Search for Leptonic Decays of Dark Photons at NA62.

The NA62 experiment at CERN, configured in beam-dump mode, has searched for dark photon decays in flight to electron-positron pairs using a sample of 1.4×10^{17} protons on dump collected in 2021. No evidence for a dark photon signal is observed. The combined result for dark photon searches in lepton-antilepton final states is presented and a region of the parameter space is excluded at 90% confidence level, improving on previous experimental limits for dark photon mass values between 50 and 600 MeV/c^{2} and coupling values in the range 10^{-6} to 4×10^{-5}. An interpretation of the e^{+}e^{-} search result in terms of the emission and decay of an axionlike particle is also presented.

How usefulness shapes neural representations during goal-directed behavior.

Value is often associated with reward, emphasizing its hedonic aspects. However, when circumstances change, value must also change (a compass outvalues gold, if you are lost). How are value representations in the brain reshaped under different behavioral goals? To answer this question, we devised a new task that decouples usefulness from its hedonic attributes, allowing us to study flexible goal-dependent mapping. Here, we show that, unlike sensory cortices, regions in the prefrontal cortex (PFC)-usually associated with value computation-remap their representation of perceptually identical items according to how useful the item has been to achieve a specific goal. Furthermore, we identify a coding scheme in the PFC that represents value regardless of the goal, thus supporting generalization across contexts. Our work questions the dominant view that equates value with reward, showing how a change in goals triggers a reorganization of the neural representation of value, enabling flexible behavior.

Relationship between zinc and obesity.

Zinc has important effects on metabolism, and on the thermoregulation of obese individuals. The aim of our investigation was to evaluate the serum zinc levels in obese patients before and after severe hypocaloric diets and to evaluate its correlation with the body mass index (BMI). Patients followed a severe hypocaloric diet (737 Kcal) for 60 days. Serum Zn levels and BMI were evaluated. Zn levels in obese patients were significantly (p < 0.01) lower than in controls, whereas the BMI values were significantly greater. At the end a severe hypocaloric diet, serum Zn and BMI levels returned to normal values. Our data show a possible relationship of the serum Zn levels with the anabolic and catabolic mechanisms in obesity, although the exact metabolic role of this bio-element remains unclear.