Above-ground net primary production (ANPP) and precipitation-use efficiency (PUE) are key factors that can clarify the response of grassland ecosystem carbon and water cycles to ongoing climate change. The variations of ANPP and PUE were analysed based on longterm in situ observations of a species-rich alpine meadow in the north-eastern Qinghai-Tibetan Plateau from 1981 to 2010. ANPP and PUE increased markedly over time. ANPP was significantly controlled by postgrowing season length (from 1 September to the end of growing season in the previous year, R 2 = 0Á31, P < 0Á01). Regression trees showed that air temperature during October of the previous year played a predominant role in ANPP annual variations. Results indicated that a strong thermal-lagging effect on ANPP variations was present in the alpine meadow ecosystem. ANPP variations were undetectable during wet, normal and dry years (P = 0Á25). Our finding supported the hypothesis that temporal site-specific ANPP variations were less regulated by a single factor. The temporal PUE declined linearly with increasing annual precipitation, and the slope was obviously steeper than that of spatial patterns. More ANPP variability in an alpine meadow under warming conditions might occur via community transition in the north-eastern Qinghai-Tibetan Plateau.

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A new inner tracker based on a cylindrical gas electron-multiplier detector is under development to replace the current inner drift chamber of the BES III spectrometer. The BES III experiment is carried out at the BEPC II e[Formula: see text]e[Formula: see text] collider in Beijing at center-of-mass energies in the tau-charm region with a design luminosity of 1.0 [Formula: see text] 10[Formula: see text] cm[Formula: see text]s[Formula: see text]. The new inner tracker consists of three cylindrical layers of triple GEM surrounding the interaction point, covering 93% of solid angle. To fulfill physics requirements, a spatial resolution of 130 μm must be achieved. Both planar and cylindrical prototypes have been built and tested. A custom ASIC using UMC 110-nm technology has been designed to provide charge and time measurements—the first prototype is in testing. Notable and innovative aspects of the new inner tracker and the performance of the detector prototypes and readout ASIC are reported here.

A: For the upgrade of the inner tracker of the BESIII spectrometer, planned for 2018, a lightweight tracker based on an innovative Cylindrical Gas Electron Multiplier (CGEM) detector is now under development. The analogue readout of the CGEM enables the use of a charge centroid algorithm to improve the spatial resolution to better than 130 µm while loosening the pitch strip to 650 µm, which allows to reduce the total number of channels to about 10 000. The channels are readout by 160 dedicated integrated 64-channel front-end ASICs, providing a time and charge measurement and featuring a fully-digital output.The energy measurement is extracted either from the time-over-threshold (ToT) or the 10-bit digitisation of the peak amplitude of the signal. The time of the event is generated by quad-buffered low-power TDCs, allowing for rates in excess of 60 kHz per channel. The TDCs are based on analogue interpolation techniques and produce a time stamp (or two, if working in ToT mode) of the event with a time resolution better than 50 ps. The front-end noise, based on a CSA and a two-stage complex conjugated pole shapers, dominate the channel intrinsic time jitter, which is less than 5 ns r.m.s. The time information of the hit can be used to reconstruct the track path, operating the detector as a small TPC and hence improving the position resolution when the distribution of the cloud, due to large incident angle or magnetic field, is very broad.Event data is collected by an off-detector motherboard, where each GEM-ROC readout card handles 4 ASIC carrier FEBs (512 channels). Configuration upload and data readout between the off-detector electronics and the VME-based data collector cards are managed by bi-directional fibre optical links.This paper covers the design of a custom front-end electronics for the readout of the new inner tracker of the BESIII experiment, addressing the relevant design aspects of the detector electronics and the front-end ASIC for the CGEM readout, and reviewing the first silicon results of the chip prototype. K: Analogue electronic circuits; CMOS readout of gaseous detectors; Front-end electronics for detector readout; Micropattern gaseous detectors (MSGC, GEM, THGEM, RETHGEM, MHSP, MICROPIC, MICROMEGAS, InGrid, etc)