Search

High-frequency driven resonant spin rotators are routinely used as standard instruments in polarization experiments in particle and nuclear physics. Maintaining the continuous exact parametric spin resonance condition of the equality of the spin rotator and the spin precession frequency during operation is one of the challenges. We present a detailed analytical description of the effects of detuning the exact spin resonance on the precessing vertical and in-plane components of the polarization. An important part of the formalism presented here is the consideration of experimentally relevant spin decoherence effects. Within the developed formalism, we address the impact of feedback via pilot-bunch-based comagnetometry on continuous spin flips and on the related interpretation of charged-particle electric dipole moment searches using storage rings. We propose a spin-flip-based tomography of the longitudinal profile of polarization in a bunch, which is important for the evaluation of the polarization-dependent luminosity in collider experiments. We emphasize the potential importance of the previously unexplored phase of the horizontal polarization of the envelope as an indicator of the stability of radio-frequency-driven spin rotations in storage rings and as a testing ground for spin decoherence mechanisms.

Based on the notion that the local dark-matter field of axions or axionlike particles (ALPs) in our Galaxy induces oscillating couplings to the spins of nucleons and nuclei (via the electric dipole moment of the latter and/or the paramagnetic axion-wind effect), we establish the feasibility of a new method to search for ALPs in storage rings. Based on previous work that allows us to maintain the in-plane polarization of a stored deuteron beam for a few hundred seconds, we perform a first proof-of-principle experiment at the Cooler Synchrotron (COSY) to scan momenta near 970 MeV/c. This entails a scan of the spin-precession frequency. At resonance between the spin-precession frequency of deuterons and the ALP-induced electric dipole moment (EDM) oscillation frequency, there is an accumulation of the polarization component out of the ring plane. Since the axion frequency is unknown, the momentum of the beam and, consequently, the spin-precession frequency are ramped to search for a vertical polarization change that occurs when the resonance is crossed. At COSY, four beam bunches with different polarization directions are used to make sure that no resonance is missed because of the unknown relative phase between the polarization precession and the axion or ALP field. A frequency window of 1.5 kHz width around the spin-precession frequency of 121 kHz is scanned. We describe the experimental procedure and a test of the methodology with the help of a radio-frequency Wien filter located on the COSY ring. No ALP resonance is observed. As a consequence, an upper limit of the oscillating EDM component of the deuteron as well as its axion coupling constants are provided.

In this paper, we demonstrate the connection between a magnetic storage ring with additional sextupole fields set so that the x and y chromaticities vanish and the maximizing of the lifetime of in-plane polarization (IPP) for a 0.97-GeV/c deuteron beam. The IPP magnitude was measured by continuously monitoring the down-up scattering asymmetry (sensitive to sideways polarization) in an in-beam, carbon-target polarimeter and unfolding the precession of the IPP due to the magnetic anomaly of the deuteron. The optimum operating conditions for a long IPP lifetime were made by scanning the field of the storage ring sextupole magnet families while observing the rate of IPP loss during storage of the beam. The beam was bunched and electron cooled. The IPP losses appear to arise from the change of the orbit circumference, and consequently the particle speed and spin tune, due to the transverse betatron oscillations of individual particles in the beam. The effects of these changes are canceled by an appropriate sextupole field setting.

This paper describes a time-marking system that enables a measurement of the in-plane (horizontal) polarization of a 0.97-GeV/c deuteron beam circulating in the Cooler Synchrotron (COSY) at the Forschungszentrum Jülich. The clock time of each polarimeter event is used to unfold the 120-kHz spin precession and assign events to bins according to the direction of the horizontal polarization. After accumulation for one or more seconds, the down-up scattering asymmetry can be calculated for each direction and matched to a sinusoidal function whose magnitude is proportional to the horizontal polarization. This requires prior knowledge of the spin tune or polarization precession rate. An initial estimate is refined by resorting the events as the spin tune is adjusted across a narrow range and searching for the maximum polarization magnitude. The result is biased toward polarization values that are too large, in part because of statistical fluctuations but also because sinusoidal fits to even random data will produce sizable magnitudes when the phase is left free to vary. An analysis procedure is described that matches the time dependence of the horizontal polarization to templates based on emittance-driven polarization loss while correcting for the positive bias. This information will be used to study ways to extend the horizontal polarization lifetime by correcting spin tune spread using ring sextupole fields and thereby to support the feasibility of searching for an intrinsic electric dipole moment using polarized beams in a storage ring. This paper is a combined effort of the Storage Ring EDM collaboration and the JEDI collaboration.

New measurements are reported for the time dependence of the vertical polarization of a 0.97 GeV/c deuteron beam circulating in a storage ring and perturbed by an rf solenoid. The storage ring is the cooler synchrotron (COSY) located at the Forschungszentrum Jülich. The beam polarization was measured continuously using a 1.5 cm thick carbon target located at the edge of the circulating deuteron beam and the scintillators of the EDDA detector. An rf solenoid mounted on the ring was used to generate fields at and near the frequency of the 1-Gγ spin resonance. Measurements were made of the vertical beam polarization as a function of time with the operation of the rf solenoid in either fixed or continuously variable frequency mode. Using rf-solenoid strengths as large as 2.66×10^{-5} revolutions/turn, slow oscillations (∼1 Hz) were observed in the vertical beam polarization. When the circulating beam was continuously electron cooled, these oscillations completely reversed the polarization and showed no sign of diminishing in amplitude. But for the uncooled beam, the oscillation amplitude was damped to nearly zero within a few seconds. A simple spin-tracking model without the details of the COSY ring lattice was successful in reproducing these oscillations and demonstrating the sensitivity of the damping to the magnitude of the synchrotron motion of the beam particles. The model demonstrates that the characteristic features of measurements made in the presence of large synchrotron oscillations are distinct from the features of such measurements when made off resonance. These data were collected in preparation for a study of the spin coherence time, a beam property that needs to become long to enable a search for an electric dipole moment using a storage ring.

A photochemical protocol for the alkylation of diazines (pyrimidines, pyrazines, and pyridazines) with N -(acyloxy)phthalimides has been developed. The process is facilitated by the presence of triethylamine under irradiation with 427–390 nm light; this enables rapid cross-coupling reactions to construct a wide range of alkylated diazines. [ABSTRACT FROM AUTHOR]

This article explores the use of ketone-derived pro-aromatic reagents for radical group transfer reactions and deconstructive functionalizations. It discusses the recent advancements in using ketones as synthetic handles for sp3-rich radicals, specifically focusing on the use of ketone-derived pro-aromatic reagents for C-C bond activation. The article highlights the synthesis and utilization of these reagents in both photochemical and non-photochemical reactions, showcasing their potential in organic radical chemistry. The authors also discuss the applications of DHQZ derivatives as radical precursors in various photoredox reactions, demonstrating their effectiveness in generating different types of alkyl and acyl radicals. The article emphasizes the versatility and potential of ketones as valuable tools in synthetic chemistry, while acknowledging the contributions of researchers from different institutions and expressing gratitude to Prof. Evelyn Creencia on her retirement. [Extracted from the article]

The original program of the NICA (Nuclotron based Ion Collider fAcility) accelerator complex is focused on a heavy ion and polarized deuteron and proton collider physics and did not include precision searches for the electric dipole moments (EDM) and the galactic axion condensate. It is of importance to note the approaches to the search for the EDM of deuterons usually discussed by CPEDM and srEDM collaborations only envision the development of a dedicated ring corresponding to the "frozen spin" mode with spin pointing all the time along the momentum due to using special deflectors with crossed electric and magnetic fields. Taking advantage of the smallness of the magnetic anomaly of deuterons, we propose to use in the NICA collider the "quasi-frozen spin" mode, when the precession of spin away from momentum in arcs is compensated by Wien filters in straight sections. The simplest technical solution at the NICA collider currently under construction is to create bypasses at the collider equipped with Wien filters, which make it possible to explore the deuteron EDM without affecting any infrastructure of the MPD and SPD detectors. Concurrently, modulation of the spin precession by Wien filters in bypasses will make NICA a broadband axion antenna. The new role of the bypass as an axion antenna, in addition to searching for the EDM of protons and deuterons, will significantly enhance the potential of the NICA complex as a unique platform for precision tests of basic symmetries in elementary particle physics [ABSTRACT FROM AUTHOR]

This article explores the use of triangulenium ions as organic photoredox catalysts in green-light-mediated reactions. Photoredox catalysis is a valuable tool in synthetic organic chemistry, but there is a need for cheaper and more sustainable catalysts. The researchers investigated the use of trianguleniums in three different reactions and found that they can act as excited-state electron acceptors or donors, depending on the reaction. This allows for the exploration of reactions involving either more-reducing or more-oxidizing substrates. The synthesis, photophysical properties, and reactivity of the trianguleniums are discussed in detail. [Extracted from the article]

This brief review is devoted to the results of non-accelerator study 01' strong nuclear long-range interaction In the mass isotope effect by the modern method of low-temperatum optical spectroscopy of condensed matter. This became possible after the discovery that the addition of one neutron causes global changes in the macroscopic characteristics of a solid. The observation of an isotopic shift (0.103 eV) of the zero-phonon line of free excitons in the luminescence spectra of LIH (without strong Interaction In the hydrogen nucleus) and UD (with strong interaction in the deuterium nucleus) crystals was the first and dlmct evidence of the long-range interaction of the Yukawa potential. Indeed, In both crystals, the lithium Ions, the proton and the electron are the same and, therefore, the gravitational, electromagnetic and weak interactions are the same, and the addition of a neutron, according to Yukawa, a strong interaction appears, the influence of which manifests itself in the isotopic shift. These experimental results demonstrate the neutron-electron binding energy (0.106 eV) which is in excellent agreement with the theoretical Breit estimate of 0.1067 eV. Another bright effect of the new physics Is associated with the isotopic creation of mass by massless fermions (leptons) in graphene. [ABSTRACT FROM AUTHOR]

Coherent spin motion is a necessary condition to search for the electric dipole moment of charged particles in a storage ring. The first step to increase the spin coherence time is to turn on a radiofrequency cavity. The next step is to manipulate equilibrium energy levels associated with betatron orbit lengthening and nonlinear momentum compaction factor. Spin resonances act as additional sources of decoherence especially for a proton beam. [ABSTRACT FROM AUTHOR]

Many children with disabilities engage in less physical activity compared to their peers. This pilot‐feasibility study examines the effects of movement‐based desk and alternative seating on classroom physical activity, time on task, reading fluency, and reading comprehension scores in fourth/fifth and seventh/eighth‐grade children with disabilities. Using a cross‐over 8‐week design, action desks were included in fourth/fifth (N = 14) and seventh/eighth (N = 21) grade classrooms for students with disabilities. Levels of physical activity were measured using accelerometers; reading ability was assessed using AIMSweb Oral Reading Fluency and MAZE probes; time on task was measured using video recordings over 3 consecutive days. Data were collected at 0‐week, 4‐week, 8‐week, 12‐week, and 16‐week time points. A significant increase in metabolic equivalent was seen in fourth/fifth graders and a significant decline in time spent in sedentary activity were observed in both fourth/fifth and seventh/eighth graders. The fourth/fifth graders increased their time spent in moderate physical activity and time on task during the intervention whereas seventh/eighth graders improved oral reading fluency. How a physical activity‐based classroom may be an effective intervention in students with disabilities to improve levels of physical activity and improve academic learning is discussed. Practitioner points: The implementation of action desks decreased sedentary activity for fourth/fifth and seventh/eighth‐grade students with disabilities.The seventh/eighth graders increased their oral reading fluency scores when using the action desks.The fourth/fifth graders had an increased amount of time on task when using the action desks. [ABSTRACT FROM AUTHOR]

Because all these parameters rarely coincide, and each variable can drastically alter the working redox potentials of the photocatalyst, [10] researchers are not able to directly compare the photocatalysts and rationally select the most appropriate one for their desired aqueous transformation. Keywords: cyclic voltammetry; photoredox catalysis; aqueous; biocompatible; sustainable EN cyclic voltammetry photoredox catalysis aqueous biocompatible sustainable 1911 1914 4 09/15/23 20231004 NES 231004 Graph One of the most important considerations when developing a new photoredox reaction is the excited-state potentials of the photocatalysts involved. Thus, when using any photocatalyst in water, it is important to consider the functional groups, namely, ionizable groups and hydrogen-bond donors and acceptors, that can augment the photochemical properties, including redox potentials, of the photocatalyst. [Extracted from the article]

In this paper, we propose a method of taking charge symmetry breaking (CSB) in hypernuclei and neutron stars into account within the framework of the Hartree–Fock approach with Skyrme interaction. The parameters of the contribution of -Skyrme force leading to CSB are derived from the corresponding parameters of the hyperon-nucleon interaction in the meson exchange models. Based on the obtained parameters, the effect of charge symmetry breaking on the hyperon binding energy in carbon hypernuclei is analyzed. The effect of charge symmetry breaking on the characteristics of neutron stars, such as their maximum mass and radii, is considered for the first time. [ABSTRACT FROM AUTHOR]

In this exploratory study, I present, for the first time, the implications of the charge symmetry breaking (CSB) that arise from the u and d quark-mass differences on gluon and sea quark distribution functions of the pion and kaon in the framework of the Nambu–Jona-Lasino (NJL) model, which is a quark-level chiral effective theory of QCD, with the help of the proper-time regularization scheme to simulate color confinement of QCD. From the analysis, one finds that the charge symmetry (CS) gluon distribution for the pion has a good agreement with the prediction results obtained from the recent lattice QCD simulation and JAM global fit QCD analysis at a higher scale of Q 2 = 5 GeV2. The size of the CSB effects on gluon and sea quark distributions for the pion with the realistic ratios of m u / m d = 0. 5 at Q 2 = 5 GeV2 are, respectively, estimated by 1.3% and 2.0% at x ≃ 1 in comparison with those for m u / m d = 1. 0 , while those for the kaon are approximately about 0.3% and 0.5% at x ≃ 1 , respectively. A remarkable result is found that the CSB effects on gluon distribution for the kaon are smaller than that for the pion, which has a similar prediction result as that for the CS case. [ABSTRACT FROM AUTHOR]

We propose a system to produce multiple spin reversals of a polarized proton beam based on orbit-steerer dipoles already installed in the Nuclotron, a superconducting synchrotron at the Joint Institute for Nuclear Research, when the latter operates in the spin-transparency regime. The beam momentum of 3.54 GeV/c corresponds to the integer spin resonance . We report the results of numerical simulation of the proton spin dynamics pertinent to the acceleration up to , including the adiabatic capture of spins by navigators and the subsequent multiple spin flips. A feasibility of the pilot experiment to verify our approach with the current magnetic lattice of the Nuclotron is discussed. To preserve the beam polarization during the crossing of integer resonances we propose to employ intentional resonance-strength enhancements effected by controlled variations of the beam orbit during acceleration. [ABSTRACT FROM AUTHOR]

Our subject is a new catalogue of radar-based heavy rainfall events (CatRaRE) over Germany and how it relates to the concurrent atmospheric circulation. We classify daily ERA5 fields of convective indices according to CatRaRE, using an array of 13 statistical methods, consisting of 4 conventional ("shallow") and 9 more recent deep machine learning (DL) algorithms; the classifiers are then applied to corresponding fields of simulated present and future atmospheres from the Coordinated Regional Climate Downscaling Experiment (CORDEX) project. The inherent uncertainty of the DL results from the stochastic nature of their optimization is addressed by employing an ensemble approach using 20 runs for each network. The shallow random forest method performs best with an equitable threat score (ETS) around 0.52, followed by the DL networks ALL-CNN and ResNet with an ETS near 0.48. Their success can be understood as a result of conceptual simplicity and parametric parsimony, which obviously best fits the relatively simple classification task. It is found that, on summer days, CatRaRE-convective atmospheres over Germany occur with a probability of about 0.5. This probability is projected to increase, regardless of method, both in ERA5-reanalyzed and CORDEX-simulated atmospheres: for the historical period we find a centennial increase of about 0.2 and for the future period one of slightly below 0.1. [ABSTRACT FROM AUTHOR]

Copyright of Momento: Revista de Física is the property of Universidad Nacional de Colombia, Departamento de Fisica and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

The spin motion is influenced by a pseudoscalar interaction with a dark matter axion field. The relativistic Hamiltonian in the Foldy-Wouthuysen representation describing the manifestation of dark matter axions in spin effects is derived. The biggest term in this Hamiltonian describes the extraordinary (three orders of magnitude) enhancement of the axion wind effect in storage ring experiments as compared with experiments with immobile particles. This term defines the spin rotation about the longitudinal axis. The effects caused by the axion-induced oscillating EDM and the axion wind consist in the spin rotations about the different horizontal axes and phases of stimulating oscillations differ by . The axion wind effect disappears when velocities of the axion and the particle coincide. [ABSTRACT FROM AUTHOR]

Copyright of Synthesis is the property of Georg Thieme Verlag Stuttgart and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

Extreme precipitation is projected to intensify with warming, but how this will manifest locally through time is uncertain. Here, we exploit an ensemble of convection-permitting transient simulations to examine the emerging signal in local hourly rainfall extremes over 100-years. We show rainfall events in the UK exceeding 20 mm/h that can cause flash floods are 4-times as frequent by 2070s under high emissions; in contrast, a coarser resolution regional model shows only a 2.6x increase. With every degree of regional warming, the intensity of extreme downpours increases by 5-15%. Regional records of local hourly rainfall occur 40% more often than in the absence of warming. However, these changes are not realised as a smooth trend. Instead, as a result of internal variability, extreme years with record-breaking events may be followed by multiple decades with no new local rainfall records. The tendency for extreme years to cluster poses key challenges for communities trying to adapt. Climate projections at km-scale show that local hourly precipitation extremes in the UK become 4-times more frequent by 2070, while they do not intensify gradually with warming, but tend to cluster in time. [ABSTRACT FROM AUTHOR]

There is now a wealth of research on obesity both from biomedical and socially critical perspectives. However, less research has focused on the lived experiences of young children and particularly those who are perceived as 'sedentary'. This paper critically examines the issue of obesity as related to children's experiences of physical (in)activity, via a focus on the circulation of socio-cultural and economic discourses in the context of Spain. We report on data obtained from interviews with 13 children identified as 'sedentary'. Data were analysed using thematic content analysis and based on the analysis a collective story was constructed to represent and give voice to the children's experiences. The collective story sketches a day in the life of 'Diego' to indirectly reveal the limitations associated with assuming that sport and school physical education (PE) are pragmatic 'answers' to the presumed issue of childhood obesity. In our analysis we draw on Foucauldian notions of bio-power and governmentality to highlight how neoliberal and capitalist logics shape and constrain children's experiences and opportunities. By presenting a narrative that delves into the various domains of these children's lives, their families, friends, peers and lifestyles, we argue there is still a need to reformulate and rethink how we understand childhood wellbeing and the role of PE. We conclude by suggesting that the conflation of PE with sport and health can subtly undermine some children's views of self. [ABSTRACT FROM AUTHOR]

Estimating future short-duration extreme precipitation in mountainous regions is fundamental for risk management. High-resolution convection-permitting models (CPMs) represent the state of the art for these projections, as they resolve convective processes that are key to short-duration extremes. Recent observational studies reported a decrease in the intensity of extreme hourly precipitation with elevation. This "reverse orographic effect" could be related to processes which are subgrid even for CPMs. To quantify the reliability of future projections of extreme short-duration precipitation in mountainous regions, it is thus crucial to understand to what extent CPMs can reproduce this effect. Due to the computational demands however, CPM simulations are still too short for analyzing extremes using conventional methods. We use a non-asymptotic statistical approach (Simplified Metastatistical Extreme Value: SMEV) for the analysis of extremes from short time periods, such as the ones of CPM simulations. We analyze an ERA-Interim-driven Consortium for Small-Scale Modeling (COSMO-crCLIM, convection-resolving Climate Modelling) simulation (2000–2009; 2.2 km resolution), and we use hourly precipitation from 174 rain gauges in an orographically complex area in northeastern Italy as a benchmark. We investigate the ability of the model to simulate the orographic effect on short-duration precipitation extremes, as compared to observational data. We focus on extremes as high as the 20-year return levels. While overall good agreement is reported at daily and hourly duration, the CPM tends to increasingly overestimate hourly extremes with increasing elevation, implying that the reverse orographic effect is not fully captured. These findings suggest that CPM bias-correction approaches should account for orography. SMEV's capability of estimating reliable rare extremes from short periods promises further applications on short-time-period CPM projections and model ensembles. [ABSTRACT FROM AUTHOR]

The complement component C3 is a fundamental plasma protein for host defense, produced largely by the liver. However, recent work has demonstrated the critical importance of tissue-specific C3 expression in cell survival. Here, we analyzed the effects of local versus peripheral sources of C3 expression in a model of acute bacterial pneumonia induced by Pseudomonas aeruginosa. Whereas mice with global C3 deficiency had severe pneumonia-induced lung injury, those deficient only in liver-derived C3 remained protected, comparable to wild-type mice. Human lung transcriptome analysis showed that secretory epithelial cells, such as club cells, express high levels of C3 mRNA. Mice with tamoxifen-induced C3 gene ablation from club cells in the lung had worse pulmonary injury compared with similarly treated controls, despite maintaining normal circulating C3 levels. Last, in both the mouse pneumonia model and cultured primary human airway epithelial cells, we showed that stress-induced death associated with C3 deficiency parallels that seen in Factor B deficiency rather than C3a receptor deficiency. Moreover, C3-mediated reduction in epithelial cell death requires alternative pathway component Factor B. Thus, our findings suggest that a pathway reliant on locally derived C3 and Factor B protects the lung mucosal barrier. Lung protection by local complement: Complement proteins are innate immune defense molecules that protect the host against pathogenic microorganisms. The activities of the C3 component of complement are mostly attributed to circulating C3 primarily synthesized by hepatocytes. Sahu and Ozantürk et al. used mouse models of conditional gene deletion to investigate the contribution of local C3 protein production in the lung to protecting the pulmonary mucosal surface from cell damage caused by Pseudomonas aeruginosa infection. Mice lacking C3 only in lung epithelial cells exhibited more pronounced acute lung injury than control mice even so circulating C3 levels were maintained at near-normal levels by maintenance of liver C3 production. These findings point to lung epithelial cell-intrinsic protective functions provided by C3 as an essential contributor to first-line defense against bacterial pneumonia.—IRW [ABSTRACT FROM AUTHOR]

The Weather Research and Forecasting (WRF) model was applied to simulate the current and future climates over eastern China at a convection‐permitting resolution (∼4 km). A continuous 10‐year (1998–2007) simulation was performed for the historical climate, and three pseudo‐global warming (PGW) experiments driven by climate perturbations during 2070–2099 were conducted under the RCP2.6, RCP4.5, and RCP8.5 scenarios. After validation against reanalysis and observational data, the historical simulation was found capable of reasonably reproducing the characteristics of mean precipitation, extreme hourly precipitation, and large‐scale circulation. The PGW experiments projected an increase in precipitation intensity over most regions, especially North China under the RCP8.5 scenario (up to 30%). However, the precipitation frequency was projected to decrease, especially over the Yangtze River Basin in summer. A wetting (drying) trend was observed over North China (South China) in summer (winter), due to the increase (decrease) in precipitation intensity (frequency). The intensity and frequency of extreme events were projected to increase over most areas of eastern China, and the increase was the most dramatic under the RCP8.5 scenario, indicating a greater flood risk under stronger global warming. The relationship between extreme precipitation and temperature (EP–T) displayed a hook‐shape structure in both the present and future climates. The extreme precipitation intensity increased with temperature at a super Clausius–Clapeyron (C–C) scaling rate (>7%/K) until reaching a peak at temperatures of around 25–29°C, and then decreased at higher temperatures. The decreases were mainly attributed to moisture limitation at high temperatures. In the future, the EP–T relationship is expected to change mostly following the C–C law, with greater precipitation peaks under scenarios with higher carbon emissions, indicating that warmer climates contribute to further enhancement of extreme precipitation. Plain Language Summary: The extreme precipitation–temperature (EP–T) scaling relation is a useful conceptual tool for understanding the changes in extreme precipitation in present and future climates. EP‐T relation is related to Clausius–Clapeyron (C–C) relationship which indicates that precipitation is expected to increase by 7% for each degree of temperature increasing. However, EP‐T relation can deviate from the C–C scaling according to studies based on observations and numerical models. The relation between hourly EP and T is essential for predicting instantaneous weather hazards over eastern China, but such relation was not well reproduced by previous studies using GCMs with coarser resolution. In this study, we investigated the current and future hourly EP–T relation over eastern China using high‐resolution (4 km) convection‐permitting RCM (CP‐RCM). Our analysis indicates that CP‐RCM can well reproduce the characteristics of extreme hourly precipitation and large‐scale circulation. Precipitation intensity will increase but precipitation frequency will decrease in the future over eastern China. The EP–T relation displays a hook‐shape structure in both the present and future climates mainly due to moisture limitation at higher temperatures. The warmer the future climates, the more intense the extreme precipitation. Key Points: Future changes in precipitation over eastern China were assessed using pseudo‐global warming simulations at a convective‐permitting resolutionHourly extreme precipitation was projected to be more frequent and intense over eastern China in the future, while light and moderate rain will likely decreaseHourly extreme precipitation and temperature over eastern China displayed a hook‐shape relationship, due to moisture limitation at high temperatures [ABSTRACT FROM AUTHOR]

Visible light photocatalysis has established itself as a promising sustainable and powerful strategy to access reactive intermediates, i.e. radicals and radical ions, under mild reaction conditions using visible light irradiation. This field enables the development of formerly challenging or even previously inaccessible organic transformations. In this tutorial review, an overview of the essential concepts and techniques of visible-light-mediated chemical processes and the most common types of photochemical activation of organic molecules, i.e. photoredox catalysis and photosensitization, are discussed. Selected photocatalytic alkene functionalization reactions are included as examples to illustrate the basic concepts and techniques with particular attention given to the understanding of their reaction mechanisms. 1 Introduction 2 Photocatalysts 3 Photophysical and Electrochemical Properties 3.1 Excited-State Energy 3.2 Ground-State Redox Potentials 3.3 Excited-State Redox Potentials 3.4 Local Absorbance Maximum for Lowest Energy Absorption 3.5 Excited-State Lifetime 3.6 [Ru(bpy)3 ]2+ as a Case Study 3.7 Basic Laws and Equations of Photochemistry and Photocatalysis 3.8 Common Terminology in Photochemistry and Photocatalysis 4 Activation Modes in Photocatalysis 4.1 Photoinduced Electron Transfer 4.2 Photoinduced Energy Transfer 5 Conclusions and Outlook [ABSTRACT FROM AUTHOR]

A visible-light-driven α-hydroxymethylation of ketones to generate the corresponding alcohols was achieved under continuous-flow conditions. MeOH was used as a green and renewable C1 source and solvent to enable the α-C(sp3)–H functionalization of ketones under irradiation by white LEDs. A flow microreactor operated under optimized conditions permitted this oxidation to proceed with a higher efficiency and a shortened reaction time of 215 minutes, which was improved ten times compared with the batch parallel reaction (36 h). Mechanism studies indicate the reaction proceeds by a radical pathway. [ABSTRACT FROM AUTHOR]

Coarse resolution datasets often poorly capture precipitation properties. It is commonly expected that skill at the local level should increase by refining spatial resolution. Here, we examine the influence of spatial resolution on the accuracy of means and extremes in precipitation by comparing high‐resolution dynamically downscaled data against the driving lower‐resolution reanalysis. We show that the higher‐resolution data are less accurate than lower‐resolution data for both mean and extreme precipitation. The quantitative deterioration (increase in the domain averaged relative error) from coarse to high resolution varies typically between 1%–8% and 5%–30% for mean and extreme precipitation, respectively. We also find that the finer‐scale variability resolved only by the higher‐resolution system and successfully predicted by that system is of negligible magnitude compared to the overall error (less than 1%). We conclude that finer‐scale resolution by itself does not necessarily bring a meaningful improvement in local simulation accuracy. Plain Language Summary: In this study, we examined the impact of spatial resolution on means and extremes in precipitation using high‐resolution dynamically downscaled data against the driving lower‐resolution reanalysis over Australia. We report that high‐resolution data are less accurate than lower resolution data for standard statistics of precipitation. We also discuss the possible reasons for the deterioration and variations between previous studies. The results highlight that increasing the horizontal resolution alone will not help address problems with precipitation. Significant model developments and data assimilation techniques are required to reap the benefits of high horizontal resolution. Key Points: Increasing the horizontal resolution alone did not help address problems with simulating regional precipitation in this case studySignificant model developments are required to reap the benefits of high horizontal resolution [ABSTRACT FROM AUTHOR]

A convection‐permitting regional climate model (CPRCM) with 2.5 km resolution has been simulated over South Korea for current and future conditions, and the role of convection in the scaling of hourly extreme precipitation (EP) with temperature is examined. It is found that the CPRCM can reproduce the observed super Clausius‐Clapeyron (C‐C) scaling for hourly EP. Precipitation type estimated based on the convective available potential energy reveals the important role of convection in the super C‐C scaling. Fraction of convective rainfall events increases rapidly with temperature, and the contribution of convection becomes dominant in future simulations under high‐emission scenarios. In the late 21st century, as temperature ranges shift to warmer conditions, unprecedented hourly extreme rainfall events are projected to occur particularly during the late summer season. Future changes in hourly extreme events are found to be affected much by boundary conditions from different global climate models. Plain Language Summary: The role of convection in the scaling of hourly extreme precipitation (EP) with temperature is examined using convection‐permitting regional climate model simulations. The convection‐permitting model has been simulated over South Korea with 2.5 km resolution for current and future conditions. The model is found to capture the observed super Clausius‐Clapeyron (C‐C) scaling, which is underestimated by a low resolution simulation based on convective parameterization. When analyzing contributions of convective versus non‐convective type events based on convective available potential energy, convective events are found to be more important in shaping the super C‐C scaling. As the proportion of convective precipitation increases rapidly with warming, the role of convection in the scaling becomes dominant. Future projections under high emission scenarios indicate the occurrence of unprecedented hourly EP events during the late summer season. It is also found that global climate model boundary conditions affect the EP‐temperature scaling by providing different background warming rates. Key Points: Convection‐permitting model reproduces the observed super Clausius‐Clapeyron scaling for hourly extreme precipitation over South KoreaPrecipitation type analysis using convective available potential energy reveals the important role of convection in the scalingThe role of convection becomes dominant in the high‐emission scenario, resulting in unprecedented extreme rainfall events in late summer [ABSTRACT FROM AUTHOR]

From a health promotion perspective, schools are ideal settings for the promotion of physical activity since virtually all children and youth can be reached. Physical education is mandatory in many countries and offers unique opportunities for the promotion of physical activity among children and youth. However, since physical education represents a rather small proportion of the total waking hours among children and youth, it is important to determine the influence of physical education on daily physical activity among children and youth. While studies indicate that children and youth are physically active during physical education and that interventions might increase physical activity even further, the individual contribution of physical education to daily physical activity appears promising but not conclusive. [ABSTRACT FROM AUTHOR]

A convenient approach to previously poorly accessible α,α-difluoroalkyl alcohols by visible light-mediated photocatalysis was developed. Broad scope of the transformation together with experimental simplicity and scalability using flow techniques open good prospects for further studies of properties (including biological) of these novel products. [ABSTRACT FROM AUTHOR]

The relativistic spin dynamics defined by the pseudoscalar field of dark matter axions is rigorously determined. The relativistic Hamiltonian in the Foldy–Wouthuysen representation is derived. It agrees with the previously obtained nonrelativistic Hamiltonians and the relativistic classical estimation of the axion wind effect. In the relativistic Hamiltonian, the biggest term describes the extraordinary (three orders of magnitude) enhancement of the axion wind effect in storage ring experiments as compared with experiments with immobile particles. This term defines the spin rotation about the longitudinal axis. The effects caused by the axion-induced oscillating EDM and the axion wind consist in the spin rotations about the different horizontal axes and phases of stimulating oscillations differ by π / 2 . Experiments in a search for dark matter axions has been discussed. The two experimental designs for axion search experiments in storage rings have been elaborated. [ABSTRACT FROM AUTHOR]

Climate change is one of the biggest challenges currently faced by society, with an impact on many systems, such as the hydrological cycle. To assess this impact in a local context, regional climate model (RCM) simulations are often used as input for rainfall-runoff models. However, RCM results are still biased with respect to the observations. Many methods have been developed to adjust these biases, but only during the last few years, methods to adjust biases that account for the correlation between the variables have been proposed. This correlation adjustment is especially important for compound event impact analysis. As an illustration, a hydrological impact assessment exercise is used here, as hydrological models often need multiple locally unbiased input variables to ensure an unbiased output. However, it has been suggested that multivariate bias-adjusting methods may perform poorly under climate change conditions because of bias nonstationarity. In this study, two univariate and four multivariate bias-adjusting methods are compared with respect to their performance under climate change conditions. To this end, a case study is performed using data from the Royal Meteorological Institute of Belgium, located in Uccle. The methods are calibrated in the late 20th century (1970–1989) and validated in the early 21st century (1998–2017), in which the effect of climate change is already visible. The variables adjusted are precipitation, evaporation and temperature, of which the former two are used as input for a rainfall-runoff model, to allow for the validation of the methods on discharge. Although not used for discharge modeling, temperature is a commonly adjusted variable in both uni- and multivariate settings and we therefore also included this variable. The methods are evaluated using indices based on the adjusted variables, the temporal structure, and the multivariate correlation. The Perkins skill score is used to evaluate the full probability density function (PDF). The results show a clear impact of nonstationarity on the bias adjustment. However, the impact varies depending on season and variable: the impact is most visible for precipitation in winter and summer. All methods respond similarly to the bias nonstationarity, with increased biases after adjustment in the validation period in comparison with the calibration period. This should be accounted for in impact models: incorrectly adjusted inputs or forcings will lead to predicted discharges that are biased as well. [ABSTRACT FROM AUTHOR]

All-polymer solar cells (all-PSCs) have significantly improved long-term stability and mechanical stretchability. The power conversion efficiency (PCE) of all-PSCs has been rapidly improved from ∼1% to now over ∼17%, driven by rational molecular design, blend morphology optimization, and device engineering. However, most all-PSCs are generally processed with halogenated solvents, hazardous for human health and the global environment. Achieving high-performance all-PSCs with halogen-free solvent processing remains a challenge. This feature article presents recent advances in green-solvent-processable all-PSCs from the material design and morphological control perspective, and further reviews progress in using more environmentally friendly solvents (i.e., water or alcohol) to achieve genuinely sustainable and environmentally friendly manufacturing all-PSCs. Finally, we provide an outlook on the challenges and opportunities for large-scale manufacturing of green-solvent-processable all-PSCs. [ABSTRACT FROM AUTHOR]

The synthesis of a set of new organic photocatalysts (PCs) with a donor-acceptor carbazolyl dicyanobenzene structure is reported. The PCs developed have fine-tailored redox potentials from –1.62 V (PC•+ /PC*) to 1.36 V (PC*/PC•–) and were accessed through a straightforward two-step synthesis. The potential of these PCs was demonstrated in synthetically relevant reactions with mechanistically opposite thermodynamic requirements, previously reported only in the presence of precious Ir-based PCs. In addition, the PCs outperformed the yields promoted by the well-established 4CzIPN organic dye in both type of reactions. [ABSTRACT FROM AUTHOR]

The increasing use of acridinium photocatalysts as sustainable alternative to precious metal-based counterparts encourages the design and efficient synthesis of distinct catalyst structures. Herein, we report our exploration of the scope of the aryne–imine–aryne coupling reaction combined with a subsequent acridane oxidation for a short two-step approach towards various acridinium salts. The photophysical properties of the novel photocatalysts were investigated and the practical value was demonstrated by a cation-radical accelerated nucleophilic aromatic substitution reaction. [ABSTRACT FROM AUTHOR]

The regioselectivity of the intramolecular cyclization of bifunctional α-phenyl alkenes can be controlled simply by the choice of the organic chromophore as the photocatalyst. The central photoredox catalytic reaction in both cases is a nucleophilic addition of the hydroxy function to the olefin function of the substrates. N , N -(4-Diisobutylaminophenyl)phenothiazine catalyzes exo -trig cyclizations, whereas 1,7-dicyanoperylene-3,4,9,10-tetracarboxylic acid bisimides catalyze endo -trig additions to products with anti-Markovnikov regioselectivity. We preliminarily report the photoredox catalytic conversions of 11 representative substrates into 20 oxaheterocycles in order to demonstrate the similarity, but also the complementarity, of these two variants in this photoredox catalytic toolbox. [ABSTRACT FROM AUTHOR]

Host–guest assemblies of a designed 1,4-bis(diarylamino)naphthalene and V-shaped aromatic amphiphiles consisting of two pentamethylbenzene moieties bridged by an m -phenylene unit bearing two hydrophilic side chains emerged as highly reducing photoredox catalysis systems in water. An efficient demethoxylative hydrogen transfer of Weinreb amides has been developed. The present supramolecular strategy permits facile tuning of visible-light photoredox catalysis in water. [ABSTRACT FROM AUTHOR]

Organic photoredox catalysts with a long excited-state lifetime have emerged as promising alternatives to transition-metal-complex photocatalysts. This paper explains the effectiveness of using long-lifetime photoredox catalysts for organic transformations, focusing on the structures and photophysics that enable long excited-state lifetimes. The electrochemical potentials of the reported organic, long-lifetime photocatalysts are compiled and compared with those of the representative Ir(III)- and Ru(II)-based catalysts. This paper closes by providing recent demonstrations of the synthetic utility of the organic catalysts. 1 Introduction 2 Molecular Structure and Photophysics 3 Photoredox Catalysis Performance 4 Catalysis Mediated by Long-Lifetime Organic Photocatalysts 4.1 Photoredox Catalytic Generation of a Radical Species and its Addition to Alkenes 4.2 Photoredox Catalytic Generation of a Radical Species and its Addition to Arenes 4.3 Photoredox Catalytic Generation of a Radical Species and its Addition to Imines 4.4 Photoredox Catalytic Generation of a Radical Species and its Addition to Substrates Having C≡X Bonds (X=C, N) 4.5 Photoredox Catalytic Generation of a Radical Species and its Bond Formation with Transition Metals 4.6 Miscellaneous Reactions of Radical Species Generated by Photoredox Catalysis 5 Conclusions [ABSTRACT FROM AUTHOR]

Comprehensive Summary: A three‐component reaction of 1,3‐enynes and cyclobutanone oxime esters in the presence of aryl boronic acids or organozinc reagents via the photoredox/copper or photoredox/nickel catalysis has been established. This redox‐neutral 1,4‐cyanoalkylarylation reaction has demonstrated mild condition, high catalytic reactivity and wide functional group compatibility, allowing access to a variety of functionalized tetra‐substituted allene derivatives with high chemo‐ and regioselectivity. Moreover, using photocatalytic continuous flow technique to promote this process would result in increased yields (70% in flow vs. 61% in batch), reduced reaction times (7 min in flow vs. 6 h in batch), and easy scale‐up (upgrade to gram scale), showcasing its potential as a synthetic platform. [ABSTRACT FROM AUTHOR]

The charge-exchange strength functions for the isotopes Mo are presented. Both experimental data obtained for the strength functions in () and ( He, ) reactions and the strength functions calculated within the self-consistent theory of finite Fermi systems are analyzed. The resonance structure of the strength function is investigated, and the Gamow–Teller, analog, and pygmy resonances are isolated. The quenching effect manifesting itself as a sum-rule shortfall, which changes the normalization of the strength function , is studied. It is indicated that the resonance structure of the strength function is of decisive importance for the calculation and analysis of neutrino capture by nuclei. [ABSTRACT FROM AUTHOR]

We report the attempted development of a photoredox-catalyzed α-C–H alkylation reaction of aliphatic amine derivatives, using N-tosylhydrazones as radical alkylating partners. The original intention was to intercept α-aminoalkyl radical intermediates with N-tosylhydrazones, followed by the expulsion of a sulfonyl radical by β-scission to generate N-H diazene species. Facile denitrogenation of these intermediates would remove all traces of the hydrazone moiety and provide a net C–H alkylation process. However, our plans were derailed by issues with the low reactivity of N-tosylhydrazones toward intermolecular capture by nucleophilic radicals, and several unexpected side reactions. Our findings, though unsuccessful, do serve to identify challenges for future researchers attempting to develop similar transformations. [ABSTRACT FROM AUTHOR]

In this Account, we summarize the contributions of our group to the field of photochemistry and photocatalysis. Our work deals with the development of novel synthetic methods based on the exploitation of photoexcited aryl ketones. The application of new technologies, such as microfluidic photoreactors (MFPs), has enhanced the synthetic performance and scalability of several photochemical methods, e.g., Paternò–Büchi and photoenolization/Diels–Alder processes, while opening the way to unprecedented reactivity. In addition, careful mechanistic analysis of the developed methods has been instrumental in disclosing a new family of powerful organic photocatalysts that can mediate several thermodynamically extreme photoredox processes. 1 Introduction 1.1 Shining Light on Aryl Ketones: From the Historical Background to Recent Synthetic Applications 1.2 Preliminary Mechanistic Considerations 2 Synthetic Transformations Driven by Triplet State Benzophenones 3 Synthetic Transformations Driven by Triplet State o -Alkyl-Substituted Benzophenones 4 The Evolution of Aryl-Ketone-Derived Products: Applications in Organophotoredox Catalysis 5 Conclusions and Future Directions [ABSTRACT FROM AUTHOR]

Understanding and modelling pluvial flood patterns is pivotal for the estimation of flood impacts in urban areas, especially in a climate change perspective. However, urban flood modelling under climate change conditions poses several challenges. On one hand, the identification and collection of climate change data suitable for flood‐related evaluations requires consistent computational and scientific effort. On the other hand, large difficulties can arise in the reproduction of the rainfall‐runoff transformation process in cases when only little information about the subsurface processes is known. In this perspective, a simplified approach is proposed to address the challenges regarding the quantitative estimation of climate change effects on urban flooding for real case applications. The approach is defined as "bottom‐up" because climate change information is not included in flood modelling, but it is only invoked for the interpretation of results. In other words, the challenge faced in this work is the development of a modelling strategy that is expeditious, because it does not require flood simulations for future rainfall scenarios, but only under current climate conditions, thus reducing the overall computational effort; and it is flexible, because results can be easily updated once new climate change data, scenarios or methods become available, without the need of additional flood simulations. To simulate real case applications, the approach is tested for a scenario analysis, where different return periods and hyetograph shapes are used as input for urban inundation modelling in Naples, Italy. The approach can support public and private stakeholders, such as land administrators and water systems managers; moreover, it represents a valuable and effective basis for climate change risk communication strategies. [ABSTRACT FROM AUTHOR]

Approximately 10 years ago, convection‐permitting regional climate models (CPRCMs) emerged as a promising computationally affordable tool to produce fine resolution (1–4 km) decadal‐long climate simulations with explicitly resolved deep convection. This explicit representation is expected to reduce climate projection uncertainty related to deep convection parameterizations found in most climate models. A recent surge in CPRCM decadal simulations over larger domains, sometimes covering continents, has led to important insights into CPRCM advantages and limitations. Furthermore, new observational gridded datasets with fine spatial and temporal (~1 km; ~1 h) resolutions have leveraged additional knowledge through evaluations of the added value of CPRCMs. With an improved coordination in the frame of ongoing international initiatives, the production of ensembles of CPRCM simulations is expected to provide more robust climate projections and a better identification of their associated uncertainties. This review paper presents an overview of the methodology to produce CPRCM simulations and the latest research on the related added value in current and future climates. Impact studies that are already taking advantage of these new CPRCM simulations are highlighted. This review paper ends by proposing next steps that could be accomplished to continue exploiting the full potential of CPRCMs. This article is categorized under:Climate Models and Modeling > Earth System Models [ABSTRACT FROM AUTHOR]