Abstract. Long-term trends in downwelling solar irradiance and associated climatic factors over China are studied in the paper. Decreasing trends in global and direct radiation are observed over much of China. The largest decrease occurs in South and East China (east of about 100 • E and south of about 40 • N). The spatial pattern of observed trends in diffuse irradiance is complex and inhomogeneous. An intriguing aspect of trends in global and direct irradiance is the rather abrupt decrease in annual and seasonal mean values from 1978 onward. The decreasing trends in solar radiation in China did not persist into the 1990s. The spatial and temporal patterns of trends in sunshine duration are consistent with that of global and direct irradiance. A decreasing trend in rainy days is observed over much of China, which is in agreement with the secular trend in cloud amount. The fact that trends in cloud amount and solar radiation are quite similar suggests that the cloud amount is not the primary cause for the decrease in solar radiation. Visibility in the eastern part of China has deteriorated heavily as a result of the rapid increase in aerosol loading. The statistical analysis showed that atmospheric transmission under clear conditions decreased rapidly. These facts suggest that the rapid increase in aerosol loading should be one of the principle causes for the decrease in solar radiation. The observed diurnal temperature range decreases remarkably in China, which is closely related to the increase in aerosols. The effects of anthropogenic air pollutants on climate should be further studied and included in the simulation of climate and projection of climate scenario.

[1] Thirty-three months of aerosol data in Beijing are presented in this paper. Aerosol optical thickness (AOT) increases from January to June and then decreases gradually. However, airborne particulate matter with diameter less than 10 mm (PM 10 ) concentration exhibits higher values in winter and spring and lower concentration in summer. For the same PM 10 concentration, AOT in summer is approximately two, three, and four times that in autumn, winter, and spring, respectively. AOT increases persistently during daytime, and the diurnal variation varies from about 15% in summer to about 45% in winter. The seasonal and diurnal variation of AOT is quite different from that of surface particle concentration. This is partly attributed to the variation of atmospheric mixing layer height. Aerosol volume concentrations increase with AOT by nearly identical magnitude for fine and coarse mode except in spring. The volume concentration of coarse mode in spring increases by a magnitude of more than two times that derived in remaining seasons. Aerosol fine mode radius increases with AOT, whereas coarse mode radius keeps relatively invariable with AOT. Mean aerosol single-scattering albedo at 440 nm is about 0.90 and decreases slightly with wavelength. Aerosol single-scattering albedos increase and their spectral dependence reverses during dust periods. Aerosol size and absorption in Beijing are close to results derived in Mexico City and Kanpur, but they are quite different from those in Maryland and Paris. Therefore different urban aerosol models should be created and used in satellite remote sensing in different urban regions.

Low-intensity transcranial ultrasound (TUS) can non-invasively modulate human neural activity. We investigated how different fundamental sonication parameters influence the effects of TUS on the motor cortex (M1) of 16 healthy subjects by probing cortico-cortical excitability and behaviour. A low-intensity 500 kHz TUS transducer was coupled to a transcranial magnetic stimulation (TMS) coil. TMS was delivered 10 ms before the end of TUS to the left M1 hotspot of the first dorsal interosseous muscle. Varying acoustic parameters (pulse repetition frequency, duty cycle and sonication duration) on motor-evoked potential amplitude were examined. Paired-pulse measures of cortical inhibition and facilitation, and performance on a visuomotor task was also assessed. TUS safely suppressed TMS-elicited motor cortical activity, with longer sonication durations and shorter duty cycles when delivered in a blocked paradigm. TUS increased GABAA-mediated short-interval intracortical inhibition and decreased reaction time on visuomotor task but not when controlled with TUS at near-somatosensory threshold intensity.

No abstract

[1] Almost 4 years' worth of Aerosol Robotic Network (AERONET) data from Beijing are compiled with historic aerosol data obtained in a few years during the 1980s and 1990s. Aerosol properties, including aerosol optical depth (t), single scattering albedo (w) and asymmetry factor (g), show a large day-to-day variation and a distinct seasonal pattern. Aerosol loading is at its maximum during the summer and at its minimum during the winter. Aerosol loading frequently increases gradually from the background level to tens of times that of the background level a few days later, then quickly returns to the background level because of the passage of a weather system. Aerosol optical depth at 550 nm (t 550nm ) varies from about 0.28 in 1980 to about 0.68 in 2005, implying a significant increase in aerosol loading during the past 25 years. Historic w and g values are generally in agreement with AERONET data except that aerosol absorption during the winter is quite different. Aerosols induce significant changes in net solar radiation at the surface and at the top of the atmosphere (TOA). The aerosol direct radiative forcing (ADRF) at the surface varies from À17.2 W m À2 in January to À63.5 W m À2 in June and then to À18.5 W m À2 in December. ADRF at the TOA shows a similar seasonal variation to that at the surface, but the value is approximately 28-42% of the latter. A combination of high aerosol optical depth and strong aerosol absorption leads to significant ADRF in the atmosphere, ranging from 1.9 to 117.6 W m À2 , thus increasing atmospheric heating by 0.3 to 4.6 K/day. The long-term change in aerosol loading in China and its effects on climate and the environment deserve much attention.Citation: Xia, X., H. Chen, P. Goloub, W. Zhang, B. Chatenet, and P. Wang (2007), A compilation of aerosol optical properties and calculation of direct radiative forcing over an urban region in northern China,

There is now compelling evidence that selective stimulation of Aδ nociceptors eliciting first pain evokes robust responses in the primary somatosensory cortex (S1). In contrast, whether the C-fiber nociceptive input eliciting second pain has an organized projection to S1 remains an open question. Here, we recorded the electrocortical responses elicited by nociceptive-specific laser stimulation of the four limbs in 202 humans (both males and females, using EEG) and 12 freely moving rats (all males, using ECoG). Topographical analysis and source modeling revealed in both species, a clear gross somatotopy of the unmyelinated C-fiber input within the S1 contralateral to the stimulated side. In the human EEG, S1 activity could be isolated as an early-latency negative deflection (C-N1 wave peaking at 710–730 ms) after hand stimulation, but not after foot stimulation because of the spatiotemporal overlap with the subsequent large-amplitude supramodal vertex waves (C-N2/P2). In contrast, because of the across-species difference in the representation of the body surface within S1, S1 activity could be isolated in rat ECoG as a C-N1 after both forepaw and hindpaw stimulation. Finally, we observed a functional dissociation between the generators of the somatosensory-specific lateralized waves (C-N1) and those of the supramodal vertex waves (C-N2/P2), indicating that C-fiber unmyelinated input is processed in functionally distinct somatosensory and multimodal cortical areas. These findings demonstrated that C-fiber input conveys information about the spatial location of noxious stimulation across the body surface, a prerequisite for deploying an appropriate defensive motor repertoire.SIGNIFICANCE STATEMENT Unmyelinated C-fibers are the evolutionarily oldest peripheral afferents responding to noxious environmental stimuli. Whether C-fiber input conveys information about the spatial location of the noxious stimulation to the primary somatosensory cortex (S1) remains an open issue. In this study, C-fibers were activated by radiant heat stimuli delivered to different parts of the body in both humans and rodents while electrical brain activity was recorded. In both species, the C-fiber peripheral input projects to different parts of the contralateral S1, coherently with the representation of the body surface within this brain region. These findings demonstrate that C-fiber input conveys information about the spatial location of noxious stimulation across the body surface, a prerequisite for deploying an appropriate defensive motor repertoire.

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Background: Although conflicting findings abound, gender-related differences in olfactory identification have received continuous attention. To our best knowledge, no systematic and quantitative research has examined gender differences in olfaction identification at various stages of life. The present study aimed to find out if there is gender difference in human olfaction identification in different life stages. Methodology: Studies cited in the PubMed database were searched from its inception to August 2017 using the terms "olfact*" or "smell" and "gender" or "sex". The effect size of each comparison was calculated. 24 studies were included in this meta-analysis. Results: In this meta-analysis, we used Cohen's d to determine the effects sizes for the comparisons between women versus men among different groups. Its value was 0.18 (95% CI:-0.13 to 0.49) in Group A (age<18years), 0.62 (95% CI: 0.43 to 0.81) in Group B (age 18-50years), and 0.33 (95% CI:-0.01 to 0.66) in Group C. The effect was considered relatively small in Group A (age<18years) and Group C (age>50years), and a medium effect in Group B (age18-50 years). Moreover, a significant difference was only present in Group B (age18-50 years). Summarizing, the gender effect was only present in the group aged 18-50 years, in which women outperformed men significantly in odor identification. Conclusions: This meta-analytic review indicated that the gender differences only exist in young adults (age18-50 years), while absent in juveniles (age<18years) or an aged cohort (age >50years). Females outperformed males in the young adults.