MSSS Research Articles

A 12-bit single slope ADC with multi-step structure and ramp calibration technique for image sensors

This paper presents a novel multi-step single slope analog to digital converter (MS SS ADC). The proposed ADC splits the 12-bit conversion into 3 steps, including 1-bit half section decision, 4-bit coarse conversion, and finally 8-bit fine conversion with 1-bit redundancy. The conversion step is substantially reduced from conventional 4096 to 276. The linearity of the ADC is guaranteed by a stable common mode voltage of the comparator varying only within 31.25 mV. Moreover, two high-accuracy ramp calibration techniques are utilized to correct the current variation in the fine ramp and the slope error between the coarse and fine ramps. A hybrid comparator is utilized in the ADC to save power while maintaining the performance. The ADC is designed and simulated in 0.18 μm CMOS process with 7.5 μm width. The differential nonlinearity and integral nonlinearity of the proposed ADC are reduced from +0.3/-1 LSB and +3.1/-2.55 LSB to +0.3/-0.3 LSB and +1/-0.45 LSB at 61.7 kS/s sample rate by the calibrations.

Skewness and kurtosis of multivariate Markov-switching processes

Exact formulae are provided for the calculation of multivariate skewness and kurtosis of Markov-switching Vector Auto-Regressive (MS VAR) processes as well as for the general class of MS state space (MS SS) models. The use of the higher-order moments in non-linear modeling is illustrated with two examples. A Matlab code that implements the results is available from the authors.

土地利用变化对东北温带幼龄林土壤碳氮磷含量及其化学计量特征的影响

Anthropogenic land use change alters the equilibrium among soil carbon( C),nitrogen( N),and phosphorus( P) in the forest ecosystem,likely affecting the biogeochemical cycles. In this study,conducted in northeastern China,we measured C,N,and P contents along soil profiles in adjacent sapling stands identical in age( 10 years) and primary vegetation,but differing in land use type. Land use types included naturally regenerated stands without soil disturbance( NS),moderately disturbed stands( two-year interplanting of soybean after artificial reforestation,MS),and severely disturbed stands( natural reforestation after planting Panax ginseng for 10 years,SS). Our objective was to examine the effects of land use change on soil C,N,and P contents and their stoichiometry. Our results showed that:( 1) Land use change significantly altered both top- and sub-soil C contents,which descended in the order NS MS SS for each soil horizon. However,land use markedly influenced only top-soil N contents and did not significantly influence P content alongthe entire soil profile( P 0. 05). These results suggest differing sensitivities of elements to land use change.( 2) The C /N and C / P ratios among the three land use types were lowest for SS and differed between NS and MS depending on the soil horizon. Vertical patterns of C / N and C / P ratios differed among land use types,but N / P ratio was consistently constrained by land use change. N / P ratios descended in the order NS MS SS within each soil horizon and decreased with soil depth( P 0. 05),suggesting that N/P may be a better ecological indicator of response to land use change than C/N and C/P.( 3) Land use change significantly affected coupled relationships between C-N,C-P,and N-P. Soil C and N contents were linearly correlated( P 0. 001),regardless of the land use type,with a common slope of 11. 1 but significantly different intercepts( P 0. 001). This result,together with the synthesis of published local and global datasets,reflects a largescale general C-N relationship and a small-scale heterogeneous response of C-N stoichiometry to local land use change.

The protease inhibitor PI*S allele and COPD: a meta-analysis

In many countries, the protease inhibitor (SERPINA1) PI*S allele is more common than PI*Z, the allele responsible for most cases of chronic obstructive pulmonary disease (COPD) due to severe alpha 1-antitrypsin deficiency. However, the risk of COPD due to the PI*S allele is not clear. The current authors located studies that addressed the risk of COPD or measured lung function in individuals with the PI SZ, PI MS and PI SS genotypes. A separate meta-analysis for each genotype was performed. Aggregating data from six studies, the odds ratio (OR) for COPD in PI SZ compound heterozygotes compared with PI MM (normal) individuals was significantly increased at 3.26 (95% confidence intervals (CI): 1.24-8.57). In 17 cross-sectional and case-control studies, the OR for COPD in PI MS heterozygotes was 1.19 (95%CI: 1.02-1.38). However, PI MS genotype was not associated with COPD risk after correcting for smoking. Furthermore, mean forced expiratory volume in one second, a measure of airflow obstruction and a defining feature of COPD, did not differ between PI MS and PI MM individuals. There were not enough cases to summarise the risk of COPD in PI SS homozygotes. In conclusion, the results show that the PI SZ genotype is a significant risk factor for chronic obstructive pulmonary disease. The risk of chronic obstructive pulmonary disease due to the PI MS genotype is not substantially elevated.

Persistence at a Difficult Task with Alternative Task of Intermediate Difficulty: Some Comments on Feather's Study

Abstract Nygard, R. 1976. Persistence at a Difficult Task with Alternative Task of Intermediate Difficulty: Some Comments on Feather's Study. Scand. J. educ. Res. 20, 41‐48. According to Atkinson the motivation to avoid failure among subjects (Ss) in whom the motive to avoid failure is stronger than the motive to achieve success (Mf > Ms) reaches its maximum when the subjective probability of success (P3) is .50. On this basis Feather suggests that when Mf> Ms Ss are confronted with a very difficult task (Ps Ms Ss. An alternative, probabilistic use of the achievement motivation theory is suggested, according to which the likelihood of a shift to the alternative task should be higher among Mf > Ms Ss with a relatively high Ps ...