Limits on Electron Neutrino Disappearance from the KARMEN and LSND electron neutrino - Carbon Cross Section Data

This paper presents a combined analysis of the KARMEN and LSND nu_e-carbon cross section measurements within the context of a search for nu_e disappearance at high Delta m^2. KARMEN and LSND were located at 17.7 m and 29.8 m respectively from the neutrino source, so the consistency of the two measurements, as a function of antineutrino energy, sets strong limits on neutrino oscillations. Most of the allowed region from the nu_e disappearance analysis of the Gallium calibration data is excluded at >95% CL and the best fit point is excluded at 3.6$\sigma$. Assuming CPT conservation, comparisons are also made to the oscillation analyses of reactor antineutrino data.Comment: Published versio

Curvature and torsion in growing actin networks

Intracellular pathogens such as Listeria monocytogenes and Rickettsia rickettsii move within a host cell by polymerizing a comet-tail of actin fibers that ultimately pushes the cell forward. This dense network of cross-linked actin polymers typically exhibits a striking curvature that causes bacteria to move in gently looping paths. Theoretically, tail curvature has been linked to details of motility by considering force and torque balances from a finite number of polymerizing filaments. Here we track beads coated with a prokaryotic activator of actin polymerization in three dimensions to directly quantify the curvature and torsion of bead motility paths. We find that bead paths are more likely to have low rather than high curvature at any given time. Furthermore, path curvature changes very slowly in time, with an autocorrelation decay time of 200 seconds. Paths with a small radius of curvature, therefore, remain so for an extended period resulting in loops when confined to two dimensions. When allowed to explore a 3D space, path loops are less evident. Finally, we quantify the torsion in the bead paths and show that beads do not exhibit a significant left- or right-handed bias to their motion in 3D. These results suggest that paths of actin-propelled objects may be attributed to slow changes in curvature rather than a fixed torque

The LSND and MiniBooNE Oscillation Searches at High Δm2\Delta m^2

This paper reviews the results of the LSND and MiniBooNE experiments. The primary goal of each experiment was to effect sensitive searches for neutrino oscillations in the mass region with $\Delta m^2 \sim 1$ eV$^2$. The two experiments are complementary, and so the comparison of results can bring additional information with respect to models with sterile neutrinos. Both experiments obtained evidence for $\bar \nu_\mu \rightarrow \bar \nu_e$ oscillations, and MiniBooNE also observed a $\nu_\mu \rightarrow \nu_e$ excess. In this paper, we review the design, analysis, and results from these experiments. We then consider the results within the global context of sterile neutrino oscillation models. The final data sets require a more extended model than the simple single sterile neutrino model imagined at the time that LSND drew to a close and MiniBooNE began. We show that there are apparent incompatibilities between data sets in models with two sterile neutrinos. However, these incompatibilities may be explained with variations within the systematic error. Overall, models with two (or three) sterile neutrinos seem to succeed in fitting the global data, and they make interesting predictions for future experiments.Comment: Posted with permission from the Annual Review of Nuclear and Particle Science, Volume 63. \c{opyright} 2013 by Annual Reviews, http://www.annualreviews.or

Temporal processing and context dependency in C. elegans mechanosensation

A quantitative understanding of how sensory signals are transformed into motor outputs places useful constraints on brain function and helps reveal the brain's underlying computations. We investigate how the nematode C. elegans responds to time-varying mechanosensory signals using a high-throughput optogenetic assay and automated behavior quantification. In the prevailing picture of the touch circuit, the animal's behavior is determined by which neurons are stimulated and by the stimulus amplitude. In contrast, we find that the behavioral response is tuned to temporal properties of mechanosensory signals, like its integral and derivative, that extend over many seconds. Mechanosensory signals, even in the same neurons, can be tailored to elicit different behavioral responses. Moreover, we find that the animal's response also depends on its behavioral context. Most dramatically, the animal ignores all tested mechanosensory stimuli during turns. Finally, we present a linear-nonlinear model that predicts the animal's behavioral response to stimulus.Comment: 40 pages, 8 main figures, 19 supplementary figure

Precision Measurement of sin^2 theta_W at a Reactor

This paper presents a strategy for measuring sin^2 theta_W to ~1% at a reactor-based experiment, using antineutrinos electron elastic scattering. This error is comparable to the NuTeV, SLAC E158, and APV results on sin^2 theta_W, but with substantially different contributions to the systematics. An improved method for identifying antineutrino proton events, which serve both as a background and as a normalization sample, is described. The measurement can be performed using the near detector of the presently proposed reactor-based oscillation experiments. We conclude that an absolute error of delta(sin^2 theta_W)=0.0019 may be achieved.Comment: To be Submitted to Phys. Rev.

Using Reactors to Measure θ13\theta_{13}

A next-generation neutrino oscillation experiment using reactor neutrinos could give important information on the size of mixing angle $\theta_{13}$. The motivation and goals for a new reactor measurement are discussed in the context of other measurements using off-axis accelerator neutrino beams. The reactor measurements give a clean measure of the mixing angle without ambiguities associated with the size of the other mixing angles, matter effects, and effects due to CP violation. The key question is whether a next-generation experiment can reach the needed sensitivity goals to make a measurement for $\sin^{2}2\theta_{13}$ at the 0.01 level. The limiting factors associated with a reactor disappearance measurement are described with some ideas of how sensitivities can be improved. Examples of possible experimental setups are presented and compared with respect to cost and sensitivity