Indirect Detection of Little Higgs Dark Matter

Little Higgs models with T parity contain an attractive dark matter candidate, the heavy photon. We compute the cross section of the heavy photon annihilation into Z-photon pairs, which turns out to be substantially higher than the previously computed cross section for the two photon final state. Unfortunately, even with this enhancement, the monochromatic photon flux from galactic heavy photon annihilation is unlikely to be detectable by GLAST or the currently operating atmospheric Cerenkov telescopes. We also compute the flux of high-energy neutrinos from the annihilation of the heavy photons captured by the Sun and the Earth. The maximum flux of upward-going muons due to such neutrinos is about 1 yr^{-1}km^{-2}.Comment: 13 pages, 3 figure

The exchange bias phenomenon in uncompensated interfaces: Theory and Monte Carlo simulations

We performed Monte Carlo simulations in a bilayer system composed by two thin films, one ferromagnetic (FM) and the other antiferromagnetic (AFM). Two lattice structures for the films were considered: simple cubic (sc) and a body center cubic (bcc). In both lattices structures we imposed an uncompensated interfacial spin structure, in particular we emulated a FeF2-FM system in the case of the (bcc) lattice. Our analysis focused on the incidence of the interfacial strength interactions between the films J_eb and the effect of thermal fluctuations on the bias field H_EB. We first performed Monte Carlo simulations on a microscopic model based on classical Heisenberg spin variables. To analyze the simulation results we also introduced a simplified model that assumes coherent rotation of spins located on the same layer parallel to the interface. We found that, depending on the AFM film anisotropy to exchange ratio, the bias field is either controlled by the intrinsic pinning of a domain wall parallel to the interface or by the stability of the first AFM layer (quasi domain wall) near the interface.Comment: 18 pages, 11 figure

A Framework to Evaluate the SDG Contribution of Fluvial Nature-Based Solutions

Nature-based solutions (NBSs) are measures reflecting the ‘cooperation with nature’ approach: mitigating fluvial flood risk while being cost-effective, resource-efficient, and providing numerous environmental, social, and economic benefits. Since 2015, the United Nations (UN) 2030 Agenda has provided UN member states with goals, targets, and indicators to facilitate an integrated approach focusing on economic, environmental, and social improvements simultaneously. The aim of this study is to evaluate the contribution of fluvial NBSs to the UN 2030 Agenda, using all its components: Sustainable Development Goals (SDGs), targets, and indicators. We propose a four-step framework with inputs from the UN 2030 Agenda, scientific literature, and case studies. The framework provides a set of fluvial flooding indicators that are linked to SDG indicators of the UN 2030 Agenda. Finally, the fluvial flooding indicators are tested by applying them to a case study, the Eddleston Water Project, aiming to examine its contribution to the UN 2030 Agenda. This reveals that the Eddleston Water Project contributes to 9 SDGs and 33 SDG targets from environmental, economic, societal, policy, and technical perspectives. Our framework aims to enhance the systematic considerations of the SDG indicators, adjust their notion to the system of interest, and thereby enhance the link between the sustainability performance of NBSs and the UN 2030 AgendaRivers, Ports, Waterways and Dredging Engineerin

North Atlantic evidence for a for a unipolar icehouse climate state at the Eocene-Oligocene Transition

This is the final version. Available from Wiley via the DOI in this record.Earth’s climate transitioned from a warm unglaciated state to a colder glaciated ‘icehouse’ state during the Cenozoic. Extensive ice sheets were first sustained on Antarctica at the Eocene-Oligocene Transition (EOT, ~34 Ma), but there is intense debate over whether Northern Hemisphere ice sheets developed simultaneously at this time, or tens of millions of years later. Here we report on EOT-age sediments that contain detrital sand from Integrated Ocean Drilling Program (IODP) Sites U1406 and U1411 on the Newfoundland margin. These sites are ideally located to test competing hypotheses of the extent of Arctic glaciation, being situated in the North Atlantic’s 'iceberg alley' where icebergs, calved from both the Greenland Ice Sheet today, and the Laurentide Ice Sheet during the Pleistocene, are concentrated by the Labrador Current and deposit continentally-derived detritus. Here we show that detrital sand grains present in these EOT-aged sediments from the Newfoundland margin, initially interpreted to represent ice rafting, were sourced from the mid-latitudes of North America. We find that these grains were transported to the western North Atlantic by fluvial and downslope processes, not icebergs, and were subsequently reworked and deposited by deep-water contour currents on the Newfoundland margin. Our findings are inconsistent with the presence of extensive ice sheets on southern and western Greenland, and the northeastern Canadian Arctic. This contradicts extensive bipolar glaciation at the EOT. The unipolar icehouse arose because of contrasting latitudinal continental configurations at the poles, requiring more intense Cenozoic climatic deterioration to trigger extensive Northern Hemisphere glaciation.Royal Societ

Mineralogy, petrology, and shock history of lunar meteorite Sayh al Uhaymir 300: A crystalline impact-melt breccia

Sayh al Uhaymir (SaU) 300 comprises a microcrystalline igneous matrix (grain size 10 m), dominated by plagioclase, pyroxene, and olivine. Pyroxene geothermometry indicates that the matrix crystallized at ~1100 degrees C. The matrix encloses mineral and lithic clasts that record the effects of variable levels of shock. Mineral clasts include plagioclase, low- and high-Ca pyroxene, pigeonite, and olivine. Minor amounts of ilmenite, FeNi metal, chromite, and a silica phase are also present. A variety of lithic clast types are observed, including glassy impact melts, impact-melt breccias, and metamorphosed impact melts. One clast of granulitic breccia was also noted. A lunar origin for SaU 300 is supported by the composition of the plagioclase (average An95), the high Cr content in olivine, the lack of hydrous phases, and the Fe/Mn ratio of mafic minerals. Both matrix and clasts have been locally overprinted by shock veins and melt pockets. SaU 300 has previously been described as an anorthositic regolith breccia with basaltic components and a granulitic matrix, but we here interpret it to be a polymict crystalline impact-melt breccia with an olivine-rich anorthositic norite bulk composition. The varying shock states of the mineral and lithic clasts suggest that they were shocked to between 5-28 GPa (shock stages S1-S2) by impact events in target rocks prior to their inclusion in the matrix. Formation of the igneous matrix requires a minimum shock pressure of 60 GPa (shock stage >S4). The association of maskelynite with melt pockets and shock veins indicates a subsequent, local 28-45 GPa (shock stage S2-S3) excursion, which was probably responsible for lofting the sample from the lunar surface. Subsequent fracturing is attributed to atmospheric entry and probable breakup of the parent meteor.The Meteoritics & Planetary Science archives are made available by the Meteoritical Society and the University of Arizona Libraries. Contact [email protected] for further information.Migrated from OJS platform February 202

Laboratory Focus on Improving the Culture of Biosafety: Statewide Risk Assessment of Clinical Laboratories That Process Specimens for Microbiologic Analysis

The Wisconsin State Laboratory of Hygiene challenged Wisconsin laboratories to examine their biosafety practices and improve their culture of biosafety. One hundred three clinical and public health laboratories completed a questionnaire-based, microbiology-focused biosafety risk assessment. Greater than 96% of the respondents performed activities related to specimen processing, direct microscopic examination, and rapid nonmolecular testing, while approximately 60% performed culture interpretation. Although they are important to the assessment of risk, data specific to patient occupation, symptoms, and travel history were often unavailable to the laboratory and, therefore, less contributory to a microbiology-focused biosafety risk assessment than information on the specimen source and test requisition. Over 88% of the respondents complied with more than three-quarters of the mitigation control measures listed in the survey. Facility assessment revealed that subsets of laboratories that claim biosafety level 1, 2, or 3 status did not possess all of the biosafety elements considered minimally standard for their respective classifications. Many laboratories reported being able to quickly correct the minor deficiencies identified. Task assessment identified deficiencies that trended higher within the general (not microbiology-specific) laboratory for core activities, such as packaging and shipping, direct microscopic examination, and culture modalities solely involving screens for organism growth. For traditional microbiology departments, opportunities for improvement in the cultivation and management of highly infectious agents, such as acid-fast bacilli and systemic fungi, were revealed. These results derived from a survey of a large cohort of small- and large-scale laboratories suggest the necessity for continued microbiology-based understanding of biosafety practices, vigilance toward biosafety, and enforcement of biosafety practices throughout the laboratory setting