy under T. lucidus (Walker), and T. lyttus (Walker) is transferred from synonymy under T. lucidus and newly placed in synonymy with T. rusticus. Illustrated keys to females and males are given to differentiate the six species (T. bracteatus (Walker), T. campestris (Walker), T. gynetelus (Walker), T. lucidus, T. perfectus (Walker), and T. rusticus) except for males of T. bracteatus and T. gynetelus. A lectotype female is designated for T. rusticus. Trichomalus campestris is newly recorded as a parasitoid of Ceutorhynchus cardariae Korotyaev. Implications of the host-parasitoid associations recovered by the surveys are discussed relative to introduction of species to North America for classical biological contro