Compton Scattering and Photo-absorption Sum Rules on Nuclei

We revisit the photo-absorption sum rule for real Compton scattering from the proton and from nuclear targets. In analogy with the Thomas-Reiche-Kuhn sum rule appropriate at low energies, we propose a new "constituent quark model" sum rule that relates the integrated strength of hadronic resonances to the scattering amplitude on constituent quarks. We study the constituent quark model sum rule for several nuclear targets. In addition we extract the $\alpha=0$ pole contribution for both proton and nuclei. Using the modern high energy proton data we find that the $\alpha=0$ pole contribution differs significantly from the Thomson term, in contrast with the original findings by Damashek and Gilman.Comment: 8 pages, 4 figures, 2 tables; typos corrected; submitted to PR

Electroweak Constraints from Atomic Parity Violation and Neutrino Scattering

Precision electroweak physics can provide fertile ground for uncovering new physics beyond the Standard Model (SM). One area in which new physics can appear is in so-called "oblique corrections", i.e., next-to-leading order expansions of bosonic propagators corresponding to vacuum polarization. One may parametrize their effects in terms of quantities $S$ and $T$ that discriminate between conservation and non-conservation of isospin. This provides a means of comparing the relative contributions of precision electroweak experiments to constraints on new physics. Given the prevalence of strongly $T$-sensitive experiments, there is an acute need for further constraints on $S$, such as provided by atomic parity-violating experiments on heavy atoms. We evaluate constraints on $S$ arising from recently improved calculations in the Cs atom. We show that the top quark mass $m_t$ provides stringent constraints on $S$ within the context of the Standard Model. We also consider the potential contributions of next-generation neutrino scattering experiments to improved $(S,T)$ constraints.Comment: 10 pages, 4 figures, final corrected version to be published in Physical Review

Seismic reflection imaging of mixing processes in Fram Strait

The West Spitsbergen Current, which flows northward along the western Svalbard continental slope, transports warm and saline Atlantic water (AW) into the Arctic Ocean. A combined analysis of high-resolution seismic images and hydrographic sections across this current has uncovered the oceanographic processes involved in horizontal and vertical mixing of AW. At the shelf break, where a strong horizontal temperature gradient exists east of the warmest AW, isopycnal interleaving of warm AW and surrounding colder waters is observed. Strong seismic reflections characterize these interleaving features, with a negative polarity reflection arising from an interface of warm water overlying colder water. A seismic-derived sound speed image reveals the extent and lateral continuity of such interleaving layers. There is evidence of obliquely aligned internal waves emanating from the slope at 450–500 m. They follow the predicted trajectory of internal S2 tidal waves and can promote vertical mixing between Atlantic and Arctic-origin waters

Obstacles to integrated pest management adoption in developing countries

Despite its theoretical prominence and sound principles, integrated pest management (IPM) continues to suffer from anemic adoption rates in developing countries. To shed light on the reasons, we surveyed the opinions of a large and diverse pool of IPM professionals and practitioners from 96 countries by using structured concept mapping. The first phase of this method elicited 413 open-ended responses on perceived obstacles to IPM. Analysis of responses revealed 51 unique statements on obstacles, the most frequent of which was “insufficient training and technical support to farmers.” Cluster analyses, based on participant opinions, grouped these unique statements into six themes: research weaknesses, outreach weaknesses, IPM weaknesses, farmer weaknesses, pesticide industry interference, and weak adoption incentives. Subsequently, 163 participants rated the obstacles expressed in the 51 unique statements according to importance and remediation difficulty. Respondents from developing countries and high-income countries rated the obstacles differently. As a group, developing-country respondents rated “IPM requires collective action within a farming community” as their top obstacle to IPM adoption. Respondents from high-income countries prioritized instead the “shortage of well-qualified IPM experts and extensionists.” Differential prioritization was also evident among developing-country regions, and when obstacle statements were grouped into themes. Results highlighted the need to improve the participation of stakeholders from developing countries in the IPM adoption debate, and also to situate the debate within specific regional contexts

Atypical KRASG12R Mutant Is Impaired in PI3K Signaling and Macropinocytosis in Pancreatic Cancer

Allele-specific signaling by different KRAS alleles remains poorly understood. The KRASG12R mutation displays uneven prevalence among cancers that harbor the highest occurrence of KRAS mutations: It is rare (∼1%) in lung and colorectal cancers, yet relatively common (∼20%) in pancreatic ductal adenocarcinoma (PDAC), suggesting context-specific properties. We evaluated whether KRASG12R is functionally distinct from the more common KRASG12D- or KRASG12V-mutant proteins (KRASG12D/V). We found that KRASG12D/V but not KRASG12R drives macropinocytosis and that MYC is essential for macropinocytosis in KRASG12D/V- but not KRASG12R-mutant PDAC. Surprisingly, we found that KRASG12R is defective for interaction with a key effector, p110α PI3K (PI3Kα), due to structural perturbations in switch II. Instead, upregulated KRAS-independent PI3Kγ activity was able to support macropinocytosis in KRASG12R-mutant PDAC. Finally, we determined that KRASG12R-mutant PDAC displayed a distinct drug sensitivity profile compared with KRASG12D-mutant PDAC but is still responsive to the combined inhibition of ERK and autophagy. SIGNIFICANCE: We determined that KRASG12R is impaired in activating a key effector, p110α PI3K. As such, KRASG12R is impaired in driving macropinocytosis. However, overexpression of PI3Kγ in PDAC compensates for this deficiency, providing one basis for the prevalence of this otherwise rare KRAS mutant in pancreatic cancer but not other cancers.See related commentary by Falcomatà et al., p. 23.This article is highlighted in the In This Issue feature, p. 1

Human Herpes Virus 8 in HIV-1 infected individuals receiving cancer chemotherapy and stem cell transplantation

Background: Human Herpes Virus 8 (HHV8) can cause Kaposi’s Sarcoma (KS) in immunosuppressed individuals. However, little is known about the association between chemotherapy or hematopoietic stem cell transplantation (HSCT), circulating HHV8 DNA levels, and clinical KS in HIV-1-infected individuals with various malignancies. Therefore, we examined the associations between various malignancies, systemic cancer chemotherapy, T cell phenotypes, and circulating HHV8 DNA in 29 HIV-1-infected participants with concomitant KS or other cancer diagnoses. Methods: We quantified HHV8 plasma viral loads and cell-associated HHV8 DNA and determined the relationship between circulating HHV8 DNA and lymphocyte counts, and markers of early and late lymphocyte activation, proliferation and exhaustion. Results: There were no significant differences in plasma HHV8 DNA levels between baseline and post-chemotherapy time points or with the presence or absence of clinical KS. However, in two participants circulating HHV8 DNA increased following treatment for KS or HSCT for lymphoma,. We observed an approximately 2-log10 reduction in plasma HHV8 DNA in an individual with KS and multicentric Castleman disease following rituximab monotherapy. Although individuals with clinical KS had lower mean CD4+ T cell counts and percentages as expected, there were no significant associations with these factors and plasma HHV8 levels. We identified increased proportions of CD8+ and CD4+ T cells expressing CD69 (P = 0.01 & P = 0.04 respectively), and increased CD57 expression on CD4+ T cells (P = 0.003) in participants with detectable HHV8. Conclusion: These results suggest there is a complex relationship between circulating HHV8 DNA and tissue-based disease in HIV-1 and HHV8 co-infected individuals with various malignancies

COMAP Early Science: III. CO Data Processing

We describe the first season COMAP analysis pipeline that converts raw detector readouts to calibrated sky maps. This pipeline implements four main steps: gain calibration, filtering, data selection, and map-making. Absolute gain calibration relies on a combination of instrumental and astrophysical sources, while relative gain calibration exploits real-time total-power variations. High efficiency filtering is achieved through spectroscopic common-mode rejection within and across receivers, resulting in nearly uncorrelated white noise within single-frequency channels. Consequently, near-optimal but biased maps are produced by binning the filtered time stream into pixelized maps; the corresponding signal bias transfer function is estimated through simulations. Data selection is performed automatically through a series of goodness-of-fit statistics, including $\chi^2$ and multi-scale correlation tests. Applying this pipeline to the first-season COMAP data, we produce a dataset with very low levels of correlated noise. We find that one of our two scanning strategies (the Lissajous type) is sensitive to residual instrumental systematics. As a result, we no longer use this type of scan and exclude data taken this way from our Season 1 power spectrum estimates. We perform a careful analysis of our data processing and observing efficiencies and take account of planned improvements to estimate our future performance. Power spectrum results derived from the first-season COMAP maps are presented and discussed in companion papers.Comment: Paper 3 of 7 in series. 26 pages, 23 figures, submitted to Ap

COMAP Early Science: VI. A First Look at the COMAP Galactic Plane Survey

We present early results from the COMAP Galactic Plane Survey conducted between June 2019 and April 2021, spanning $20^\circ<\ell<40^\circ$ in Galactic longitude and |b|<1.\!\!^{\circ}5 in Galactic latitude with an angular resolution of $4.5^{\prime}$. The full survey will span $\ell \sim 20^{\circ}$- $220^{\circ}$ and will be the first large-scale radio continuum survey at $30$ GHz with sub-degree resolution. We present initial results from the first part of the survey, including diffuse emission and spectral energy distributions (SEDs) of HII regions and supernova remnants. Using low and high frequency surveys to constrain free-free and thermal dust emission contributions, we find evidence of excess flux density at $30\,$GHz in six regions that we interpret as anomalous microwave emission. Furthermore we model UCHII contributions using data from the $5\,$GHz CORNISH catalogue and reject this as the cause of the $30\,$GHz excess. Six known supernova remnants (SNR) are detected at $30\,$GHz, and we measure spectral indices consistent with the literature or show evidence of steepening. The flux density of the SNR W44 at $30\,$GHz is consistent with a power-law extrapolation from lower frequencies with no indication of spectral steepening in contrast with recent results from the Sardinia Radio Telescope. We also extract five hydrogen radio recombination lines to map the warm ionized gas, which can be used to estimate electron temperatures or to constrain continuum free-free emission. The full COMAP Galactic plane survey, to be released in 2023/2024, will be an invaluable resource for Galactic astrophysics.Comment: Paper 6 of 7 in series. 28 pages, 10 figures, submitted to Ap

COMAP Early Science: IV. Power Spectrum Methodology and Results

We present the power spectrum methodology used for the first-season COMAP analysis, and assess the quality of the current data set. The main results are derived through the Feed-feed Pseudo-Cross-Spectrum (FPXS) method, which is a robust estimator with respect to both noise modeling errors and experimental systematics. We use effective transfer functions to take into account the effects of instrumental beam smoothing and various filter operations applied during the low-level data processing. The power spectra estimated in this way have allowed us to identify a systematic error associated with one of our two scanning strategies, believed to be due to residual ground or atmospheric contamination. We omit these data from our analysis and no longer use this scanning technique for observations. We present the power spectra from our first season of observing and demonstrate that the uncertainties are integrating as expected for uncorrelated noise, with any residual systematics suppressed to a level below the noise. Using the FPXS method, and combining data on scales $k=0.051-0.62 \,\mathrm{Mpc}^{-1}$ we estimate $P_\mathrm{CO}(k) = -2.7 \pm 1.7 \times 10^4\mu\textrm{K}^2\mathrm{Mpc}^3$, the first direct 3D constraint on the clustering component of the CO(1-0) power spectrum in the literature.Comment: Paper 4 of 7 in series. 18 pages, 11 figures, as accepted in Ap