Velocity dependent interactions and a new sum rule in bcc He

Recent neutron scattering experiments [PRL,{\bf 88},p.195301 (2002)] on solid $^4$He, discovered a new optic-like mode in the bcc phase. This excitation was predicted by a recently proposed model that describes the correlated atomic zero-point motion in bcc Helium in terms of dynamic electric dipole moments. Modulations of the relative phase of these dipoles between different atoms describes the anomalously soft T$_1$(110) phonon and two new optic-like modes, one of which was recently found in the neutron scattering experiments. In this work we show that the correlated dipolar interactions can be written as a velocity dependent interaction. This then results in a modified f-sum rule for the T$_1$(110) phonon, in good agreement with the recent experimental data.Comment: 5 pages, 3 figure

Periodicities in the Daily Proton Fluxes from 2011 to 2019 Measured by the Alpha Magnetic Spectrometer on the International Space Station from 1 to 100 GV

We present the precision measurement of the daily proton fluxes in cosmic rays from May 20, 2011 to October 29, 2019 (a total of 2824 days or 114 Bartels rotations) in the rigidity interval from 1 to 100 GV based on 5.5×109 protons collected with the Alpha Magnetic Spectrometer aboard the International Space Station. The proton fluxes exhibit variations on multiple timescales. From 2014 to 2018, we observed recurrent flux variations with a period of 27 days. Shorter periods of 9 days and 13.5 days are observed in 2016. The strength of all three periodicities changes with time and rigidity. The rigidity dependence of the 27-day periodicity is different from the rigidity dependences of 9-day and 13.5-day periods. Unexpectedly, the strength of 9-day and 13.5-day periodicities increases with increasing rigidities up to ∼10 GV and ∼20 GV, respectively. Then the strength of the periodicities decreases with increasing rigidity up to 100 GV.</p

Reducing the environmental impact of surgery on a global scale: systematic review and co-prioritization with healthcare workers in 132 countries

Background Healthcare cannot achieve net-zero carbon without addressing operating theatres. The aim of this study was to prioritize feasible interventions to reduce the environmental impact of operating theatres. Methods This study adopted a four-phase Delphi consensus co-prioritization methodology. In phase 1, a systematic review of published interventions and global consultation of perioperative healthcare professionals were used to longlist interventions. In phase 2, iterative thematic analysis consolidated comparable interventions into a shortlist. In phase 3, the shortlist was co-prioritized based on patient and clinician views on acceptability, feasibility, and safety. In phase 4, ranked lists of interventions were presented by their relevance to high-income countries and low–middle-income countries. Results In phase 1, 43 interventions were identified, which had low uptake in practice according to 3042 professionals globally. In phase 2, a shortlist of 15 intervention domains was generated. In phase 3, interventions were deemed acceptable for more than 90 per cent of patients except for reducing general anaesthesia (84 per cent) and re-sterilization of ‘single-use’ consumables (86 per cent). In phase 4, the top three shortlisted interventions for high-income countries were: introducing recycling; reducing use of anaesthetic gases; and appropriate clinical waste processing. In phase 4, the top three shortlisted interventions for low–middle-income countries were: introducing reusable surgical devices; reducing use of consumables; and reducing the use of general anaesthesia. Conclusion This is a step toward environmentally sustainable operating environments with actionable interventions applicable to both high– and low–middle–income countries

Cenozoic evolution of geomorphic and sedimentary environments in the Tianshui-Qinan regions

In the western Loess Plateau in northern China,the Miocene eolian sequences reported in the recent years from different sites have extended to about 22Ma ago. The eolian origin of these sequences are evidenced by (1)their wide distribution mantling the broad highlands; (2)the spatially correlative magneto- and litho-stratigraphy,magnetic susceptibility and grain-size records; (3)the presence of several hundreds of paleosols with the interbedded loess layers; (4)the fine silty textures with the maximum grain-size mostly <120μm throughout the ca.16Ma sequence; (5)the similarity of quartz grain morphology and geochemical properties to Quaternary loess;(6)the well-preserved land snails and lack of aquatic species throughout the sequences; and (7)the cyclical changes of various climate proxies along the sequences,similar to those in Quaternary loess-soil sequences in China. These Miocene eolian sequences,combined with the well-known loess-soil sequences of the last 2.6Ma and the eolian Red-Clay (8.0～2.6Ma),provide a nearly continuous terrestrial climate record since the Early Neogene.In this study,we address the evolution of geomorphic and sedimentary environments in the Tianshui-Qin'an regions where Miocene loess deposits widely spread. Earlier geological studies showed that the Tianshui and Qin'an regions are within two distinct tectonic units,which have different tectonic histories. During the Paleogene,both regions are dominated by pluvial-plain landscapes as evidenced by the widely spread pluvial sandy-gravel deposits. A tectonic event occurred near the Oligocene-Miocene boundary,leading to the formation of plateau and basin settings in these regions. Since the early Miocene,typical loess-soil sequences started to form on the plateaus while secondary loess (loess-like deposits) were formed in the basins.During Late Miocene times,the Tianshui region experienced an intense erosion leading to the formations of some small shallow lakes. Their deposits are characterized by interbedded grey-green silty-clays with coarser fluvial sandy or gravel layers. Some of them are affected by pedogenesis. These indicate that these small lakes, were frequently dried up along with the fluctuations of paleoclimates. Loess deposits in the Qin'an region have also experienced erosions,resulting in the formations of some shallow depressions in which water-reworked loess or shallow-water deposits were formed. They sometimes contained large mammalian fossils. On the contrary, typical loess-soil sequences continued to form in flat areas, that contained only micromammalian and landsnail fossils. This Late Miocene erosion period,probably characterized by several erosion events,was started ca.11Ma ago and lasted until 7Ma. It may correspond to the Late Miocene growth of the Himalayan-Tibetan complex.The basic patterns of the hilly landscape in these regions were formed in Late Pliocene or Early Pleistocene times due to another intense erosion. The severely fragmented topography of the regions since then has not been favorable for latter loess deposition,thus the Pleistocene loess is purely preserved in these regions. This Late Pliocene or Early Pleistocene erosion may be linked to another tectonic event or to the climate changes relative to the northern hemispheric cooling