ALBERT

Description: Experimental and clinical studies have shown that the technique of deep brain stimulation (DBS) plays a potential role in the regulation of Alzheimer’s disease (AD), yet it still desires for ongoing studies including clinical trials, theoretical approach and action mechanism. In this work, we develop a modified thalamo-cortico-thalamic (TCT) model associated with AD to explore the therapeutic effects of DBS on AD from the perspective of neurocomputation. First, the neuropathological state of AD resulting from synapse loss is mimicked by decreasing the synaptic connectivity strength from the Inter-Neurons (IN) neuron population to the Thalamic Relay Cells (TRC) neuron population. Under such AD condition, a specific deep brain stimulation voltage is then implanted into the neural nucleus of TRC in this TCT model. The symptom of AD is found significantly relieved by means of power spectrum analysis and nonlinear dynamical analysis. Furthermore, the therapeutic effects of DBS on AD are systematically examined in different parameter space of DBS. The results demonstrate that the controlling effect of DBS on AD can be efficient by appropriately tuning the key parameters of DBS including amplitude A, period P and duration D. This work highlights the critical role of thalamus stimulation for brain disease, and provides a theoretical basis for future experimental and clinical studies in treating AD.

Description: Accurate assessment of anthropogenic carbon dioxide (CO2) emissions and their redistribution among the atmosphere, ocean, and terrestrial biosphere in a changing climate is critical to better understand the global carbon cycle, support the development of climate policies, and project future climate change. Here we describe and synthesize data sets and methodology to quantify the five major components of the global carbon budget and their uncertainties. Fossil CO2 emissions (EFOS) are based on energy statistics and cement production data, while emissions from land-use change (ELUC), mainly deforestation, are based on land-use and land-use change data and bookkeeping models. Atmospheric CO2 concentration is measured directly, and its growth rate (GATM) is computed from the annual changes in concentration. The ocean CO2 sink (SOCEAN) is estimated with global ocean biogeochemistry models and observation-based fCO2 products. The terrestrial CO2 sink (SLAND) is estimated with dynamic global vegetation models. Additional lines of evidence on land and ocean sinks are provided by atmospheric inversions, atmospheric oxygen measurements, and Earth system models. The resulting carbon budget imbalance (BIM), the difference between the estimated total emissions and the estimated changes in the atmosphere, ocean, and terrestrial biosphere, is a measure of imperfect data and incomplete understanding of the contemporary carbon cycle. All uncertainties are reported as ±1σ. For the year 2022, EFOS increased by 0.9 % relative to 2021, with fossil emissions at 9.9±0.5 Gt C yr−1 (10.2±0.5 Gt C yr−1 when the cement carbonation sink is not included), and ELUC was 1.2±0.7 Gt C yr−1, for a total anthropogenic CO2 emission (including the cement carbonation sink) of 11.1±0.8 Gt C yr−1 (40.7±3.2 Gt CO2 yr−1). Also, for 2022, GATM was 4.6±0.2 Gt C yr−1 (2.18±0.1 ppm yr−1; ppm denotes parts per million), SOCEAN was 2.8±0.4 Gt C yr−1, and SLAND was 3.8±0.8 Gt C yr−1, with a BIM of −0.1 Gt C yr−1 (i.e. total estimated sources marginally too low or sinks marginally too high). The global atmospheric CO2 concentration averaged over 2022 reached 417.1±0.1 ppm. Preliminary data for 2023 suggest an increase in EFOS relative to 2022 of +1.1 % (0.0 % to 2.1 %) globally and atmospheric CO2 concentration reaching 419.3 ppm, 51 % above the pre-industrial level (around 278 ppm in 1750). Overall, the mean of and trend in the components of the global carbon budget are consistently estimated over the period 1959–2022, with a near-zero overall budget imbalance, although discrepancies of up to around 1 Gt C yr−1 persist for the representation of annual to semi-decadal variability in CO2 fluxes. Comparison of estimates from multiple approaches and observations shows the following: (1) a persistent large uncertainty in the estimate of land-use changes emissions, (2) a low agreement between the different methods on the magnitude of the land CO2 flux in the northern extra-tropics, and (3) a discrepancy between the different methods on the strength of the ocean sink over the last decade.

Description: The typical hallmark of electroencephalogram (EEG) in Alzheimer’s disease (AD) is a slowing of rhythms and perturbations in synchrony. However, the mechanism of AD electrophysiological abnormalities is still ambiguous. Synapse deficiency has been considered as an evident neuropathological change in AD that is closely associated with cognitive decline. The main purpose of this work is to explore how synapse deficiency in AD affects these electrophysiological features using neural computational techniques. First, based on the Diffusion Tensor Imaging data, a connectivity matrix of a structural brain network is constructed by means of a pipeline toolbox called PANDA. Using this data-driven connectivity matrix, a cortical network model with 90 cortical areas is then be built in which each cortical area is modeled by a neuron mass model. Subsequently, by reducing the synaptic strength parameter to mimic synapse deficiency in AD, our results show that the synapse deficiency does not only cause a leftward shift of the dominant frequency, but also induces a decrease in the alpha rhythm and an increase in the theta rhythm. Further, the influence of synapse deficiency on phase synchrony is investigated by the phase lag index (PLI). When the synaptic strength parameter is reduced, the alpha-band PLI decreases and theta-band PLI increases. Moreover, a statistical analysis of the differences between the simulated AD and healthy control (HC) in terms of synchronization and rhythms is performed. The results demonstrate that there are significant differences between simulated AD and HC groups. All the above simulation results are consistent with the EEG changes of AD in the physiological experiments. Finally, a strong statistical correlation between PLI and relative power is revealed using Pearson’s correlation analysis. This study reveals a close relationship between synapse deficiency and electrophysiological abnormalities in AD, which may provide new insight for the early diagnosis of AD.

Description: We present an attenuation model for midperiod Rayleigh waves in Central Asia and surrounding regions. This model is defined by maps of attenuation coefficient across the region of study in the period band 14–24 s. The model is constructed to characterize the regional variations in attenuation of seismic waves in the crust, which are related to the tectonic history of the studied territory, to calibrate the regional surface-wave magnitude scale, and to extend the teleseismic 'surface-wave magnitude – body wave magnitude' (Ms-mb) discriminant to regional distances. The construction of the model proceeds in three stages. The first stage in model construction is the measurement of Rayleigh wave spectral amplitudes. We collected and processed waveform data for 200 earthquakes occurring from 2003 to 2006 inside and around Eurasia, and used records of about 135 broadband permanent and temporary stations. This data set provided a sufficient number of spectral amplitude measurements between 14 and 24 s periods for the construction of two–dimensional tomographic maps of attenuation coefficients. At the second stage of the work, the integral of attenuation coefficients along given paths is estimated using both inter-station measurements and single-station measurements corrected for source and receiver terms. The third stage includes the refining of source parameters, recalculation of attenuation coefficient integrals after this refinement, grooming of resulting coefficients, and multistage tomographic inversion of the data. Tomographic maps for the set of periods from 14 to 24 s, which exhibit clear correlation with geology and tectonics of the territory under study, were obtained. Validation of these maps using the inter-station measurements confirms their accuracy in predicting the observations.

Description: The economic and human losses caused by drought are increasing in recent decades. It is very important to explore drought and understandthe propagation relationships between different drought for drought mitigation, early warning and ecological security.In recent years, many scholars have devoted themselves to isolating the impact of human activities on the drought propagation process, but the methods used are poorly generalized or have harsh application conditions. As the most advanced hydrological model in the world, PCR-GLOBWB can subdivide and quantify the impact of human activities on hydrological processes. Therefore, we used the PCR-GLOBWB hydrological model to simulate the terrestrial water cycle process under human and natural scenarios (1961-2020) in the Yellow River Basin (YRB) respectively, and the effects of human activities on hydrological drought and drought propagation were evaluated comprehensively. The results show that human activities have exacerbated the hydrological drought in YRB (Variable increase in frequency, magnitude and duration). In the YRB, the propagation rate (PR) of meteorological drought to hydrological drought ranges from 45-75%, and the PT is 6-23 months. The PR decreased with percentage 1-60% due to human activities, and PT decreased (1-13 month).Furthermore, human activities have intensified the extent of the meteorological drought propagation to hydrological drought in the YRB. This study has important implications for drought damage mitigation and developing drought early warning measures.

Description: A constellation of radiation belts survey (CORBES) program is proposed by the Sub-Group on Radiation Belt (SGRB) of TGCSS, COSPAR, which is in pursuit of the goal of SGRB, focusing on the implementation of a Small/CubeSats constellation mission for radiation belt exploration. Basing on a general review of the status quo of research on the Earth's radiation belts dynamics and the unresolved scientific issues, the scientific object and observation requirements of CORBES are proposed. The CORBES program is expected to have a constellation of 10-plus small/ CubeSats to take an ultra-fast survey of the Earth’s radiation belt. The general science goal for CORBES is to investigate two groups of physical processes related to the radiation belts: wave-particle interactions and radial transport. This program is an international multilateral cooperation mission, an open and sharing data policy will be implemented. The data set of observations will be shared within the contributors of the constellation and the broad research community at large, then would be of great use for comprehensively understanding the dynamics of magnetospheric energetic populations and developing more standard models of the Earth’s radiation belts. Furthermore, from the application perspective, the ultra-fast survey of the radiation belt could serve as an important facility for monitoring space weather of the Earth as well.

Description: Surface snow samples were collected daily, at several sites representing distinct environments: sea ice, inland close to sea level, and a hilltop ~600 m above sea level (asl), from a Canadian high Arctic location at Eureka, Nunavut (80°N, 86°W) from the end of February to the end of March in 2018 and 2019. Snow samples were under ionic and salinity analysis. The aim of this study is to explore the role of snowpack in polar spring boundary layer chemistry, especially as a direct source of reactive bromine (BrO〈sub〉X〈/sub〉=BrO+Br) and nitrogen (NO〈sub〉X〈/sub〉=NO+NO〈sub〉2〈/sub〉). We find that surface snow bromide at sea level is significantly enriched, indicating a net sink of atmospheric bromine. Both surface snow bromide and nitrate at sea level have an increasing trend over the measurement time period. Using these trends, we derive an integrated net deposition flux of bromide of 1.01×10〈sup〉7〈/sup〉 molecules cm〈sup〉-2〈/sup〉 s〈sup〉-1〈/sup〉 and of nitrate of 2.6×10〈sup〉8〈/sup〉 molecules cm〈sup〉-2〈/sup〉 s〈sup〉-1〈/sup〉. In addition, nitrate and bromide in the morning samples are significantly higher than the afternoon samples, indicating a strong photochemistry effect, however the bromide loss rate is smaller than the nitrate loss rate by more than an order of magnitude. Also, surface snow nitrate and bromide at inland sites are significantly correlated (R=0.48-0.76), with a [NO〈sub〉3〈/sub〉〈sup〉-〈/sup〉]/[Br〈sup〉-〈/sup〉] ratio of 4-7 indicating a possible acceleration effect of reactive bromine in atmospheric NO〈sub〉X〈/sub〉-to-nitrate conversion. This is the first time we see such an effect from snow chemistry data obtained with a sampling frequency as short as one day.

Description: Oceanic frontal zone is key region of the oceanic feedback to the atmosphere in the extratropics. The oceanic frontal zone in the wintertime North Pacific exhibits a unique double fronts structure, with a subtropical oceanic frontal zone (STFZ) and a subarctic frontal zone (SAFZ). The feedback of the variability of the two oceanic frontal zones in the wintertime North Pacific on the atmosphere are investigated using daily observational data. The anomalies of the STFZ and SAFZ are both associated with the dipolar SST anomalies with cold (warm) anomalies in the north (south). Following the peak of the STFZ and SAFZ, the dipolar SST anomalies can both maintain almost 30 days. For the STFZ, the anomalous upward surface heat flux in the south of the STFZ indicates the warming effect of the warm SST anomalies on the overlying atmosphere, resulting in the positive anomalies of the near-surface air temperature. The combined effects of the warm anomalies of the near-surface air temperature in the south of the STFZ and cold anomalies of the near-surface air temperature induced by the atmospheric advection result in the enhancement of the near-surface baroclinicity over the STFZ. However, with weak and insignificant anomalous upward surface heat flux, we find that the feedback of the SAFZ on the atmosphere is much weaker. The weak feedback is attributed to downstream of the anomalous atmospheric circulations associated with the SAFZ, which results in the weak air-sea humidity difference and wind speed.

Description: The acidity of sea ice and sea ice aerosols plays a key role in the reactivity of the cryosphere, leading to or mediating processes such as the oxidation of bromine, which results in tropospheric ozone depletion events. We performed laboratory experiments to assess the acidity and subsequently used an environmental scanning electron microscope to observe the particles that emanate from the sublimating sea ices. For the acidity assessment, we propose a spectrophotometric method based on sulfonephthalein indicators employed in the frozen state. The diffuse reflectance UV-Vis approach thus allows estimating the local acidity at the level of molecular interactions and at environmentally relevant temperatures. Our results show a strong freezing-induced acidity increase in sea water, especially as regards solutions of low salinity. Importantly, the microscopic observation of sea ice sublimation revealed a major dependence of the temperature and concentration on the emanating aerosol-sized salt particles. In this context, the sublimation temperature of the ice is a dominant physical factor to determine the size of the residua: Below −20 °C, micron-sized pieces of salt emerge, whereas above this temperature large chunks of salt are detected. Concentration also plays a role in particle size distribution: Micron-sized particles are observed exclusively at salinities below 3.5 psu, while below 0.085 psu particles with a median smaller than 6 μm arise from sea ices at any subzero temperature.Generally, we relate our findings to the production of the polar atmospheric sea salt aerosols and acid-catalyzed reactivity reactions (e.g., photochemical bromine recycling).