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Abstract According to the ‘selfish herd’ hypothesis, most seabird species breed colonially so that individuals can decrease their risk of predation by forming compact groups. However, costs and benefits associated with colonial breeding may not be evenly distributed among individuals within a colony. At Adélie penguin colonies, individuals nesting on the periphery of subcolonies (distinct groups of nests) may experience higher rates of nest predation by south polar skuas, and thus the optimal aggregation pattern for Adélie penguins may be within groups that minimize the proportion of edge nests. Nevertheless, some penguins choose to nest solitarily, at significant distances from conspecifics. We tracked 50 of these “solitary-nesting” Adélie penguins at Cape Crozier, a large colony on Ross Island, during the 2021 nesting season and compared their breeding success to individuals nesting within subcolony boundaries. We found that both solitary and subcolony nests successfully raised chicks large enough to join crèches and left unattended by adults. However, chicks from solitary nests exhibited a rate of mortality more than six times higher during the transition from nest brooding/guarding to crèche stage. In the 2022 nesting season, we found that solitary nests which had previously hosted actively breeding penguins were more likely to be re-occupied. Solitary nesting therefore appears to be a less-successful alternative to breeding within subcolonies, but enough individuals could be successful with this approach to maintain the apparently disadvantageous behavior and effectively pioneer previously unused locations, possibly including eventual new colony locations. 

Abstract We propose a new measurement of the ratio of positron-proton to electron-proton elastic scattering at DESY. The purpose is to determine the contributions beyond single-photon exchange, which are essential for the Quantum Electrodynamic (QED) description of the most fundamental process in hadronic physics. By utilizing a 20 cm long liquid hydrogen target in conjunction with the extracted beam from the DESY synchrotron, we can achieve an average luminosity of$$2.12\times 10^{35}$$ $2.12\times {10}^{35}$ cm$$^{-2}\cdot $$ ${}^{-2}·$s$$^{-1}$$ ${}^{-1}$ ($$\approx 200$$ $\approx 200$times the luminosity achieved by OLYMPUS). The proposed two-photon exchange experiment (TPEX) entails a commissioning run at a beam energy of 2 GeV, followed by measurements at 3 GeV, thereby providing new data up to$$Q^2=4.6$$ $Q^2=4.6$ (GeV/c)$$^2$$ ${}^2$(twice the range of current measurements). We present and discuss the proposed experimental setup, run plan, and expectations. 

In their Letter to Molecular Biology of the Cell, Schmoller et al. (2022) raise questions about the results and conclusions presented in our published studies (Dorsey et al., 2018; Litsios et al., 2019). Here, we respond to the criticisms of Schmoller et al. and demonstrate how wide-field fluorescence microscopy experiments to determine nuclear Whi5 concentration dynamics can be confounded by uncontrolled effects, which include photobleaching, partial confocal effects, and nuclear-to-cytoplasmic volume scaling. Further, we provide additional experimental evidence demonstrating that nuclear Whi5 concentration is essentially constant as cells grow in G1 phase and that Cln3 and protein synthesis dynamics occur as reported in Litsios et al. (2019). These results suggest that instead of being triggered by dilution of the stable inhibitor Whi5, Start is rather primarily controlled by the increase in protein synthesis rate in G1 and the concomitant production of the unstable activator Cln3. 

Measuring deeply virtual Compton scattering (DVCS) on the neutron is one of the necessary steps to understand the structure of the nucleon in terms of generalized parton distributions (GPDs). Neutron targets play a complementary role to transversely polarized proton targets in the determination of the GPD $E$. This poorly known and poorly constrained GPD is essential to obtain the contribution of the quarks’ angular momentum to the spin of the nucleon. DVCS on the neutron was measured for the first time selecting the exclusive final state by detecting the neutron, using the Jefferson Lab longitudinally polarized electron beam, with energies up to 10.6 GeV, and the CLAS12 detector. The extracted beam-spin asymmetries, combined with DVCS observables measured on the proton, allow a clean quark-flavor separation of the imaginary parts of the Compton form factors $\mathcal{H}$and $\mathcal{E}$. Published by the American Physical Society2024