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Abstract We report on the first production of an antihydrogen beam by charge exchange of 6.1 keV antiprotons with a cloud of positronium in the GBAR experiment at CERN. The 100 keV antiproton beam delivered by the AD/ELENA facility was further decelerated with a pulsed drift tube. A 9 MeV electron beam from a linear accelerator produced a low energy positron beam. The positrons were accumulated in a set of two Penning–Malmberg traps. The positronium target cloud resulted from the conversion of the positrons extracted from the traps. The antiproton beam was steered onto this positronium cloud to produce the antiatoms. We observe an excess over background indicating antihydrogen production with a significance of 3–4 standard deviations.

Abstract JEM-EUSO is an international program for the development of space-based Ultra-High Energy Cosmic Ray observatories. The program consists of a series of missions which are either under development or in the data analysis phase. All instruments are based on a wide-field-of-view telescope, which operates in the near-UV range, designed to detect the fluorescence light emitted by extensive air showers in the atmosphere. We describe the simulation software ESAF in the framework of the JEM-EUSO program and explain the physical assumptions used. We present here the implementation of the JEM-EUSO, POEMMA, K-EUSO, TUS, Mini-EUSO, EUSO-SPB1 and EUSO-TA configurations in ESAF. For the first time ESAF simulation outputs are compared with experimental data.

We present a new measurement of the Λ4H hypernuclear lifetime using in-flight K− + 4He → Λ4H + π0 reaction at the J-PARC hadron facility. We demonstrate, for the first time, the effective selection of the hypernuclear bound state using only the γ-ray energy decayed from π0. This opens the possibility for a systematic study of isospin partner hypernuclei through comparison with data from (K−, π−) reaction. As the first application of this method, our result for the Λ4H lifetime, τ(HΛ4)=206±8(stat.)±12(syst.)ps, is one of the most precise measurements to date. We are also preparing to measure the lifetime of the hypertriton (Λ3H) using the same setup in the near future.

Superconducting (SC) tokamak JT-60SA plays an essential role in fusion research and development by supporting and complementing the ITER project, providing directions to the DEMO design activity and fostering next generation scientists and engineers. Since the short circuit incident at the terminal joints of equilibrium field coil #1 during the integrated commissioning (IC) in March 2021, both EU and JA implementing agencies (IAs) have examined how to ensure safe operation of JT-60SA by mitigating the risk of possible discharge occurrence inside the cryostat. Based on the experience of the global Paschen tests, the IAs have established a strategy of risk mitigation measures, which is a combination of (i) reinforcement of insulation, (ii) avoiding unnecessary voltage application to the coil systems and (iii) immediate de-energization of the coils when deteriorated vacuum conditions are detected. Thanks to the considerable efforts of the Integrated Project Team members, the IC restarted in May 2023. After confirmation of the SC state of the coil systems (TF, EF and CS), the coil energization test and the plasma operation phase 1 (OP-1) started. The first plasma was successfully achieved on 23 October 2023 with a limited value of voltage and current applied to the coils. The plasma configuration control was also confirmed with low plasma current and low auxiliary heating power conditions. Based on the IO–F4E–QST collaboration, activities of JT-60SA have been shared with the IO and provided an important lesson for ITER assembly and commissioning, and will provide an outstanding contribution to fusion research at large. After OP-1, maintenance & enhancement phase 1 (M/E-1) starts from January 2024, in which in-vessel components are installed, and heating and diagnostic systems are extensively upgraded to allow a high power heating experiment planned in OP-2. In order to make the best use of JT-60SA, a newly organized JT-60SA experiment team will refine the research plan for the future high heating power operation phase.

Effects of the kinetic thermal ions (KTIs) on ideal infernal modes and resistive infernal modes have been investigated by using magnetohydrodynamic (MHD) simulation without KTIs and kinetic-MHD hybrid simulation with KTIs. For the ideal infernal modes, the pressure profile is significantly flattened at the saturated state for both the models with and without the KTIs. As the beta value decreases, the ideal infernal modes are stabilized while the resistive infernal modes are still unstable. For the resistive infernal modes, while the saturated pressure profile is significantly flattened in the MHD simulation without KTIs, the pressure profile is not flattened at the saturated state in the kinetic-MHD hybrid simulation with KTIs. The suppression of the saturation level by the effects of the KTIs results from the phase mismatch between the radial velocity and perturbed pressure mode structures. This indicates that KTIs play an essential role for the suppression of pressure profile flattening due to slowly growing resistive MHD instabilities.

We measured a set of π±Σ∓, π0Σ0, and π−Σ0 invariant mass spectra below and above the K¯N mass threshold in K−-induced reactions on deuteron. The measured πΣ mass spectral shape is well reproduced via the two-step mechanism, i.e., a neutron knocked out at a forward angle from a deuteron by an incident K−, with the K¯ recoiled backward reacting with the residual nucleon to produce π and Σ. We deduced the S-wave K¯N→πΣ and K¯N→K¯N scattering amplitudes in the isospin 0 channel in the framework of a K¯N and πΣ coupled channel. We find that a resonance pole corresponding to Λ(1405) is located at 1417.7−7.4+6.0 (fitting errors)−1.0+1.1 (systematic errors) + [−26.1−7.9+6.0 (fitting errors)−2.0+1.7 (systematic errors)] i MeV/c2, closer to the K¯N mass threshold than the value determined by the Particle Data Group.

ABSTRACT: To facilitate sustainable dairy farming, it is essential to assess and support the mental health of dairy farm workers, which is affected more than that of workers in other industries, as indicated by the relatively few studies to date. In addition, the limited investigations on mental health in dairy workers minimize the opportunities to suggest practical approaches of improvement of their mental health. Therefore, further data acquisition and analysis is required. In the present study, we undertook quantitative surveys on 17 management factors and administered a mental health questionnaire to 81 dairy farm managers (80 male, 1 female) in Hokkaido, northern Japan. The management factors were categorized into 3 groups: production input, production output, and facility indicator; mental health was evaluated based on the Center for Epidemiologic Studies Depression Scale (CES-D). Principal component analysis assigned the factors into 2 groups: intensiveness factors of dairy production systems (PC1: livestock care cost, fat- and protein-corrected milk, stocking density, medical consultation fee per unit time per animal unit, nonfamily wages, fertilizer and pesticide expenses, and net agricultural income ratio) and basic dairy management factors (PC2: net agricultural income ratio, quantity of concentrate feed, and milk quality variable). The depression symptoms of dairy farm managers were not significantly associated with PC1 and milking methods; however, they were significantly negatively associated with PC2, which integrated 3 management factors, including factors related to finances, feeding, and milk quality. According to the findings of the present study, the efforts needed for stable economic farm management, adequate feed supply, and milk quality maintenance may increase the depression levels of dairy farm managers and negatively affect their mental health. These findings could be the basis for future studies on the relationship between the mental health of farm managers and sustainable dairy farm management and production.

This paper concerns the interaction between solitary waves on the surface of an ideal fluid and a localized external force, which models a moving disturbance on the free surface or an obstacle moving at the bottom of a channel. Previous works have investigated this interaction under the assumption that the external force moves with variable speed and constant acceleration. However, in this paper we adopt a different approach and consider the scenario in which the external force moves with variable speed and non-constant acceleration. Using the Whitham equation framework, we investigate numerically trapped waves excited by a periodic external force. Our experiments reveal regimes in which solitary waves are spontaneously generated and trapped for large times at the external force. In addition, we compare the results predicted by the Whitham equation with those of the Korteweg–de Vries equation.

Abstract The MMX infrared spectrometer (MIRS) is an imaging spectrometer onboard MMX JAXA mission. MMX (Martian Moon eXploration) is scheduled to be launched in 2024 with sample return to Earth in 2029. MIRS is built at LESIA-Paris Observatory in collaboration with four other French laboratories, collaboration and financial support of CNES and close collaboration with JAXA and MELCO. The instrument is designed to fully accomplish MMX’s scientific and measurement objectives. MIRS will remotely provide near-infrared spectral maps of Phobos and Deimos containing compositional diagnostic spectral features that will be used to analyze the surface composition and to support the sampling site selection. MIRS will also study Mars atmosphere, in particular spatial and temporal changes such as clouds, dust and water vapor. Graphical Abstract

Background The epidemiology of childhood SARS-CoV-2 infection and COVID-19-related illness remains little studied in high-transmission tropical settings, partly due to the less severe clinical manifestations typically developed by children and the limited availability of diagnostic tests. To address this knowledge gap, we investigate the prevalence and predictors of SARS-CoV-2 infection (either symptomatic or not) and disease in 5 years-old Amazonian children. Methodology/Principal findings We retrospectively estimated SARS-CoV-2 attack rates and the proportion of infections leading to COVID-19-related illness among 660 participants in a population-based birth cohort study in the Juruá Valley, Amazonian Brazil. Children were physically examined, tested for SARS-CoV-2 IgG and IgM antibodies, and had a comprehensive health questionnaire administered during a follow-up visit at the age of 5 years carried out in January or June-July 2021. We found serological evidence of past SARS-CoV-2 infection in 297 (45.0%; 95% confidence interval [CI], 41.2–48.9%) of 660 cohort participants, but only 15 (5.1%; 95% CI, 2.9–8.2%) seropositive children had a prior medical diagnosis of COVID-19 reported by their mothers or guardians. The period prevalence of clinically apparent COVID-19, defined as the presence of specific antibodies plus one or more clinical symptoms suggestive of COVID-19 (cough, shortness of breath, and loss of taste or smell) reported by their mothers or guardians since the pandemic onset, was estimated at 7.3% (95% CI, 5.4–9.5%). Importantly, children from the poorest households and those with less educated mothers were significantly more likely to be seropositive, after controlling for potential confounders by mixed-effects multiple Poisson regression analysis. Likewise, the period prevalence of COVID-19 was 1.8-fold (95%, CI 1.2–2.6-fold) higher among cohort participants exposed to food insecurity and 3.0-fold (95% CI, 2.8–3.5-fold) higher among those born to non-White mothers. Finally, children exposed to household and family contacts who had COVID-19 were at an increased risk of being SARS-CoV-2 seropositive and–even more markedly–of having had clinically apparent COVID-19 by the age of 5 years. Conclusions/Significance Childhood SARS-CoV-2 infection and COVID-19-associated illness are substantially underdiagnosed and underreported in the Amazon. Children in the most socioeconomically vulnerable households are disproportionately affected by SARS-CoV-2 infection and disease. Author summary The epidemiology of childhood COVID-19 in the tropics remains a relatively neglected research topic, in part because SARS-CoV-2 typically causes fewer severe illnesses, hospitalizations, and deaths in children than in adults. Here we show that 45% of 660 participants in a birth cohort study in the Brazilian Amazon had SARS-CoV-2 antibodies at the age of 5 years, although only 5% of them reported previously diagnosed COVID-19 episodes–implying that as many as 8 in 9 SARS-CoV-2 infections had remained undiagnosed in these young children. Only 16% of the seropositive children had reportedly experienced cough, shortness of breath, and/or loss of taste or smell. The most socioeconomically vulnerable participants were more likely to have experienced SARS-CoV-2 infection and overt COVID-19 by the age of 5 years. Importantly, children exposed to household food insecurity, which affects 54% of our study participants, had their COVID-19 risk increased by 76%.

Respiratory diseases commonly affect livestock species, negatively impacting animal’s productivity and welfare. The use of precision livestock farming (PLF) applied in respiratory disease detection has been developed for several species. The aim of this systematic review was to evaluate if PLF technologies can reliably monitor clinical signs or detect cases of respiratory diseases. A technology was considered reliable if high performance was achieved (sensitivity > 90% and specificity or precision > 90%) under field conditions and using a reliable reference test. Risk of bias was assessed, and only technologies tested in studies with low risk of bias were considered reliable. From 23 studies included—swine (13), poultry (6), and bovine (4) —only three complied with our reliability criteria; however, two of these were considered to have a high risk of bias. Thus, only one swine technology fully fit our criteria. Future studies should include field tests and use previously validated reference tests to assess technology’s performance. In conclusion, relying completely on PLF for monitoring respiratory diseases is still a challenge, though several technologies are promising, having high performance in field tests.

This paper is concerned with the design problem of causal gain-scheduled output feedback controllers for linear parameter-varying systems using parameter-dependent Lyapunov functions. This research topic has already been addressed by several researchers, and several effective methods have been correspondingly proposed in terms of parametrically dependent matrix inequalities. This paper addresses the dual formulation of one of the methods, and successfully derives the counterpart result in continuous-time case but points out the intractability of deriving the counterpart result in discrete-time case. It is also shown, in discrete-time case, that the intractability disappears and a design method similar to an existing method is successfully derived if the causality with respect to scheduling parameters is abandoned, namely, if one-step ahead scheduling parameters are available. A toy example is introduced to confirm that, in continuous-time case, the derived dual formulation gives the same performance as the previously proposed method for the dual state-space representation of the example.

A new device for conversion from 5G mobile wireless signals to optical signals, which is suitable for a passive wireless receiver in uplinks of 5G mobile front-haul in dense user environments, and a 5G-band sensor for precise antenna measurement, has been developed utilizing an array of antenna-coupled electrodes integrated on a high-speed LiNbO3 electro-optic (EO) modulator. The 5G wireless signal conversion and the high-speed data transfer over a silica optical fiber link for high-definition (HD) video streaming were demonstrated successfully using the fabricated device operating in the 28 GHz-band.

Interactions between energetic particles (EPs), an internal kink mode, and other magnetohydrodynamic (MHD) instabilities in the inductive scenario of JT-60SA (scenario $\#$ 2) are simulated with MEGA, a global EP–MHD hybrid code. For this scenario, it was predicted by TOPICS, an integrated transport code that the internal kink mode can be unstable and the sawtooth relaxation results in a flat safety factor ( q ) profile with q ≈ 1 for $r/a \unicode{x2A7D} 0.6$ . In this equilibrium, it is found in the simulation results that the stability of the internal kink mode depends strongly on the bulk plasma pressure gradient ( $\nabla P_\mathrm{b}$ ). In the n = 1 simulations where the toroidal mode number is restricted to n = 0 and 1, the pressure-driven internal kink mode is dominant. In the presence of co-passing EPs generated by the negative-ion-based neutral beam (NB), these EPs transfer energy to the internal kink mode; however, the EP driving rate ( $\gamma_\mathrm{h}$ ) is much lower than the driving rate from the bulk plasma pressure gradient ( $\gamma_\mathrm{P}$ ). The mode’s frequency is less than 1 kHz because the toroidal orbit frequency ( ω _φ ) and poloidal orbit frequency ( ω _θ ) of the co-passing EPs are approximately equal within the q = 1 surfaces. This mode affects the EP and bulk plasma pressure redistributions. The feasibility of stabilizing the internal kink mode using trapped EPs is also investigated. It is found that the trapped EPs with energy 85 keV generated by the positive-ion-based NBs cannot stabilize the internal kink mode. Stabilization is observed when the injection energy is greater than 500 keV. In the multi- n simulations, where $n\unicode{x2A7D} 8$ modes are retained, the most unstable modes are high n interchange modes with poloidal number m = n whose linear growth rates exceed that of the pressure-driven internal kink mode observed in the n = 1 simulations. The overlapping of these modes creates a stochastic magnetic field, leading to stronger EP and bulk plasma pressure redistributions than those observed in the n = 1 simulations. During the nonlinear phase, the transition from the high m = n modes to the low m = n modes is observed where the dominant mode is the $m/n = 1/1$ mode with an internal kink-like structure. These low m = n modes are generated by the nonlinear coupling of the high m = n modes. The EP kinetic effect has a minor contribution to the dynamics of these nonlinearly generated m = n modes.

Introdução: A pandemia mundial causada pelo novo coronavírus SARS-CoV-2 (COVID-19) teve impacto importante nos serviços de hemoterapia. O início da pandemia levou a diminuição tanto da demanda transfusional quanto do total de doações de sangue. Entretanto, a manutenção de estoque adequado de hemocomponentes tornou-se crítica quando o aumento no total de unidades transfundidas não ocorreu também no número de doações de sangue. A percepção de risco potencial de contaminação pela COVID-19 levou a uma queda significativa nas doações de sangue. A pandemia teve papel crucial no crescimento exponencial da telemedicina, com o sancionamento, em caráter emergencial, de novas leis regulatórias e expansão das áreas de atuação. No Brasil, a triagem clínica do candidato a doação de sangue é feita de forma presencial, face-a-face. Historicamente, o índice de inaptidão clínica no nosso serviço varia de 18% a 23%. A entrevista feita a distância (teletriagem) evitaria o deslocamento do doador com inaptidão clínica até o banco de sangue. A teletriagem, além de ser uma conveniência bem-vinda ao doador, traz a possibilidade de diminuir o tempo de sua permanência no banco de sangue. Objetivos: Avaliar a viabilidade do uso da teletriagem (triagem por telemedicina) como alternativa a triagem presencial na seleção de doadores de sangue. Materiais e métodos: A data e o horário do atendimento virtual por videoconferência foram agendados pelo candidato a doação e ele foi orientado sobre a necessidade de estar em local com privacidade durante a entrevista clínica. O questionário foi aplicado pelo profissional do banco de sangue também num local com privacidade. O candidato com inaptidão clínica não necessitaria comparecer ao banco de sangue e o candidato apto deveria realizar a sua doação até 7 dias após a teletriagem. No dia da doação, um questionário clínico reduzido foi aplicado, além da aferição dos sinais vitais e determinação do nível de hemoglobina para confirmar a aptidão para a doação. Resultados: Um total de 288 agendamentos para teletriagem foi feito de junho de 2020 a julho de 2021, sendo 153 candidatos a doação de sangue (ST) e 135 a doação de plaquetas por aférese (PQA). A teletriagem não foi realizada por problemas técnicos (áudio ou vídeo) ou ausência de 35 (12%) candidatos. Ao término da triagem clínica, 213/253 (84%) candidatos foram considerados aptos e 40/253 (16%) inaptos a doação. Neste último grupo, 36 eram candidatos a doação de ST e 4 de PQA. Dentre os 213 candidatos aptos pela teletriagem, 190 (89%) compareceram ao banco de sangue e 184 realizaram a doação. O tempo na triagem clínica no dia da doação teve redução de 36% para o doador de ST e 42% para PQA. A experiência com a teletriagem foi considerada positiva e seria indicada por 90% dos participantes. Discussão: O índice de inaptidão entre os candidatos aprovados na teletriagem foi baixo, 6/190 (3%) quando comparado ao índice de 18–23% observado no nosso serviço com a triagem presencial. Portanto, a teletriagem se mostrou eficaz em identificar candidatos com inaptidão clínica e evitar o seu deslocamento até o banco de sangue. Além disso, houve redução no tempo de triagem clínica presencial, o que contribuiu para diminuir o tempo total de permanência do doador no banco de sangue. A taxa de não comparecimento dos candidatos considerados aptos na teletriagem foi de 11% e representa uma oportunidade de melhorar a conscientização do candidato à doação. Conclusão: A teletriagem pode ser uma alternativa viável e uma conveniência bem vinda ao candidato a doação para evitar deslocamento desnecessário e reduzir o tempo de permanência do doador no banco de sangue.

The Thr92Ala-Dio2 polymorphism has been associated with reduced cognition in 2-month-old male mice and increased risk for cognitive impairment and Alzheimer’s disease in African Americans. This has been attributed to reduced thyroid hormone (TH) signaling and endoplasmic reticulum (ER) stress in the brain. Here we studied the Thr92Ala-Dio2 mouse model and saw that older male mice (7–8-month-old) exhibited a more severe cognition impairment, which extended to different aspects of declarative and working memories. A similar phenotype was observed in 4–5-month-old female mice. There were no structural alterations in the prefrontal cortex (PFC) and hippocampus of the Thr92Ala-Dio2 mouse. Nonetheless, in both male and female PFC, there was an enrichment in genes associated with TH-dependent processes, ER stress, and Golgi apparatus, while in the hippocampus there was additional enrichment in genes associated with inflammation and apoptosis. Reduced TH signaling remains a key mechanism of disease given that short-term treatment with L-T3 rescued the cognitive phenotype observed in males and females. We conclude that in mice, age is an additional risk factor for cognitive impairment associated with the Thr92Ala-Dio2 polymorphism. In addition to reduced TH signaling, ER-stress, and involvement of the Golgi apparatus, hippocampal inflammation and apoptosis were identified as potentially important mechanisms of a disease.

We observed a distinct peak in the Λp invariant mass spectrum of He3(K−,Λp)n, well below mK+2mp, i.e., the mass threshold of the K− to be bound to two protons. By selecting a relatively large momentum-transfer region q=350∼650 MeV/c, one can kinematically separate the peak from the quasi-free process, K‾N→K‾N followed by the non-resonant absorption by the two spectator-nucleons K‾NN→ΛN. We found that the simplest fit to the observed peak gives us a Breit–Wigner pole position at BKpp=47±3(stat.)−6+3(sys.) MeV having a width ΓKpp=115±7(stat.)−20+10(sys.) MeV, and the S-wave Gaussian reaction form-factor parameter QKpp=381±14(stat.)−0+57(sys.) MeV/c, as a new form of the nuclear bound system with strangeness – “K−pp”. Keywords: Kaon, Strangeness, Mesonic nuclear bound state

Coherent double neutral-pion photoproduction on the deuteron, γd→π0π0d, has been experimentally studied at incident photon energies ranging from 0.75 to 1.15 GeV. The total cross section as a function of the γd center-of-mass energy shows resonance-like behavior, which peaks at approximately 2.47 and 2.63 GeV. The measured angular distribution of deuteron emission is rather flat, which cannot be reproduced by the kinematics of quasi-free π0π0 production with deuteron coalescence. In π0d invariant-mass distributions, a clear peak is observed at 2.14±0.01 GeV/c2 with a width of 0.09±0.01 GeV/c2. The spin-parity of this state is restricted to 1+, 2+ or 3− from the angular distributions of the two π0s. The present work shows strong evidence for the existence of an isovector dibaryon resonance with a mass of 2.14 GeV/c2. The 2+ assignment is consistent with the theoretically predicted D12 state, and also with the energy dependence of the πd partial-wave amplitude P23 for the π±d→π±d and π+d→pp reactions. Keywords: Coherent meson photoproduction, Dibaryon resonance

A planetary-scale streak structure in the Venusian lower-cloud layer was observed by the Akatsuki orbiter. Here the authors present numerical simulations that reproduce such structure and reveal that a low-stability layer, which induces baroclinic disturbances, is essential for its formation.

We report the sol–gel synthesis of Cu2V2O7 fine particles, in which some of the constituent Cu is replaced with other elements. The sintered body of Zn substituted β-Cu1.8Zn0.2V2O7 shows a large negative thermal expansion (NTE) over a wide temperature range due to microstructural effects peculiar to a ceramic body. Using the sol–gel method, we successfully produced β-Cu1.8Zn0.2V2O7 ceramic fine particles that retain the same level of thermal expansion suppression capabilities as the bulk with a size of about 1 μm. We also succeeded in performing rare earth metal (Ce, Sm, Yb) substitutions, which might be a clue for improving NTE performance. These achievements provide particulate filler for thermal expansion control of a micrometer region, which has been earnestly sought in many fields of technology.

Fine particulate matter (PM2.5) samples collected at Mount (Mt.) Tai in the North China Plain during summer 2014 were analyzed for dicarboxylic acids and related compounds (oxocarboxylic acids and α-dicarbonyls) (DCRCs). The total concentration of DCRCs was 1050±580 and 1040±490 ng m−3 during the day and night, respectively. Although these concentrations were about 2 times lower than similar measurements in 2006, the concentrations reported here were about 1–13 times higher than previous measurements in other major cities in the world. Molecular distributions of DCRCs revealed that oxalic acid (C2) was the dominant species (50 %), followed by succinic acid (C4) (12 %) and malonic acid (C3) (8 %). WRF modeling revealed that Mt. Tai was mostly in the free troposphere during the campaign and long-range transport was a major factor governing the distributions of the measured compounds at Mt. Tai. A majority of the samples (79 %) had comparable concentrations during the day and night, with their day–night concentration ratios between 0.9 and 1.1. Multi-day transport was considered an important reason for the similar concentrations. Correlation analyses of DCRCs and their gas precursors and between C2 and sulfate indicated precursor emissions and aqueous-phase oxidations during long-range transport also likely play an important role, especially during the night. Source identification indicated that anthropogenic activities followed by photochemical aging accounted for about 60 % of the total variance and were the dominant source at Mt. Tai. However, biomass burning was only important during the first half of the measurement period. Measurements of potassium (K+) and DCRCs were about 2 times higher than those from the second half of the measurement period. The concentration of levoglucosan, a biomass burning tracer, decreased by about 80 % between 2006 and 2014, indicating that biomass burning may have decreased between 2006 and 2014.

Abstract The existence of lightning discharges in the Venus atmosphere has been controversial for more than 30 years, with many positive and negative reports published. The lightning and airglow camera (LAC) onboard the Venus orbiter, Akatsuki, was designed to observe the light curve of possible flashes at a sufficiently high sampling rate to discriminate lightning from other sources and can thereby perform a more definitive search for optical emissions. Akatsuki arrived at Venus during December 2016, 5 years following its launch. The initial operations of LAC through November 2016 have included a progressive increase in the high voltage applied to the avalanche photodiode detector. LAC began lightning survey observations in December 2016. It was confirmed that the operational high voltage was achieved and that the triggering system functions correctly. LAC lightning search observations are planned to continue for several years.

We performed a feasibility study of constraining the vertical profile of the tropospheric ozone by using a synergetic retrieval method on multiple spectra, i.e., ultraviolet (UV), thermal infrared (TIR), and microwave (MW) ranges, measured from space. This work provides, for the first time, a quantitative evaluation of the retrieval sensitivity of the tropospheric ozone by adding the MW measurement to the UV and TIR measurements. Two observation points in East Asia (one in an urban area and one in an ocean area) and two observation times (one during summer and one during winter) were assumed. Geometry of line of sight was nadir down-looking for the UV and TIR measurements, and limb sounding for the MW measurement. The retrieval sensitivities of the ozone profiles in the upper troposphere (UT), middle troposphere (MT), and lowermost troposphere (LMT) were estimated using the degree of freedom for signal (DFS), the pressure of maximum sensitivity, reduction rate of error from the a priori error, and the averaging kernel matrix, derived based on the optimal estimation method. The measurement noise levels were assumed to be the same as those for currently available instruments. The weighting functions for the UV, TIR, and MW ranges were calculated using the SCIATRAN radiative transfer model, the Line-By-Line Radiative Transfer Model (LBLRTM), and the Advanced Model for Atmospheric Terahertz Radiation Analysis and Simulation (AMATERASU), respectively. The DFS value was increased by approximately 96, 23, and 30 % by adding the MW measurements to the combination of UV and TIR measurements in the UT, MT, and LMT regions, respectively. The MW measurement increased the DFS value of the LMT ozone; nevertheless, the MW measurement alone has no sensitivity to the LMT ozone. The pressure of maximum sensitivity value for the LMT ozone was also increased by adding the MW measurement. These findings indicate that better information on LMT ozone can be obtained by adding constraints on the UT and MT ozone from the MW measurement. The results of this study are applicable to the upcoming air-quality monitoring missions, APOLLO, GMAP-Asia, and uvSCOPE.

Abstract The ultraviolet imager (UVI) has been developed for the Akatsuki spacecraft (Venus Climate Orbiter mission). The UVI takes ultraviolet (UV) images of the solar radiation reflected by the Venusian clouds with narrow bandpass filters centered at the 283 and 365 nm wavelengths. There are absorption bands of SO2 and unknown absorbers in these wavelength regions. The UV images provide the spatial distribution of SO2 and the unknown absorber around cloud top altitudes. The images also allow us to understand the cloud top morphologies and haze properties. Nominal sequential images with 2-h intervals are used to understand the dynamics of the Venusian atmosphere by estimating the wind vectors at the cloud top altitude, as well as the mass transportation of UV absorbers. The UVI is equipped with off-axial catadioptric optics, two bandpass filters, a diffuser installed in a filter wheel moving with a step motor, and a high sensitivity charge-coupled device with UV coating. The UVI images have spatial resolutions ranging from 200 m to 86 km at sub-spacecraft points. The UVI has been kept in good condition during the extended interplanetary cruise by carefully designed operations that have maintained its temperature maintenance and avoided solar radiation damage. The images have signal-to-noise ratios of over 100 after onboard desmear processing.

Abstract Since insertion into orbit on December 7, 2015, the Akatsuki orbiter has returned global images of Venus from its four imaging cameras at eleven discrete wavelengths from ultraviolet (283 and 365 nm) and near infrared (0.9–2.3 µm), to the thermal infrared (8–12 µm) from a near-equatorial orbit. The Venus Express and Pioneer Venus Orbiter missions have also monitored the planet for long periods but from polar or near-polar orbits. The wavelength coverage and views of the planet also differ for all three missions. In reflected light, the images reveal features seen near the cloud tops (~ 70 km altitude), whereas in the near-infrared images of the nightside, features seen are at mid- to lower cloud levels (~ 48–60 km altitude). The dayside cloud cover imaged at the ultraviolet wavelengths shows morphologies similar to what was observed from Mariner 10, Pioneer Venus, Galileo, Venus Express and MESSENGER. The daytime images at 0.9 and 2.02 µm also reveal some interesting features which bear similarity to the ultraviolet images. The nighttime images at 1.74, 2.26 and 2.32 µm and at 8–12 µm reveal features not seen before and show new details of the nightside including narrow wavy ribbons, curved string-like features, long-scale waves, long dark streaks, isolated bright spots, sharp boundaries and even mesoscale vortices. Some features previously seen such as circum-equatorial belts (CEBs) and occasional areal brightenings at ultraviolet (seen in Venus Express observations) of the cloud cover at ultraviolet wavelengths have not been observed thus far. Evidence for the hemispheric vortex organization of the global circulation can be seen at all wavelengths on the day- and nightsides. Akatsuki images reveal new and puzzling morphology of the complex nightside cloud cover. The cloud morphologies provide some clues to the processes occurring in the atmosphere and are thus, a key diagnostic tool when quantitative dynamical analysis is not feasible due to insufficient information.

Abstract The status and initial products of the 1-μm camera onboard the Akatsuki mission to Venus are presented. After the successful retrial of Venus’ orbit insertion on Dec. 2015 (5 years after the failure in Dec. 2010), and after a long cruise under intense radiation, damage in the detector seems small and fortunately insignificant in the final quality of the images. More than 600 dayside images have been obtained since the beginning of regular operation on Apr. 2016 although nightside images are less numerous (about 150 in total at three wavelengths) due to the light scattered from the bright dayside. However, data acquisition stopped after December 07, 2016, due to malfunction of the electronics and has not been resumed since then. The 0.90-µm dayside images are of sufficient quality for the cloud-tracking procedure to retrieve wind field in the cloud region. The results appear to be similar to those reported by previous 1-μm imaging by Galileo and Venus Express. The representative altitude sampled for such dayside images is estimated to be 51–55 km. Also, the quality of the nightside 1.01-µm images is sufficient for a search for active volcanism, since interference due to cloud inhomogeneity appears to be insignificant. The quality of the 0.97-µm images may be insufficient to achieve the expected spatial resolution for the near-surface H2O mixing ratio retrievals.

Abstract We provide an overview of data products from observations by the Japanese Venus Climate Orbiter, Akatsuki, and describe the definition and content of each data-processing level. Levels 1 and 2 consist of non-calibrated and calibrated radiance (or brightness temperature), respectively, as well as geometry information (e.g., illumination angles). Level 3 data are global-grid data in the regular longitude–latitude coordinate system, produced from the contents of Level 2. Non-negligible errors in navigational data and instrumental alignment can result in serious errors in the geometry calculations. Such errors cause mismapping of the data and lead to inconsistencies between radiances and illumination angles, along with errors in cloud-motion vectors. Thus, we carefully correct the boresight pointing of each camera by fitting an ellipse to the observed Venusian limb to provide improved longitude–latitude maps for Level 3 products, if possible. The accuracy of the pointing correction is also estimated statistically by simulating observed limb distributions. The results show that our algorithm successfully corrects instrumental pointing and will enable a variety of studies on the Venusian atmosphere using Akatsuki data.

Abstract The first year (December 2015 to November 2016) of IR2 after Akatsuki’s successful insertion to an elongated elliptical orbit around Venus is reported with performance evaluation and results of data acquisition. The single-stage Stirling-cycle cryo-cooler of IR2 has been operated with various driving voltages to achieve the best possible cooling under the given thermal environment. A total of 3091 images of Venus (1420 dayside images at 2.02 μm and 1671 night-side images at 1.735, 2.26, and 2.32 μm) were acquired in this period. Additionally, 159 images, including images of stars for calibration and dark images for the evaluation of noise levels, were captured. Low-frequency flat images (not available in pre-launch calibration data) have been constructed using the images of Venus acquired from near the pericenter to establish the procedure to correct for the IR2 flat-field response. It was noticed that multiple reflections of infrared light in the PtSi detector caused a weak but extended tail of the point-spread function (PSF), contaminating the night-side disk of Venus with light from the much brighter dayside crescent. This necessitated the construction of an empirical PSF to remove this contamination and also to improve the dayside data by deconvolution, and this work is also discussed. Detailed astrometry is performed on star-field images in the H-band (1.65 μm), hereby confirming that the geometrical distortion of IR2 images is negligible.

Abstract The Venus Climate Orbiter Akatsuki arrived at Venus in December 2015, and the Longwave Infrared Camera (LIR) onboard the spacecraft started making observations. LIR has acquired more than 8000 images during the first two Venusian years since orbit insertion without any serious faults. However, brightness temperature derived from LIR images contained an unexpected bias that related not to natural phenomena but to a thermal condition of the instrument. The bias could be partially eliminated by keeping the power supply unit for LIR always active, while the residual bias was simply correlated with the baffle temperature. Therefore, deep-space images were acquired at different baffle temperatures on orbit, and a reference table for eliminating the bias from images was prepared. In the corrected images, the brightness temperature was ~ 230 K at the center of the Venus disk, where the effect of limb darkening is negligible. The result is independent of the baffle temperature and consistent with the results of previous studies. Later, a laboratory experiment with the proto model of LIR showed that when the germanium (Ge) lens was heated, its actual temperature was slightly higher than the temperature measured by a thermal sensor attached to the lens holder. The experiment confirmed that transitory baffle heating accounted for the background bias found in the brightness temperature observed by LIR.

Abstract After the arrival of Akatsuki spacecraft of Japan Aerospace Exploration Agency at Venus in December 2015, the radio occultation experiment, termed RS (Radio Science), obtained 19 vertical profiles of the Venusian atmosphere by April 2017. An onboard ultra-stable oscillator is used to generate stable X-band downlink signals needed for the experiment. The quantities to be retrieved are the atmospheric pressure, the temperature, the sulfuric acid vapor mixing ratio, and the electron density. Temperature profiles were successfully obtained down to ~ 38 km altitude and show distinct atmospheric structures depending on the altitude. The overall structure is close to the previous observations, suggesting a remarkable stability of the thermal structure. Local time-dependent features are seen within and above the clouds, which is located around 48–70 km altitude. The H2SO4 vapor density roughly follows the saturation curve at cloud heights, suggesting equilibrium with cloud particles. The ionospheric electron density profiles are also successfully retrieved, showing distinct local time dependence. Akatsuki RS mainly probes the low and middle latitude regions thanks to the near-equatorial orbit in contrast to the previous radio occultation experiments using polar orbiters. Studies based on combined analyses of RS and optical imaging data are ongoing. Graphical abstract .

The total cross sections were measured for coherent double neutral-pion photoproduction on the deuteron at incident energies below 0.9 GeV for the first time. No clear resonance-like behavior is observed in the excitation function for Wγd=2.38–2.61 GeV, where the d⁎(2380) dibaryon resonance observed at COSY is expected to appear. The measured excitation function is consistent with the existing theoretical calculation for this reaction. The upper limit of the total cross section is found to be 0.034 μb for the dibaryon resonance at Wγd=2.37 GeV (90% confidence level) in the γd→π0π0d reaction.