How can we test seesaw experimentally?

The seesaw mechanism for the small neutrino mass has been a popular paradigm, yet it has been believed that there is no way to test it experimentally. We present a conceivable outcome from future experiments that would convince us of the seesaw mechanism. It would involve a variety of data from LHC, ILC, cosmology, underground, and low-energy flavor violation experiments to establish the case.Comment: 5 pages, 4 figure

Obstacle crossing during locomotion: Visual exproprioceptive information is used in an online mode to update foot placement before the obstacle but not swing trajectory over it

YesAlthough gaze during adaptive gait involving obstacle crossing is typically directed two or more steps ahead, visual information of the swinging lower-limb and its relative position in the environment (termed visual exproprioception) is available in the lower visual field (lvf). This study determined exactly when lvf exproprioceptive information is utilised to control/update lead-limb swing trajectory during obstacle negotiation. 12 young participants negotiated an obstacle wearing smart-glass goggles which unpredictably occluded the lvf for certain periods during obstacle approach and crossing. Trials were also completed with lvf occluded for the entirety of the trial. When lvf was occluded throughout, footplacement distance and toe-clearance became significantly increased; which is consistent with previous work that likewise used continuous lvf occlusion. Both variables were similarly affected by lvf occlusion from instant of penultimate-step contact, but both were unaffected when lvf was occluded from instant of final-step contact. These findings suggest that lvf (exproprioceptive) input is typically used in an online manner to control/update final foot-placement, and that without such control, uncertainty regarding foot placement causes toe-clearance to be increased. Also that lvf input is not normally exploited in an online manner to update toe-clearance during crossing: which is contrary to what previous research has suggested

FDIONIC18 Interactions and stabilisation of acetone, sulfur dioxide and water with 1-octyl-3-methylimidazolium tetrafluoroborate at low temperatures

The interactions between three small molecules, water (H2O) , sulfur dioxide (SO2) and acetone ( (CH3)2CO ) with the ionic liquid (IL) 1-octyl-3-methylimidazolium tetrafluoroborate, [OMIM][BF4], have been determined using line of sight temperature programmed desorption (LOSTPD) from a gold surface. Multilayers of the IL were deposited by physical vapour deposition with multilayers of the small molecular species (adsorbed from the gas phase) at 90 K. LOSTPD was then carried out with the small molecular species desorbing first from the mixed multilayer, followed at higher temperatures by desorption of the IL from the gold surface. The IL had a high activation energy for desorption of 126(6) kJ mol-1 . Pure acetone showed a desorption activation energy of 38(2) kJ mol-1, which increased to 45 - 61 kJ mol-1 when it was pre-adsorbed below an overlying porous layer of the ionic liquid at 90 K. The stabilised acetone is thought to be associated with pores containing ionic moieties. Destabilised acetone was also observed and thought to originate from pores containing octyl chains. The quantity of stabilised acetone scaled with the amount of IL, being ≈ 1.1 molecules per IL ion pair. SO2 and H2O were co-adsorbed with the IL at 90 K leading to an intimate mixture of the two. For pure SO2 the desorption energy was 32(2) kJ mol-1, which increased to 40 - 50 kJ mol-1 for relative concentrations up to 6 SO2 molecules per IL ion pair. For pure water the activation energies were 49(5) kJ mol-1 and 43(1) kJ mol-1 for amorphous and crystalline ice respectively. When co-adsorbed with the IL the stabilisation energies were 42 - 49 kJ mol-1, but up to 505 water molecules per IL ion pair could be stabilised to some degree. The desorption mechanisms and the reasons for these interactions are discussed

Mechanisms of shape-based spatial learning

The ability to navigate to important locations is fundamental to both human and non-human animals. The experiments presented in this thesis were designed to address three key predictions generated from the model of navigation proposed by Miller and Shettleworth (2007, 2008, 2013): First, cue competition effects should be observed between local geometric information and landmarks; Second, the attention paid to geometric and non-geometric cues within an environment should not be modifiable; Third, organisms should not learn about a global representation of the shape of the environment. The results of the blocking experiments reported in Chapter 2 demonstrate that local geometric cues compete with non-geometric cues for control over navigational behaviour, in a manner consistent with the Miller-Shettleworth model. The intradimensional-extradimensional shift and learned predictiveness effects reported in Chapters 3 and 4, respectively, are not consistent with the notion that the attention paid to geometric and non-geometric cues is fixed. The experiments reported in Chapter 5 provide core evidence that humans encode a global representation of the shape of the environments in which they navigate, a result that is also not consistent with the Miller-Shettleworth model. These results suggest that, at best, the model proposed by Miller and Shettleworth (2007, 2008, 2013) provides an incomplete explanation for spatial learning behaviour. In order to account for the data reported in Chapters 3 and 4, it is necessary for the Miller-Shettleworth model to permit changes in the attention paid to navigational stimuli. Additionally, in order to account for the data presented in Chapter 5, it appears necessary to assume that humans encode a global Euclidean representation of the shape of the environments in which they navigate. The challenge for future work will be to determine the precise manner in which multiple representations of environmental geometry support effective navigation

Mechanisms of shape-based spatial learning

The ability to navigate to important locations is fundamental to both human and non-human animals. The experiments presented in this thesis were designed to address three key predictions generated from the model of navigation proposed by Miller and Shettleworth (2007, 2008, 2013): First, cue competition effects should be observed between local geometric information and landmarks; Second, the attention paid to geometric and non-geometric cues within an environment should not be modifiable; Third, organisms should not learn about a global representation of the shape of the environment. The results of the blocking experiments reported in Chapter 2 demonstrate that local geometric cues compete with non-geometric cues for control over navigational behaviour, in a manner consistent with the Miller-Shettleworth model. The intradimensional-extradimensional shift and learned predictiveness effects reported in Chapters 3 and 4, respectively, are not consistent with the notion that the attention paid to geometric and non-geometric cues is fixed. The experiments reported in Chapter 5 provide core evidence that humans encode a global representation of the shape of the environments in which they navigate, a result that is also not consistent with the Miller-Shettleworth model. These results suggest that, at best, the model proposed by Miller and Shettleworth (2007, 2008, 2013) provides an incomplete explanation for spatial learning behaviour. In order to account for the data reported in Chapters 3 and 4, it is necessary for the Miller-Shettleworth model to permit changes in the attention paid to navigational stimuli. Additionally, in order to account for the data presented in Chapter 5, it appears necessary to assume that humans encode a global Euclidean representation of the shape of the environments in which they navigate. The challenge for future work will be to determine the precise manner in which multiple representations of environmental geometry support effective navigation

Quark mass uncertainties revive KSVZ axion dark matter

The Kaplan-Manohar ambiguity in light quark masses allows for a larger uncertainty in the ratio of up to down quark masses than naive estimates from the chiral Lagrangian would indicate. We show that it allows for a relaxation of experimental bounds on the QCD axion, specifically KSVZ axions in the $2-3 \mu$eV mass range composing 100% of the galactic dark matter halo can evade the experimental limits placed by the ADMX collaboration.Comment: 9 pages, 5 figure

Individual differences in theta-band oscillations in a spatial memory network revealed by electroencephalography predict rapid place learning

Spatial memory has been closely related to the medial temporal lobe (MTL) and theta-oscillations are thought to play a key role. However, it remains difficult to investigate MTL activation related to spatial memory with non-invasive electrophysiological methods in humans. Here, we combined the virtual delayed-matching-to-place (DMP) task, reverse-translated from the watermaze DMP task in rats, with high-density electroencephalography (EEG) recordings. Healthy young volunteers performed this computerised task in a virtual circular arena, which contained a hidden target whose location moved to a new place every four trials, allowing the assessment of rapid memory formation. Using behavioural measures as predictor variables for source reconstructed frequency specific EEG power, we found that inter-individual differences in ‘search preference’ during ‘probe trials’, a measure of 1-trial place learning known from rodent studies to be particularly hippocampus dependent, correlated predominantly with distinct theta-band oscillations (approx. 7 Hz), particularly in the right temporal lobe, the right striatum and inferior occipital cortex or cerebellum. This pattern was found during both encoding and retrieval/expression, but not in control analyses and could not be explained by motor confounds. Alpha-activity in sensorimotor and parietal cortex contralateral to the hand used for navigation also correlated (inversely) with search preference. This latter finding likely reflects movement-related factors associated with task performance, as well as a frequency difference in (ongoing) alpha-rhythm for high-performers vs low-performers that may contribute to these results indirectly. Relating inter-individual differences in ongoing brain activity to behaviour in a continuous rapid place learning task that is suitable for a variety of populations, we could demonstrate that memory related theta-band activity in temporal lobe can be measured with EEG recordings. This approach holds great potential for further studies investigating the interactions within this network during encoding and retrieval, as well as neuromodulatory impacts and age-related changes

Thin film structural analysis using variable-period x-ray standing waves

Variable-period x-ray standing wave (VPXSW) studies have been carried out using 3 keV x rays and photoelectron detection. Two model surfaces have been used, a native SiO2 layer (20 Å thick) on bulk silicon, and a purpose-built multilayer surface comprising a chloroform/water marker layer (12 Å thick) on an ionic liquid spacer layer (211 Å thick) deposited on a SiO2/Si substrate at 90 K. By using photoelectron detection, both chemical and elemental sensitivity were achieved. The surfaces were modeled using dynamic x-ray scattering for x-ray intensity, and attenuation of photoelectrons transmitted through the layers, to produce simulations which accurately reproduced the experimental VPXSW measurements. VPXSW measurements made using the substrate, spacer layer, and marker layer photoelectron signatures produced consistent structural values. This work demonstrates that VPXSW can be used to determine chemically specific layer thicknesses within thick (≲300Å) surface structures composed of the light elements B, C, N, O, F, and Cl with an accuracy of 10 to 15 Å, perpendicular to the surface

Genome-wide association study of Stayability and Heifer Pregnancy in Red Angus cattle

Reproductive performance is the most important component of cattle production from the standpoint of economic sustainability of commercial beef enterprises. Heifer Pregnancy (HPG) and Stayability (STAY) genetic predictions are 2 selection tools published by the Red Angus Association of America (RAAA) to assist with improvements in reproductive performance. Given the importance of HPG and STAY to the profitability of commercial beef enterprises, the objective of this study was to identify QTL associated with both HPG and STAY in Red Angus cattle. A genome-wide association study (GWAS) was performed using deregressed HPG and STAY EBV, calculated using a single-trait animal model and a 3-generation pedigree with data from the Spring 2015 RAAA National Cattle Evaluation. Each individual animal possessed 74,659 SNP genotypes. Individual animals with a deregressed EBV reliability \u3e 0.05 were merged with the genotype file and marker quality control was performed. Criteria for sifting genotypes consisted of removing those markers where any of the following were found: average call rate less than 0.85, minor allele frequency \u3c 0.01, lack of Hardy–Weinberg equilibrium (P \u3c 0.0001), or extreme linkage disequilibrium (r2 \u3e 0.99). These criteria resulted in 2,664 animals with 62,807 SNP available for GWAS. Association studies were performed using a Bayes Cπ model in the BOLT software package. Marker significance was calculated as the posterior probability of inclusion (PPI), or the number of instances a specific marker was sampled divided by the total number of samples retained from the Markov chain Monte Carlo chains. Nine markers, with a PPI ≥ 3% were identified as QTL associated with HPG on BTA 1, 11, 13, 23, and 29. Twelve markers, with a PPI ≥ 75% were identified as QTL associated with STAY on BTA 6, 8, 9, 12, 15, 18, 22, and 23