Atomic position localization via dual measurement

We study localization of atomic position when a three-level atom interacts with a quantized standing-wave field in the Ramsey interferometer setup. Both the field quadrature amplitude and the atomic internal state are measured to obtain the atomic position information. It is found that this dual measurement scheme produces an interference pattern superimposed on a diffraction-like pattern in the atomic position distribution, where the former pattern originates from the state-selective measurement and the latter from the field measurement. The present scheme results in a better resolution in the position localization than the field-alone measurement schemes. We also discuss the measurement-correlated mechanical action of the standing-wave field on the atom in the light of Popper's test.Comment: 6.5 pages and 5 figure

Auxiliary particle theory of threshold singularities in photoemission and X-ray absorption spectra: Test of a conserving T-matrix approximation

We calculate the exponents of the threshold singularities in the photoemission spectrum of a deep core hole and its X-ray absorption spectrum in the framework of a systematic many-body theory of slave bosons and pseudofermions (for the empty and occupied core level). In this representation, photoemission and X-ray absorption can be understood on the same footing; no distinction between orthogonality catastrophe and excitonic effects is necessary. We apply the conserving slave particle T-matrix approximation (CTMA), recently developed to describe both Fermi and non-Fermi liquid behavior systems with strong local correlations, to the X-ray problem as a test case. The numerical results for both photoemission and X-ray absorption are found to be in agreement with the exact infrared powerlaw behavior in the weak as well as in the strong coupling regions. We point out a close relation of the CTMA with the parquet equation approach of Nozi{\`e}res et al.Comment: 10 pages, 9 figures, published versio

Spatially Averaged Quantum Inequalities Do Not Exist in Four-Dimensional Spacetime

We construct a particular class of quantum states for a massless, minimally coupled free scalar field which are of the form of a superposition of the vacuum and multi-mode two-particle states. These states can exhibit local negative energy densities. Furthermore, they can produce an arbitrarily large amount of negative energy in a given region of space at a fixed time. This class of states thus provides an explicit counterexample to the existence of a spatially averaged quantum inequality in four-dimensional spacetime.Comment: 13 pages, 1 figure, minor corrections and added comment

Soft x-ray spectroscopy experiments on the near K-edge of B in MB2 (M=Mg, Al, Ta, and Nb)

Soft X-ray absorption and emission measurements are performed for the K- edge of B in MB$_2$ (M=Mg, Al, Ta and Nb). Unique feature of MgB$_2$ with a high density of B 2$p_{xy}(\sigma)$-state below and above the Fermi edge, which extends to 1 eV above the edge, is confirmed. In contrast, the B 2$p$ density of states in AlB$_2$ and TaB$_2$, both of occupied and unoccupied states, decreased linearly towards the Fermi energy and showed a dip at the Fermi energy. Furthermore, there is a broadening of the peaks with $p\sigma$-character in XES and XAS of AlB$_2$, which is due to the increase of three dimensionality in the $p\sigma$-band in AlB$_2$. The DOS of NbB$_2$ has a dip just below the Fermi energy. The present results indicate that the large DOS of B-2$p\sigma$ states near the Fermi energy are crucial for the superconductivity of MgB$_2$.Comment: 3 pages text and 4 pages figures. accepted for publication to Phys. Rev.

Enhanced Joule Heating in Umbral Dots

We present a study of magnetic profiles of umbral dots (UDs) and its consequences on the Joule heating mechanisms. Hamedivafa (2003) studied Joule heating using vertical component of magnetic field. In this paper UDs magnetic profile has been investigated including the new azimuthal component of magnetic field which might explain the relatively larger enhancement of Joule heating causing more brightness near circumference of UD.Comment: 8 pages, 1 figure, accepted in Solar Physic

HPV-negative, but not HPV-positive, oropharyngeal carcinomas induce fibroblasts to support tumour invasion through micro-environmental release of HGF and IL-6.

Human papillomavirus (HPV) infection is causally related to a subset of oropharyngeal carcinomas (OPC) and is linked to a more favourable prognosis compared to HPV-negative OPC. The mechanisms underlying this effect on prognosis are not fully understood, but interactions with the tumour microenvironment may be pivotal. Here, we investigated the role of the tumour microenvironment in HPV-positive compared to HPV-negative cancer using 2D and 3D modelling of OPC interactions with stromal fibroblasts. HPV-negative, but not HPV-positive, OPC-derived cell lines induced a rapid fibroblast secretory response that supported 2D cancer cell migration and invasion in vitro. Array profiling of this HPV-negative induced fibroblast secretome identified hepatocyte growth factor (HGF) as the principal secreted factor that promoted cancer cell migration. The interaction between HPV-negative cell lines and fibroblasts in 2D was prevented using c-Met (HGF receptor) inhibitors, which further restricted both HPV-negative and positive cell invasion in 3D co-culture models. Furthermore, we discovered a synergistic relationship between HGF and IL-6 in the support of migration that relates JAK activation to HGF responsiveness in HPV-negative lines. In summary, our data show significant differences in the interactions between HPV-positive and HPV-negative OPC cells and stromal fibroblasts. In addition, we, provide in vitro evidence to support the clinical application of c-MET inhibitors in the control of early HPV-negative OPC

Projected sea surface temperatures over the 21st century: Changes in the mean, variability and extremes for large marine ecosystem regions of Northern Oceans

Global climate models were used to assess changes in the mean, variability and extreme sea surface temperatures (SSTs) in northern oceans with a focus on large marine ecosystems (LMEs) adjacent to North America, Europe, and the Arctic Ocean. Results were obtained from 26 models in the Community Model Intercomparison Project Phase 5 (CMIP5) archive and 30 simulations from the National Center for Atmospheric Research Large Ensemble Community Project (CESM-LENS). All of the simulations used the observed greenhouse gas concentrations for 1976–2005 and the RCP8.5 “business as usual” scenario for greenhouse gases through the remainder of the 21st century. In general, differences between models are substantially larger than among the simulations in the CESM-LENS, indicating that the SST changes are more strongly affected by model formulation than internal climate variability. The annual SST trends over 1976–2099 in the 18 LMEs examined here are all positive ranging from 0.05 to 0.5°C decade–1. SST changes by the end of the 21st century are primarily due to a positive shift in the mean with only modest changes in the variability in most LMEs, resulting in a substantial increase in warm extremes and decrease in cold extremes. The shift in the mean is so large that in many regions SSTs during 2070–2099 will always be warmer than the warmest year during 1976–2005. The SST trends are generally stronger in summer than in winter, as greenhouse gas heating is integrated over a much shallower climatological mixed layer depth in summer than in winter, which amplifies the seasonal cycle of SST over the 21st century. In the Arctic, the mean SST and its variability increases substantially during summer, when it is ice free, but not during winter when a thin layer of ice reforms and SSTs remain near the freezing point

The protection of rights and advancement of GenderS: in conversation with Abigail Nappier Cherup, Kevin D. Thomas, Wendy Hein, and Jack Coffin

In this panel discussion, we explore various ways that academics can advance work related to genderS, intersectionality and inequities so that it has impact within academia and in society. Panelists offer practical insights, relate challenges in doing this work, and suggest avenues for alternative yet impactful dissemination of work. The purpose is to demonstrate how those interested in supporting or working in this space might move from being allies to advocates and accomplices

Zero temperature string breaking in lattice quantum chromodynamics

The separation of a heavy quark and antiquark pair leads to the formation of a tube of flux, or "string", which should break in the presence of light quark-antiquark pairs. This expected zero-temperature phenomenon has proven elusive in simulations of lattice QCD. We study mixing between the string state and the two-meson decay channel in QCD with two flavors of dynamical sea quarks. We confirm that mixing is weak and find that it decreases at level crossing. While our study does not show direct effects of internal quark loops, our results, combined with unitarity, give clear confirmation of string breaking.Comment: 20 pages, 7 figures. With small clarifications and two additions to references. Submitted to Phys. Rev.

Comparison of Mass Wasting Processes on Vesta and Ceres

The Dawn mission has significantly enhanced our understanding regarding surface and subsurface geological processes on Vesta and Ceres. The ample amount of high resolution imaging and spectral data has improved our knowledge with respect to formation of small bodies, their evolution and current state [7, 12, 2, 17]. Earlier studies of mass movements on Vesta focus on the southern latitudes where the giant Rheasilvia impact basin is responsible for a high topographic relief representing ideal mass wasting conditions [8,9]. On Ceres, fluidized mass movement helped to assert the presence of water ice at shallow subsurface at global scale [15,3,6]. Using above finding as a base, we extend these studies by classifying [10] and comparing the mass movement behavior under similar gravity but compositionally different conditions present on Vesta and Ceres. Vesta being dry [7] and Ceres with water ice on shallow surface [17] may introduce differences within its landslide properties