Zircon U-Pb strain chronometry reveals deep impact-triggered flow

Large (>100km) meteorite impact cratering events play important roles in surface and biosphere evolution, however, their potential for widespread ductile modification of the lithosphere has been difficult to assess, due partly to our inability to isotopically age-correlate deep mineral fabrics with surface records. We have integrated benchmark U-Pb zircon dating methods (ID-TIMS, SHRIMP) with new microstructural techniques (EBSD, XRD) to demonstrate that crystal-plastic deformation can cause rapid out-diffusion of radiogenic Pb and accompanying trace element alteration in crystalline zircon. We have used this phenomenon to directly date fabric in Archean zircons and xenoliths of the lower crust of South Africa at 2023 15 million years, coeval with the 2020 3 million year old Vredefort cratering event at surface, with extent > or =20,000 km2. Our findings indicate that regional exogenic fabrics, similar to high-temperature tectonic fabrics, exist in ancient crust. Moreover, our results establish that crystal-plastic deformation in the lithosphere can now be directly dated and linked to planetary evolution by zircon U-Pb strain chronometry

The ‘caged torch procession’: Celebrities, protesters and the 2008 Olympic torch relay in London, Paris and San Francisco

Along with the opening and closing ceremonies, one of the major non-sports events associated with the modern Olympic Games is the torch relay. Although initiated in 1936, the relay has been subject to relatively little academic scrutiny. The events of April 2008 however will have cast a long shadow on the practice. This essay focuses primarily on one week (6–13 April) in the press coverage of the 2008 torch relay as the flame made its way from London to Paris in Europe and then to San Francisco in the USA. It discusses the interpretations offered in the mediated coverage about the relay, the Olympic movement, the host city and the locations where the relay was taking place, and critically analyses the role of agencies, both for and against the Olympics, that framed the ensuing debate

How do members of a fire and rescue service perceive expanding their roles to deliver more health care services?

Increasingly, public sector workers are being required to expand their roles into public health. Fire and rescue services, as part of the Emergency Medical Response trial, are at the forefront of role expansion, with increasing capacity due to reducing numbers of fires in recent years. Firefighter roles, successfully implemented, include responding to cardiac arrests and conducting checks on health and wellbeing in people's own homes. In this study, we explored fire service members' perceptions about this role expansion, to increase understanding of how role expansion can be introduced and supported.We interviewed 21 firefighters and team members about their perceptions of new roles. Interviews were conducted, transcribed and thematically analysed until reaching thematic saturation.Perspectives differed for responding to cardiac arrests and wellbeing checks. Cardiac arrests were seen as aligned with core roles and thus more acceptable. For both types of new role participants wanted more training and opportunities to provide feedback on implementation.How team members viewed role expansion depended on new role alignment with core role, training and being able to give feedback to management to shape future services

Systematic Definition of Protein Constituents along the Major Polarization Axis Reveals an Adaptive Reuse of the Polarization Machinery in Pheromone-Treated Budding Yeast

Polarizing cells extensively restructure cellular components in a spatially and temporally coupledmanner along the major axis of cellular extension. Budding yeast are a useful model of polarized growth, helping to define many molecular components of this conserved process. Besides budding, yeast cells also differentiate upon treatment with pheromone from the opposite mating type, forming a mating projection (the ‘shmoo’) by directional restructuring of the cytoskeleton, localized vesicular transport and overall reorganization of the cytosol. To characterize the proteomic localization changes ac-companying polarized growth, we developed and implemented a novel cell microarray-based imaging assay for measuring the spatial redistribution of a large fraction of the yeast proteome, and applied this assay to identify proteins localized along the mating projection following pheromone treatment. We further trained a machine learning algorithm to refine the cell imaging screen, identifying additional shmoo-localized proteins. In all, we identified 74 proteins that specifically localize to the mating projection, including previously uncharacterized proteins (Ycr043c, Ydr348c, Yer071c, Ymr295c, and Yor304c-a) and known polarization complexes such as the exocyst. Functional analysis of these proteins, coupled with quantitative analysis of individual organelle movements during shmoo formation, suggests a model in which the basic machinery for cell polarization is generally conserved between processe

A Compromise between Neutrino Masses and Collider Signatures in the Type-II Seesaw Model

A natural extension of the standard $SU(2)_{\rm L} \times U(1)_{\rm Y}$ gauge model to accommodate massive neutrinos is to introduce one Higgs triplet and three right-handed Majorana neutrinos, leading to a $6\times 6$ neutrino mass matrix which contains three $3\times 3$ sub-matrices $M_{\rm L}$, $M_{\rm D}$ and $M_{\rm R}$. We show that three light Majorana neutrinos (i.e., the mass eigenstates of $\nu_e$, $\nu_\mu$ and $\nu_\tau$) are exactly massless in this model, if and only if $M_{\rm L} = M_{\rm D} M_{\rm R}^{-1} M_{\rm D}^T$ exactly holds. This no-go theorem implies that small but non-vanishing neutrino masses may result from a significant but incomplete cancellation between $M_{\rm L}$ and $M_{\rm D} M_{\rm R}^{-1} M_{\rm D}^T$ terms in the Type-II seesaw formula, provided three right-handed Majorana neutrinos are of ${\cal O}(1)$ TeV and experimentally detectable at the LHC. We propose three simple Type-II seesaw scenarios with the $A_4 \times U(1)_{\rm X}$ flavor symmetry to interpret the observed neutrino mass spectrum and neutrino mixing pattern. Such a TeV-scale neutrino model can be tested in two complementary ways: (1) searching for possible collider signatures of lepton number violation induced by the right-handed Majorana neutrinos and doubly-charged Higgs particles; and (2) searching for possible consequences of unitarity violation of the $3\times 3$ neutrino mixing matrix in the future long-baseline neutrino oscillation experiments.Comment: RevTeX 19 pages, no figure

Role for zinc transporter gene SLC39A12 in the nervous system and beyond

The SLC39A12 gene encodes the zinc transporter protein ZIP12, which is expressed across many tissues and is highly abundant in the vertebrate nervous system. As a zinc transporter, ZIP12 functions to transport zinc across cellular membranes, including cellular zinc influx across the plasma membrane. Genome-wide association and exome sequencing studies have shown that brain susceptibility-weighted magnetic resonance imaging (MRI) intensity is associated with ZIP12 polymorphisms and rare mutations. ZIP12 is required for neural tube closure and embryonic development in Xenopus tropicalis. Frog embryos depleted of ZIP12 by antisense morpholinos develop an anterior neural tube defect and lack viability. ZIP12 is also necessary for neurite outgrowth and mitochondrial function in mouse neural cells. ZIP12 mRNA is increased in brain regions of schizophrenic patients. Outside of the nervous system, hypoxia induces ZIP12 expression in multiple mammalian species, including humans, which leads to endothelial and smooth muscle thickening in the lung and contributes towards pulmonary hypertension. Other studies have associated ZIP12 with other diseases such as cancer. Given that ZIP12 is highly expressed in the brain and that susceptibility-weighted MRI is associated with brain metal content, ZIP12 may affect neurological diseases and psychiatric illnesses such as Parkinson's disease, Alzheimer's disease, and schizophrenia. Furthermore, the induction of ZIP12 and resultant zinc uptake under pathophysiological conditions may be a critical component of disease pathology, such as in pulmonary hypertension. Drug compounds that bind metals like zinc may be able to treat diseases associated with impaired zinc homeostasis and altered ZIP12 function.Human Sciences Research and Graduate StudiesGraduate CollegeNutritional Science

Modeling gravimetric signatures of third-degree ocean tides and their detection in superconducting gravimeter records

We employ the barotropic, data-unconstrained ocean tide model TiME to derive an atlas for degree-3 tidal constituentsincluding monthly to terdiurnal tidal species. The model is optimized with respect to the tide gauge data set TICON-td that isextended to include the respective tidal constituents of diurnal and higher frequencies. The tide gauge validation shows a rootmean-square (RMS) deviation of 0.9–1.3mm for the individual species. We further model the load tide-induced gravimetric signals by two means (1) a global load Love number approach and (2) evaluating Greens-integrals at 16 selected locations of superconducting gravimeters. The RMS deviation between the amplitudes derived using both methods is below 0.5 nGal (1 nGal = 0.01 nm/s2 ) when excluding near-coastal gravimeters. Utilizing ETERNA-x, a recently upgraded and reworked tidal analysis software, we additionally derive degree-3 gravimetric tidal constituents for these stations, based on a hypothesis-free wave grouping approach.We demonstrate that this analysis is feasible, yielding amplitude predictions of only a few 10 nGal, and that it agrees with the modeled constituents on a level of 63–80% of the mean signal amplitude. Larger deviations are only found for lowest amplitude signals, near-coastal stations, or shorter and noisier data sets

Arrhythmogenic gene remodelling in elderly patients with type 2 diabetes with aortic stenosis and normal left ventricular ejection fraction

New Findings What is the central question of this study? Type 2 diabetes is associated with a higher rate of ventricular arrhythmias compared with the non‐diabetic population, but the associated myocardial gene expression changes are unknown; furthermore, it is also unknown whether any changes are attributable to chronic hyperglycaemia or are a consequence of structural changes. What is the main finding and its importance? We found downregulation of left ventricular ERG gene expression and increased NCX1 gene expression in humans with type 2 diabetes compared with control patients with comparable left ventricular hypertrophy and possible myocardial fibrosis. This was associated with QT interval prolongation. Diabetes and associated chronic hyperglycaemia may therefore promote ventricular arrhythmogenesis independently of structural changes. Type 2 diabetes is associated with a higher rate of ventricular arrhythmias, and this is hypothesized to be independent of coronary artery disease or hypertension. To investigate further, we compared changes in left ventricular myocardial gene expression in type 2 diabetes patients with patients in a control group with left ventricular hypertrophy. Nine control patients and seven patients with type 2 diabetes with aortic stenosis undergoing aortic valve replacement had standard ECGs, signal‐averaged ECGs and echocardiograms before surgery. During surgery, a left ventricular biopsy was taken, and mRNA expressions for genes relevant to the cardiac action potential were estimated by RT‐PCR. Mathematical modelling of the action potential and calcium transient was undertaken using the O'Hara–Rudy model using scaled changes in gene expression. Echocardiography revealed similar values for left ventricular size, filling pressures and ejection fraction between groups. No difference was seen in positive signal‐averaged ECGs between groups, but the standard ECG demonstrated a prolonged QT interval in the diabetes group. Gene expression of KCNH2 and KCNJ3 were lower in the diabetes group, whereas KCNJ2 , KCNJ5 and SLC8A1 expression were higher. Modelling suggested that these changes would lead to prolongation of the action potential duration with generation of early after‐depolarizations secondary to a reduction in density of the rapid delayed rectifier K+ current and increased Na+–Ca2+ exchange current. These data suggest that diabetes leads to pro‐arrythmogenic changes in myocardial gene expression independently of left ventricular hypertrophy or fibrosis in an elderly population

Three particles in an external trap: Nature of the complete J=0 spectrum

Three bosonic, spin-polarized atoms in a spherical oscillator potential constitutes the simplest nontrivial Bose-Einstein condensate (BEC). The present paper develops the tools needed to understand the nature of the complete J=0 energy spectrum for this prototype system, assuming a sum of two-body potentials. The resulting spectrum is calculated as a function of the two-body scattering length a_sc, which documents the evolution of certain many-body levels that evolve from BEC-type to molecular-type as the scattering length is decreased. Implications for the behavior of the condensate excited-state spectrum and for condensate formation and decay are elucidated. The energy levels evolve smoothly, even through the regime where the number of two-body bound states N_b increases by 1, and a_{sc} switches from -infinity to infinity. We point out the possibility of suppressing three-body recombination by tuning the two-body scattering length to values that are larger than the size of the condensate ground state. Comparisons with mean-field treatments are presented

An Experimental Investigation of Colonel Blotto Games

"This article examines behavior in the two-player, constant-sum Colonel Blotto game with asymmetric resources in which players maximize the expected number of battlefields won. The experimental results support all major theoretical predictions. In the auction treatment, where winning a battlefield is deterministic, disadvantaged players use a 'guerilla warfare' strategy which stochastically allocates zero resources to a subset of battlefields. Advantaged players employ a 'stochastic complete coverage' strategy, allocating random, but positive, resource levels across the battlefields. In the lottery treatment, where winning a battlefield is probabilistic, both players divide their resources equally across all battlefields." (author's abstract)"Dieser Artikel untersucht das Verhalten von Individuen in einem 'constant-sum Colonel Blotto'-Spiel zwischen zwei Spielern, bei dem die Spieler mit unterschiedlichen Ressourcen ausgestattet sind und die erwartete Anzahl gewonnener Schlachtfelder maximieren. Die experimentellen Ergebnisse bestätigen alle wichtigen theoretischen Vorhersagen. Im Durchgang, in dem wie in einer Auktion der Sieg in einem Schlachtfeld deterministisch ist, wenden die Spieler, die sich im Nachteil befinden, eine 'Guerillataktik' an, und verteilen ihre Ressourcen stochastisch auf eine Teilmenge der Schlachtfelder. Spieler mit einem Vorteil verwenden eine Strategie der 'stochastischen vollständigen Abdeckung', indem sie zufällig eine positive Ressourcenmenge auf allen Schlachtfeldern positionieren. Im Durchgang, in dem sich der Gewinn eines Schlachtfeldes probabilistisch wie in einer Lotterie bestimmt, teilen beide Spieler ihre Ressourcen gleichmäßig auf alle Schlachtfelder auf." (Autorenreferat