Metacarpophalangeal joint loads during bonobo locomotion: model predictions vs. proxies

The analysis of internal trabecular and cortical bone has been an informative tool for drawing inferences about behaviour in extant and fossil primate taxa. Within the hand, metacarpal bone architecture has been shown to correlate well with primate locomotion; however, the extent of morphological differences across taxa is unexpectedly small given the variability in hand use. One explanation for this observation is that the activity-related differences in the joint loads acting on the bone are simply smaller than estimated based on commonly used proxies (i.e. external loading and joint posture), which neglect the influence of muscle forces. In this study, experimental data and a musculoskeletal finger model are used to test this hypothesis by comparing differences between climbing and knuckle-walking locomotion of captive bonobos (Pan paniscus) based on (i) joint load magnitude and direction predicted by the models and (ii) proxy estimations. The results showed that the activity-related differences in predicted joint loads are indeed much smaller than the proxies would suggest, with joint load magnitudes being almost identical between the two locomotor modes. Differences in joint load directions were smaller but still evident, indicating that joint load directions might be a more robust indicator of variation in hand use than joint load magnitudes. Overall, this study emphasizes the importance of including muscular forces in the interpretation of skeletal remains and promotes the use of musculoskeletal models for correct functional interpretations

The position of Australopithecus sediba within fossil hominin hand use diversity

The human lineage is marked by a transition in hand use, from locomotion towards increasingly dexterous manipulation, concomitant with bipedalism. The forceful precision grips used by modern humans probably evolved in the context of tool manufacture and use, but when and how many times hominin hands became principally manipulative remains unresolved. We analyse metacarpal trabecular and cortical bone, which provide insight into behaviour during an individual’s life, to demonstrate previously unrecognized diversity in hominin hand use. The metacarpals of the palm in Australopithecus sediba have trabecular morphology most like orangutans and consistent with locomotor power-grasping with the fingers, while that of the thumb is consistent with human-like manipulation. This internal morphology is the first record of behaviour consistent with a hominin that used its hand for both arboreal locomotion and human-like manipulation. This hand use is distinct from other fossil hominins in this study, including A. afarensis and A. africanus

Constraints on Nucleon Decay via "Invisible" Modes from the Sudbury Neutrino Observatory

Data from the Sudbury Neutrino Observatory have been used to constrain the lifetime for nucleon decay to ``invisible'' modes, such as n -> 3 nu. The analysis was based on a search for gamma-rays from the de-excitation of the residual nucleus that would result from the disappearance of either a proton or neutron from O16. A limit of tau_inv > 2 x 10^{29} years is obtained at 90% confidence for either neutron or proton decay modes. This is about an order of magnitude more stringent than previous constraints on invisible proton decay modes and 400 times more stringent than similar neutron modes.Comment: Update includes missing efficiency factor (limits change by factor of 2) Submitted to Physical Review Letter

Impact of HO₂ aerosol uptake on radical levels and O₃ production during summertime in Beijing

The impact of heterogeneous uptake of HO2 on aerosol surfaces on radical concentrations and the O3 production regime in Beijing in summertime was investigated. The uptake coefficient of HO2 onto aerosol surfaces, , was calculated for the AIRPRO campaign in Beijing, in summer 2017, as a function of measured aerosol soluble copper concentration, [Cu2+]eff, aerosol liquid water content, [ALWC], and particulate matter concentration, [PM]. An average across the entire campaign of 0.070±0.035 was calculated, with values ranging from 0.002 to 0.15, and found to be significantly lower than the value of , commonly used in modelling studies. Using the calculated values for the summer AIRPRO campaign, OH, HO2 and RO2 radical concentrations were modelled using a box model incorporating the Master Chemical Mechanism (v3.3.1), with and without the addition of , and compared to the measured radical concentrations. The rate of destruction analysis showed the dominant HO2 loss pathway to be HO2 + NO for all NO concentrations across the summer Beijing campaign, with HO2 uptake contributing <0.3 % to the total loss of HO2 on average. This result for Beijing summertime would suggest that under most conditions encountered, HO2 uptake onto aerosol surfaces is not important to consider when investigating increasing O3 production with decreasing [PM] across the North China Plain. At low [NO], however, i.e. <0.1 ppb, which was often encountered in the afternoons, up to 29 % of modelled HO2 loss was due to HO2 uptake on aerosols when calculated was included, even with the much lower values compared to 0.2, a result which agrees with the aerosol-inhibited O3 regime recently proposed by Ivatt et al. (2022). As such it can be concluded that in cleaner environments, away from polluted urban centres where HO2 loss chemistry is not dominated by NO but where aerosol surface area is high still, changes in PM concentration and hence aerosol surface area could still have a significant effect on both overall HO2 concentration and the O3 production regime. Using modelled radical concentrations, the absolute O3 sensitivity to NOx and volatile organic compounds (VOCs) showed that, on average across the summer AIRPRO campaign, the O3 production regime remained VOC-limited, with the exception of a few days in the afternoon when the NO mixing ratio dropped low enough for the O3 regime to shift towards being NOx-limited. The O3 sensitivity to VOCs, the dominant regime during the summer AIRPRO campaign, was observed to decrease and shift towards a NOx-sensitive regime both when NO mixing ratio decreased and with the addition of aerosol uptake. This suggests that if [NOx] continues to decrease in the future, ozone reduction policies focussing solely on NOx reductions may not be as efficient as expected if [PM] and, hence, HO2 uptake to aerosol surfaces continue to decrease. The addition of aerosol uptake into the model, for both the calculated from measured data and when using a fixed value of , did not have a significant effect on the overall O3 production regime across the campaign. While not important for this campaign, aerosol uptake could be important for areas of lower NO concentration that are already in a NOx-sensitive regime

The first UK measurements of nitryl chloride using a chemical ionization mass spectrometer in central London in the summer of 2012, and an investigation of the role of Cl atom oxidation

The first nitryl chloride (ClNO2) measurements in the UK were made during the summer 2012 ClearfLo campaign with a chemical ionization mass spectrometer, utilizing an I− ionization scheme. Concentrations of ClNO2 exceeded detectable limits (11 ppt) every night with a maximum concentration of 724 ppt. A diurnal profile of ClNO2 peaking between 4 and 5 A.M., decreasing directly after sunrise, was observed. Concentrations of ClNO2 above the detection limit are generally observed between 8 P.M. and 11 A.M. Different ratios of the production of ClNO2:N2O5 were observed throughout with both positive and negative correlations between the two species being reported. The photolysis of ClNO2 and a box model utilizing the Master Chemical Mechanism modified to include chlorine chemistry was used to calculate Cl atom concentrations. Simultaneous measurements of hydroxyl radicals (OH) using low pressure laser‐induced fluorescence and ozone enabled the relative importance of the oxidation of three groups of measured VOCs (alkanes, alkenes, and alkynes) by OH radicals, Cl atoms, and O3 to be compared. For the day with the maximum calculated Cl atom concentration, Cl atoms in the early morning were the dominant oxidant for alkanes and, over the entire day, contributed 15%, 3%, and 26% toward the oxidation of alkanes, alkenes, and alkynes, respectively

Recent results from SNO

The SNO project has now completed two of its three major phases of operation. The no-oscillation hypothesis has been ruled out at 5σ in the pure heavy water phase and 8σ in the salt phase. Discussion in terms of the SeeSaw model is presented. © 2004 Published by Elsevier B.V

Neutral current and day night measurements from the pure D2O phase of SNO

The Sudbury Neutrino Observatory is a 1000 T D2O Cerenkov detector that is sensitive to B-8 solar neutrinos. The energy, radius, and direction with respect to the sun is Measured for each neutrino event; these distributions are used to separately determine the rates of the charged current, neutral current and electron scattering reactions of neutrinos on deuterium. Assuming an undistorted B-8 spectrum, the nu(e) component of the B-8 solar flux is phi(e) = 1.76(-0.05)(+0.05) (stat.)(-0.09)(+0.09) (syst.) X 10(6) cm(-2)s(-1) based on events with a measured kinetic energy above 5 MeV. The non-nu(e) component is phi(mutau) = 3.41(-0.45)(+0.45)(stat.)(-0.45)(+0.48) (syst.) X 10(6) cm(-2)s(-1), 5.3sigma greater than zero, providing strong evidence for solar nu(e) flavor transformation. The total flux measured with the NC reaction is phi(NC) = 5.09(-0.43)(+0.44) (stat.)(-0.43)(+0.46) (syst.) X 10(6) cm(-2)s(-1), consistent with solar models. The night minus day rate is 14.0% +/- 6.3%(+1.5)(-1.4)% of the average rate. If the total flux of active neutrinos is additionally constrained to have no asymmetry, the nu(e) asymmetry is found to be 7.0% +/- 4.9%(+1.3)(-1.2)%. A global solar neutrino analysis in terms of matter-enhanced oscillations of two active flavors strongly favors the Large Mixing Angle (LMA) solution

Search for Neutrinoless Double-β Decay in ^{76}Ge with the Majorana Demonstrator.

The Majorana Collaboration is operating an array of high purity Ge detectors to search for neutrinoless double-β decay in ^{76}Ge. The Majorana Demonstrator comprises 44.1&nbsp;kg of Ge detectors (29.7&nbsp;kg enriched in ^{76}Ge) split between two modules contained in a low background shield at the Sanford Underground Research Facility in Lead, South Dakota. Here we present results from data taken during construction, commissioning, and the start of full operations. We achieve unprecedented energy resolution of 2.5&nbsp;keV FWHM at Q_{ββ} and a very low background with no observed candidate events in 9.95&nbsp;kg yr of enriched Ge exposure, resulting in a lower limit on the half-life of 1.9×10^{25}  yr (90%&nbsp;C.L.). This result constrains the effective Majorana neutrino mass to below 240-520&nbsp;meV, depending on the matrix elements used. In our experimental configuration with the lowest background, the background is 4.0_{-2.5}^{+3.1}  counts/(FWHM t yr)