Entropy and biological systems: experimentally-investigated entropy-driven stacking of plant photosynthetic membranes

According to the Second Law of thermodynamics, an overall increase of entropy contributes to the driving force for any physicochemical process, but entropy has seldom been investigated in biological systems. Here, for the first time, we apply Isothermal Titration Calorimetry (ITC) to investigate the Mg21-induced spontaneous stacking of photosynthetic membranes isolated from spinach leaves. After subtracting a large endothermic interaction of MgCl2 with membranes, unrelated to stacking, we demonstrate that the enthalpy change (heat change at constant pressure) is zero or marginally positive or negative. This first direct experimental evidence strongly suggests that an entropy increase significantly drives membrane stacking in this ordered biological structure. Possible mechanisms for the entropy increase include: (i) the attraction between discrete oppositely-charged areas, releasing counterions; (ii) the release of loosely-bound water molecules from the inter-membrane gap; (iii) the increased orientational freedom of previously-aligned water dipoles; and (iv) the lateral rearrangement of membrane components.This work was supported consecutively by Australian Research Council grants (DP0664719 and DP 1093927)

Two-dimensional block Kalman filtering for image restoration

Includes bibliographical references.This paper is concerned with developing an efficient two-dimensional (2-D) block Kalman filtering for digital image restoration. A new 2-D multiinput, multioutput (MIMO) state-space structure for modeling the image generation process is introduced. This structure is derived by arranging a vector autoregressive (AR) model with a causal quarter-plane region of support in block form. This model takes into account the correlations of the image data in successive neighboring blocks and, as a result, reduces the edge effects prominent in the available Kalman strip filtering techniques. The degradation model for an infinite extent Linear space invariant (LSI) blur and white Gaussian (WG) noise is also modeled by an MIMO block state-space equation stemmed from a single-input single-output (SISO) 2-D state-space structure. The image generation model and the degradation model are combined to yield a composite block-state dynamic structure. The block Kalman filtering equations are obtained for this dynamic structure and then used to compute the suboptimal filter estimates of a noisy and blurred image

Quality of ultrasound biometry obtained by local health workers in a refugee camp on the Thai-Burmese border.

Objective: In a refugee camp on the Thai–Burmese border, accurate dating of pregnancy relies on ultrasound measurements obtained by locally trained health workers. The aim of this study was to substantiate the accuracy of fetal biometry measurements performed by locally trained health workers by comparing derived reference equations with those published for Asian and European hospitals. Methods: This prospective observational study included 1090 women who had a dating crown–rump length (CRL) scan and one study-appointed ultrasound biometry scan between 16 and 40 weeks of gestation. The average of two measurements of each of biparietal diameter, head circumference, abdominal circumference and femur length was used in a polynomial regression model for the mean and SD against gestational age (GA). The biometry equations obtained were compared with published equations of professional sonographers from Asian and European hospitals by evaluation of the SD and Z-scores of differences between models. Results: Reference equations of biometric parameters were found to fit cubic polynomial models. The observed SD values, for any given GA, of fetal biometric measurements obtained by locally trained health workers were lower than those previously reported by centers with professional sonographers. For nearly the entire GA range considered, the mean values of the Asian and European equations for all four biometric measurements were within the 90% expected range (mean ± 1.645 SD) of our equations. Conclusion: Locally trained health workers in a refugee camp on the Thai–Burmese border can obtain measurements that are associated with low SD values and within the normal limits of published Asian and European equations. The fact that the SD values were lower than in other studies may be explained by the use of the average of two measurements, CRL dating or motivation of the locally trained sonographer

GaInNAs-based Hellish-vertical cavity semiconductor optical amplifier for 1.3 μm operation

Hot electron light emission and lasing in semiconductor heterostructure (Hellish) devices are surface emitters the operation of which is based on the longitudinal injection of electrons and holes in the active region. These devices can be designed to be used as vertical cavity surface emitting laser or, as in this study, as a vertical cavity semiconductor optical amplifier (VCSOA). This study investigates the prospects for a Hellish VCSOA based on GaInNAs/GaAs material for operation in the 1.3-μm wavelength range. Hellish VCSOAs have increased functionality, and use undoped distributed Bragg reflectors; and this coupled with direct injection into the active region is expected to yield improvements in the gain and bandwidth. The design of the Hellish VCSOA is based on the transfer matrix method and the optical field distribution within the structure, where the determination of the position of quantum wells is crucial. A full assessment of Hellish VCSOAs has been performed in a device with eleven layers of Ga0.35In0.65N0.02As0.08/GaAs quantum wells (QWs) in the active region. It was characterised through I-V, L-V and by spectral photoluminescence, electroluminescence and electro-photoluminescence as a function of temperature and applied bias. Cavity resonance and gain peak curves have been calculated at different temperatures. Good agreement between experimental and theoretical results has been obtained

Keanekaragaman Jenis Tumbuhan Paku-pakuan (Pteridophyta) di Desa Bemban Kawasan Hutan Lindung Gunung Ambawang Kecamatan Kubu Kabupaten Kubu Raya

Research on Fern Diversity (Pteridophyta) In Bemban village In Mount Ambawang Protected Forest Kubu Kubu Raya District of West Kalimantan Province was held on September 16 th to October 7 th , 2013. Sampling plot was taken purposive where there were many fern found. There were four sampling plot based on height. Plot I located in 50-150 m above sea level altitude, plot II in 150-250 m above sea level altitude, plot III in 250-350 m above sea level altitude,and plot IV in 50-150 m above sea level altitude (rubber plantations). Each sampling plot 40 m x 40 m, divided into 160 subplot 2 m x 5 m aech. There were 13 fern species with 4162 individual these species consist of 8 terresterial fern with 3799 individual, and 5 epiphytic fern with 813 individuals. The plot at altitude of 50-150 m,were dominated by Lygodium circinatum and Asplenium nidus, altitude 150-250 m were dominated by Acrostichum spesiocum and Asplenium nidus, altitude 250-350 m dominated by Selaginella wildenowii, Asplenium longisimmum height of 50-150 m asl (rubber plantation) dominated by Nephrolepis biserrata and Asplenium nidus. The highest diversity index value was at altitude 150-250 m (2,043) which means the species diversity of ferns were low. Similarity index was highest between altitude 250-350 m and altitde 50-150 m in rubber plantation,in the value 5,638 %. It means between thw different plot there is no similarity (¤ 25 %). Keywords: Ferns, biodiversity, forest protected mount Ambaw