Repeating head-on collisions in an optical trap and the evaluation of spin-dependent interactions among neutral particles

A dynamic process of repeating collisions of a pair of trapped neutral particles with weak spin-dependent interaction is designed and studied. Related theoretical derivation and numerical calculation have been performed to study the inherent coordinate-spin and momentum-spin correlation. Due to the repeating collisions the effect of the weak interaction can be accumulated and enlarged, and therefore can be eventually detected. Numerical results suggest that the Cr-Cr interaction, which has not yet been completely clear, could be thereby determined. The design can be in general used to determine various interactions among neutral atoms and molecules, in particular for the determination of very weak forces.Comment: 15 pages, 7 figure

SU(3) Clebsch-Gordan Coefficients for Baryon-Meson Coupling at Arbitrary N_c

We present explicit formulae for the SU(3) Clebsch-Gordan coefficients that are relevant for the couplings of large N_c baryons to mesons. In particular, we compute the Clebsch-Gordan series for the coupling of the octet (associated with mesons, and remains the correct representation at large N_c) to the large N_c analogs of the baryon octet and decuplet representations.Comment: 8 pages, no figures, ReVTe

Linear Programming in the Semi-streaming Model with Application to the Maximum Matching Problem

In this paper, we study linear programming based approaches to the maximum matching problem in the semi-streaming model. The semi-streaming model has gained attention as a model for processing massive graphs as the importance of such graphs has increased. This is a model where edges are streamed-in in an adversarial order and we are allowed a space proportional to the number of vertices in a graph. In recent years, there has been several new results in this semi-streaming model. However broad techniques such as linear programming have not been adapted to this model. We present several techniques to adapt and optimize linear programming based approaches in the semi-streaming model with an application to the maximum matching problem. As a consequence, we improve (almost) all previous results on this problem, and also prove new results on interesting variants

High fluxes of deep volatiles from ocean island volcanoes: Insights from El Hierro, Canary Islands

Basaltic volcanism contributes significant fluxes of volatiles (CO2, H2O, S, F, Cl) to the Earth’s surface environment. Quantifying volatile fluxes requires initial melt volatile concentrations to be determined, which can be accessed through crystal-hosted melt inclusions. However, melt inclusions in volatile-rich mafic alkaline basalts, such as those erupted at ocean islands, often trap partially degassed melts, meaning that magmatic volatile fluxes from these tectonic settings are often significantly underestimated. We have measured major, trace element and volatile concentrations in melt inclusions from a series of young (<20 ka) basanites from El Hierro, Canary Islands. Our melt inclusions show some of the highest CO2 (up to 3600 ppm) and S (up to 4290 ppm) concentrations measured in ocean island basalts to date, in agreement with data from the recent 2011-2012 eruption. Volatile enrichment is observed in melt inclusions with crystallisation-controlled major element compositions and highly variable trace element ratios such as La/Yb. We use volatile-trace element ratios to calculate original magmatic CO2 contents up to 4.2 wt%, which indicates at least 65% of the original CO2 was degassed prior to melt inclusion trapping. The trace element contents and ratios of El Hierro magmas are best reproduced by 1-8% partial melting of a garnet lherzolite mantle source. Our projected CO2 (200-680 ppm) and S (265-450 ppm) concentrations for the source are consistent with upper estimates for primitive mantle. However, El Hierro magmas have elevated F/Nd and F/Cl in comparison with melts from a primitive mantle, indicating that the mantle must also contain a component enriched in F and other volatiles, most probably recycled oceanic lithosphere. Our modelled original magmatic CO2 contents indicates that, per mass unit, volatile fluxes from El Hierro magmas are up to two orders of magnitude greater than from typical mid-ocean ridge basalts and 1.5 to 7 times greater than from recent Icelandic eruptions, indicating large variability in the primary volatile content of magmas formed in di fferent geodynamic settings, or even within di fferent ocean islands. Our results highlight the importance of characterising mantle heterogeneity in order to accurately constrain both short- and long-term magmatic volatile emissions and fluxes from ocean island volcanoes.NERC studentship NE/L002469/1 NERC grant 526 IMF600/101

Tuning Interfacial Spins in Antiferromagnetic–Ferromagnetic–Heavy-Metal Heterostructures via Spin-Orbit Torque

Antiferromagnets are outstanding candidates for the next generation of spintronic applications, with great potential for downscaling and decreasing power consumption. Recently, the manipulation of bulk properties of antiferromagnets has been realized by several different approaches. However, the interfacial spin order of antiferromagnets is an important integral part of spintronic devices, and thus, the successful control of interfacial antiferromagnetic spins is urgently desired. Here, we report the high controllability of interfacial spins in antiferromagnetic–ferromagnetic–heavy-metal heterostructure devices using spin-orbit torque (SOT) assisted by perpendicular or longitudinal magnetic fields. Switching of the interfacial spins from one direction to another through multiple intermediate states is demonstrated. The field-free SOT-induced reorientation of antiferromagnetic interfacial spins is also observed, which we attribute to the effective built-in out-of-plane field due to unequal upward and downward interfacial spin populations. Our work provides a precise way to modulate the interfacial spins at an antiferromagnet/ferromagnet interface via SOT, which will greatly promote innovative designs for next-generation spintronic devices

Interplay of static and dynamic effects in 6He+ 238U Fusion

We investigate the influence of the neutron halo and the breakup channel in 6He + 238U fusion at near-barrier energies. To include static effects of the 2n-halo in 6He nuclei, we use a single-folding potential obtained from an appropriate nucleon-238U interaction and a realistic 6He density. Dynamical effects arising from the breakup process are then included through coupled-channel calculations. These calculations suggest that static effects dominate the cross section at energies above the Coulomb barrier, while the sub-barrier fusion cross section appears to be determined by coupling to the breakup channel. This last conclusion is uncertain due to the procedure employed to measure the fusion cross-section.Comment: 13 pages, 4 figure

A multilingual key to the genera and subgenera of the subfamily Scarabaeinae of the New World (Coleoptera: Scarabaeidae)

Presented is a multilingual (English, Portuguese, Spanish, Dutch and French) key to the 119 currently recognized genera and subgenera of scarabaeine dung beetles (Coleoptera: Scarabaeidae: Scarabaeinae) occurring in the New World. Also included are illustrations of representative species of all taxa included in the key as well as supplementary references to studies at the species level.Fil: Vaz de Mello, Fernando Z.. Universidade Federal de Mato Grosso; BrasilFil: Edmonds, W. D.. No especifica;Fil: Ocampo, Federico Carlos. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Mendoza. Instituto Argentino de Investigaciones de las Zonas Áridas. Provincia de Mendoza. Instituto Argentino de Investigaciones de las Zonas Áridas. Universidad Nacional de Cuyo. Instituto Argentino de Investigaciones de las Zonas Áridas; ArgentinaFil: Schoolmeesters, Paul. No especifica

The executive control of face memory

Abstract. Patients with frontal lobe damage and cognitively normal elderly individuals demonstrate increased susceptibility to false facial recognition. In this paper we review neuropsychological evidence consistent with the notion that the common functional impairment underlying face memory distortions in both subject populations is a context recollection/source monitoring deficit, coupled with excessive reliance on relatively preserved facial familiarity signals in recognition decisions. In particular, we suggest that due to the breakdown of strategic memory retrieval, monitoring, and decision operations, individuals with frontal lobe impairment caused by focal damage or age-related functional decline do not have a reliable mechanism for attributing the experience of familiarity to the correct context or source. Memory illusions are mostly apparent under conditions of uncertainty when the face cue does not directly elicit relevant identity-specific contextual information, leaving the source of familiarity unspecified or ambiguous. Based on these findings, we propose that remembering faces is a constructive process that requires dynamic interactions between temporal lobe memory systems that operate in an automatic or bottom-up fashion and frontal executive systems that provide strategic top-down control of recollection. Executive memory control functions implemented by prefrontal cortex play a critical role in suppressing false facial recognition and related source memory misattributions

To sink, swim, twin, or nucleate: A critical appraisal of crystal aggregation processes

Abstract Crystal aggregates in igneous rocks have been variously ascribed to growth processes (e.g., twinning, heterogeneous nucleation, epitaxial growth, dendritic growth), or dynamical processes (e.g., synneusis, accumulation during settling). We tested these hypotheses by quantifying the relative orientation of adjacent crystals using electron backscatter diffraction. Both olivine aggregates from Kīlauea volcano (Hawaiʻi, USA) and chromite aggregates from the Bushveld Complex (South Africa) show diverse attachment geometries inconsistent with growth processes. Near-random attachments in chromite aggregates are consistent with accumulation by settling of individual crystals. Attachment geometries and prominent geochemical differences across grain boundaries in olivine aggregates are indicative of synneusis.</jats:p