Analysis of continuous laser-irradiation resistance of liquid-crystal optical switch based on sapphire-substrate GaN.

Developing high-power laser technology and its applications necessitates improvements in the laser-irradiation resistance of liquid-crystal modulation devices. In this study, the thermal characteristics of substrate and electrode materials, including sapphire-substrate indium tin oxide (ITO) electrodes, K9 glass-substrate ITO electrodes, sapphire-substrate gallium nitride (GaN) electrodes, and liquid-crystal optical switches, are investigated using simulation and experimental methods. Results show that the sapphire-substrate GaN electrode demonstrates the best heat dissipation and that the maximum temperature at the center of the spot under 75 W laser irradiation is 319 K, 52 K lower than that of an equally thick sapphire-substrate ITO electrode and 225 K lower than that of an equally thick K9 glass-substrate ITO electrode (steady state and test time >2min). Additionally, the experimental results show that the liquid-crystal optical switch, comprising a sapphire substrate and GaN electrode, can endure continuous laser irradiation up to 18 W with a switching ratio of approximately 20:1. The optical switch with GaN electrodes on a sapphire substrate can endure a power density of 156W/c m 2, much higher than that (21W/c m 2, steady state and test time >2min) tolerable by the liquid-crystal optical switch with ITO transparent electrodes and K9 glass substrates.

A novel lightweight deep learning approach for simultaneous optic cup and optic disc segmentation in glaucoma detection.

Glaucoma is a chronic neurodegenerative disease that can result in irreversible vision loss if not treated in its early stages. The cup-to-disc ratio is a key criterion for glaucoma screening and diagnosis, and it is determined by dividing the area of the optic cup (OC) by that of the optic disc (OD) in fundus images. Consequently, the automatic and accurate segmentation of the OC and OD is a pivotal step in glaucoma detection. In recent years, numerous methods have resulted in great success on this task. However, most existing methods either have unsatisfactory segmentation accuracy or high time costs. In this paper, we propose a lightweight deep-learning architecture for the simultaneous segmentation of the OC and OD, where we have adopted fuzzy learning and a multi-layer perceptron to simplify the learning complexity and improve segmentation accuracy. Experimental results demonstrate the superiority of our proposed method as compared to most state-of-the-art approaches in terms of both training time and segmentation accuracy.

[Photosynthetic characteristics of Leymus chinensis and Medicago sativa in artificial grassland]. / ç¾Šè‰å’Œç´«èŠ±è‹œè“¿äººå·¥è‰åœ°å ‰åˆç‰¹æ€§.

To explore the effect of monoculture and mixture sowing artificial grassland on the photosynthetic characteristics of Leymus chinensis and Medicago sativa, we determined the diurnal variation of photosynthetic properties of L. chinensis and M. sativa under different treatments. The results showed that the diurnal changes of net photosynthetic rate, blade temperature and transpiration rate of L. chinensis and M. sativa showed 'unimodal type' in monoculture, the stomatal conductance of M. sativa showed 'unimodal type', and the stomatal conductance and water use efficiency of L. chinensis showed 'bimodal type'. Under the mixed sowing treatment, the diurnal changes of net photosynthetic rate, blade temperature and transpiration rate of L. chinensis and M. sativa showed 'unimodal type', the stomatal conductance and water use efficiency of L. chinensis showed 'unimodal type', and the stomatal conductance of M. sativa showed 'bimodal type'. The peak photosynthetic rate of L. chinensis under mixture was signi-ficantly higher than that under monoculture, being 17.72 and 13.65 µmol CO2·m-2·s-1, respectively. Under monoculture and mixture sowing treatments, the chlorophyll content of L. chinensis was higher than that of M. sativa, nitrogen content of the leaves of L. chinensis was lower than that of M. sativa, and the nitrogen content in the leaves of mixture sowing L. chinensis was significantly higher than that of monoculture sowing L. chinensis, which were 27.60 and 22.55 g·kg-1, respectively. Net photosynthetic rates of L. chinensis and M. sativa were significantly positively correlated with stomatal conductance and transpiration rate, and significantly negatively correlated with intercellular CO2 concentration under different planting methods. Net photosynthetic rate of M. sativa was significantly positively correlated with blade temperature and water use efficiency. In summary, mixed sowing was beneficial to enhance nitrogen content of L. chinensis. Our results provided a theoretical basis for the response of the photosynthetic characteristics of forage to planting mode of artificial grassland.

Forms of nitrogen inputs regulate the intensity of soil acidification.

Soil acidification induced by reactive nitrogen (N) inputs can alter the structure and function of terrestrial ecosystems. Because different N-transformation processes contribute to the production and consumption of H+ , the magnitude of acidification likely depends on the relative amounts of organic N (ON) and inorganic N (IN) inputs. However, few studies have explicitly measured the effects of N composition on soil acidification. In this study, we first conducted a meta-analysis to test the effects of ON or IN inputs on soil acidification across 53 studies in grasslands. We then compared soil acidification across five different ON:IN ratios and two input rates based on long-term field N addition experiments. The meta-analysis showed that ON had weaker effects on soil acidification than IN when the N addition rate was above 20 g N m-2 year-1 . The field experiment confirmed the findings from meta-analysis: N addition with proportions of ON ≥ 20% caused less soil acidification, especially at a high input rate (30 g N m-2 year-1 ). Structural equation model analysis showed that this result was largely due to a relatively low rate of H+ production from ON as NH3 volatilization and uptake of ON and NH4 + by the dominant grass species Leymus chinensis (which are both lower net contributors to H+ production) result in less NH4 + available for nitrification (which is a higher net contributor to H+ production). These results indicate that the evaluation of soil acidification induced by N inputs should consider N forms and manipulations of relative composition of N inputs may provide an effective approach to alleviate the N-induced soil acidification.

Learning curve in ultrasound-guided vacuum-assisted excision of breast lesions for surgeons and ultrasound physicians.

Background: The varying experience of surgeons and ultrasound physicians, and their collaboration with physicians, may affect operation time and efficiency. We evaluated the learning curve of ultrasound-guided vacuum-assisted excision (VAE) of breast lesion with collaboration between different physicians, and assessed characteristics associated with operation time. Methods: The sample population of this retrospective study was divided into two groups: 49 consecutive patient surgeries completed by skilled surgeons and novice ultrasound physicians (U group); and 30 consecutive patient surgeries completed by skilled ultrasound physicians and novice surgeons (S group). Cumulative summation graphs were used to evaluate operation time and calculate the turning point of the learning curve. Patients in the U and S groups were divided into exploration stage and proficiency stage according to the turning point, and the differences in influencing factors were compared. A total of 548 patients who underwent vacuum-assisted breast excision performed by a combination of skilled surgeons and skilled ultrasound physicians were selected as the reference group (R group). The differences among the three groups were compared. The relationship between the operation time and other factors in the different groups was analyzed using linear regression. Results: The best learning curve of the sample population was the quadratic fitting equation, and the turning point was the 19th case in the U group and the 14th case in the S group. The total operation times in the proficiency stage were significantly shorter than those in the exploration stage in the U and S groups (P=0.012 and P=0.003, separately). Patient age, long diameter, short diameter, and depth of masses related to the operation time. Conclusions: Our data suggest the existence of different learning curves in ultrasound-guided vacuum-assisted excision for the collaborations of different stages surgeons and ultrasound physicians. Through the accumulation of experience, it is feasible to safely perform ultrasound-guided VAE of breast lesions.

A novel optical biosensor for in situ and small-scale monitoring of bacterial transport in saturated columns.

In situ monitoring techniques can provide new insight into bacterial transport after inoculating exogenous bacteria into contaminated soils for bioremediation. A real-time and non-destructive optical sensor (the optrode) was employed to monitor in situ transport of two fluorescently labelled bacteria - Green Fluorescent Protein (Gfp)-labelled, hydrophilic Pseudomonas putida and Tomato Fluorescent Protein (td)-labelled, hydrophobic Rhodococcus erythropolis, in a saturated sand column with and without rhamnolipid surfactant. In situ measurements were made at three sampling ports in the column with the optrode in two sets of column experiments. In Experiment 1, liquid samples were extracted for ex situ analyses (plate counts and fluorescence), while in Experiment 2 no liquid samples were extracted. Extracting liquid samples for ex situ analyses in Experiment 1 disturbed in situ measurements; in situ measured bacterial concentrations were lower, or a significant lag in breakthrough occurred relative to ex situ measurements. In Experiment 2, the optrode worked well in monitoring bacterial transport, which gave consistent transport parameters at each sampling port. Moreover, the optrode enabled the impact of bacterial hydrophobicity and rhamnolipid surfactant on bacterial transport to be observed. Specifically, hydrophilic P. putida was transported faster through the column than hydrophobic R. erythropolis; we infer from this result that fewer P. putida cells adsorb to sand particles than do R. erythropolis cells. The rhamnolipid surfactant enhanced the transport of both hydrophilic and hydrophobic bacteria. These two observations are consistent with Lifshitz-van der Waals forces and acid-base interactions between bacteria and sand.

Trade-off relationship and internal mechanism of plant leaf size and number in Hulunbuir grassland, China.

The trade-off between leaf size and number is the basis for plant growth strategies. It is of great significance to study the underlying mechanism of leaf size and number trade-offs for well understanding plant growth strategies. In this study, leaf size was expressed by the dry mass of single leaf, while leafing intensity was expressed by the number of leaves per unit stem volume. We used standardized major axis regression analysis method to examine the trade-off relationship between leaf size and number in Hulunbuir grassland. There was a significant negative isometric-growth trade-off between leaf size and number in Chenqicuogang (typical steppe) and Chenqibayi (meadow steppe). There was a significant negative allometric-growth trade-off between leaf size and number in Xeltala (meadow steppe). The underlying mechanism of the relationship between leaf size and number depended on the leaf and stem biomass allocation mechanism and the changes of the stem tissue density.

The removal of cyhalofop-butyl in soil by surplus Rhodopseudanonas palustris in wastewater purification.

The biorestoration of cyhalofop-butyl and fertility in soil using Rhodopseudanonas palustris (R. palustris) in the treated wastewater were investigated in this research. Cyhalofop-butyl was not degraded under control group. The treated wastewater containing R. palustris degraded cyhalofop-butyl and remediated fertility. Interestingly, the cyhalofop-butyl-hydrolyzing carboxylesterase gene was expressed after inoculation 24 h. Subsequently, the cyhalofop-butyl-hydrolyzing carboxylesterase were synthesized to degrade cyhalofop-butyl. The cyhalofop-butyl started to be degraded after inoculation 24 h. The cyhalofop-butyl as stimulus signal induced cyhalofop-butyl-hydrolyzing carboxylesterase gene expression through signal transduction pathway. This process took 24 h for R. palustris as they were ancient bacteria. The residual organics in the wastewater provided sufficient carbon sources and energy for R. palustris under three dosage groups. The new method completed the remediation of cyhalofop-butyl pollution, the improvement of soil fertility and soybean processing wastewater treatment simultaneously, and realized the resource reutilization of wastewater and R. palustris as sludge.

Mobility of pharmaceutical and personal care products in lime amended wastewater biosolids.

Lime amendment of biosolids can produce large quantities of hydroxyl ions and increase biosolids pH. The mobility of some pharmaceutical and personal care products (PPCPs) is closely correlated with the pH of biosolids. In this study the mobility of six PPCPs: erythromycin, fluoxetine, carbamazepine, naproxen, gemfibrozil and triclosan, was measured in unamended and lime-amended biosolids over 63days. Biosolids were equilibrated either a at pH range of 5.5-11.5 or cured over a time period up to 63days. The mobility was calculated as the proportion of PPCPs associated with the soluble phase after a given equilibrium time or a curing period. In unamended biosolids the mobility of erythromycin, fluoxetine, gemfibrozil and triclosan decreased, the mobility of naproxen increased and the mobility of carbamazepine was almost unchanged over 63days of curing. Compared to unamended biosolids, lime addition increased the mobility of erythromycin and naproxen by 21.7% and 33.8% respectively, but suppressed the mobility of carbamazepine, fluoxetine, gemfibrozil and triclosan by up to 100% after 63days. The pH influence on hydrophobicity and speciation of PPCPs correlated well with the mobility of erythromycin and fluoxetine, but only partially correlated with the mobility of the other 4 compounds over the pH of 5.5-11.5. Attenuated total reflectance Fourier transformed infrared (ATR-FTIR) and emission-excitation matrices (EEMs) provided spectroscopic evidences showing that the increases in amide and carboxylic groups, the decrease in polysaccharides, and the increases in humic substances in dissolved organic matter (DOM) may be responsible for the changes in the PPCPs' mobility. The effects of lime amendment lasted for approximately a month. The results of this work suggest that lime amendment prevents some PPCPs from being dissolved in biosolids soluble phases, but may not "lock" all PPCPs into biosolids.

Genistein attenuates brain damage induced by transient cerebral ischemia through up-regulation of Nrf2 expression in ovariectomized rats.

OBJECTIVE: Postmenopausal women possess higher incidence of stroke and worse prognosis. Although estrogen replacement therapy has obvious neuroprotective effects against stroke, it is always accompanied with several adverse effects and undesired outcomes. Genistein, a natural phytoestrogen, has been indicated to be a potential neuroprotective alternative for postmenopausal women against stroke. However, the role and mechanism of genistein's neuroprotective effects against stroke in ovariectomized rats have rarely been explored. METHODS: In this study, ovariectomized rats were treated with genistein (10 mg/kg) or vehicle daily for two weeks before they received middle cerebral artery occlusion (MCAO) and reperfusion. After 72 hours of reperfusion, the neurological function was evaluated by Garcia test, infarct volume was detected by 2,3,5-triphenyltetrazolium chloride staining, and neuronal damage was detected by Nissl staining. In addition, ROS production and the expression of Nrf2, NQO1 and cleaved-Caspase3 in the ischemic penumbra were detected. RESULTS: The results showed that genistein treatment significantly improved the neurological outcome, reduced infarct volume, increased Nrf2 and NQO1 expression, and reduced ROS production and cleaved-Caspase3 expression in ovariectomized rats. DISCUSSION: Our findings indicated that treatment with genistein could alleviated oxidative stress injury induced by cerebral ischemia in ovariectomized rats via promoting Nrf2 and NQO1 expression, which provide a new molecular mechanism for the neuroprotective effects of genistein against stroke in postmenopausal women.

Progressive multi-atlas label fusion by dictionary evolution.

Accurate segmentation of anatomical structures in medical images is important in recent imaging based studies. In the past years, multi-atlas patch-based label fusion methods have achieved a great success in medical image segmentation. In these methods, the appearance of each input image patch is first represented by an atlas patch dictionary (in the image domain), and then the latent label of the input image patch is predicted by applying the estimated representation coefficients to the corresponding anatomical labels of the atlas patches in the atlas label dictionary (in the label domain). However, due to the generally large gap between the patch appearance in the image domain and the patch structure in the label domain, the estimated (patch) representation coefficients from the image domain may not be optimal for the final label fusion, thus reducing the labeling accuracy. To address this issue, we propose a novel label fusion framework to seek for the suitable label fusion weights by progressively constructing a dynamic dictionary in a layer-by-layer manner, where the intermediate dictionaries act as a sequence of guidance to steer the transition of (patch) representation coefficients from the image domain to the label domain. Our proposed multi-layer label fusion framework is flexible enough to be applied to the existing labeling methods for improving their label fusion performance, i.e., by extending their single-layer static dictionary to the multi-layer dynamic dictionary. The experimental results show that our proposed progressive label fusion method achieves more accurate hippocampal segmentation results for the ADNI dataset, compared to the counterpart methods using only the single-layer static dictionary.

Progressive Label Fusion Framework for Multi-atlas Segmentation by Dictionary Evolution.

Accurate segmentation of anatomical structures in medical images is very important in neuroscience studies. Recently, multi-atlas patch-based label fusion methods have achieved many successes, which generally represent each target patch from an atlas patch dictionary in the image domain and then predict the latent label by directly applying the estimated representation coefficients in the label domain. However, due to the large gap between these two domains, the estimated representation coefficients in the image domain may not stay optimal for the label fusion. To overcome this dilemma, we propose a novel label fusion framework to make the weighting coefficients eventually to be optimal for the label fusion by progressively constructing a dynamic dictionary in a layer-by-layer manner, where a sequence of intermediate patch dictionaries gradually encode the transition from the patch representation coefficients in image domain to the optimal weights for label fusion. Our proposed framework is general to augment the label fusion performance of the current state-of-the-art methods. In our experiments, we apply our proposed method to hippocampus segmentation on ADNI dataset and achieve more accurate labeling results, compared to the counterpart methods with single-layer dictionary.

[A method for impedance measurements based on EEG acquisition system].

In the bioelectric measurement, the electrode impedance detection is an important index to the signal quality evaluation and sensor electrode contact condition. In this paper, a method of accurately measuring the electrode impedance based on EEG measurement system was put forward, the method is based on the constant current source excitation signals which are added to the human body, by monitoring the human voltage to measure the electrode impedance. And different reference resistor calibration calculation in different sections was used to reduce the effect of constant current source on the precision of measurement results to improve the measurement accuracy.

Germination shifts of C3 and C4 species under simulated global warming scenario.

Research efforts around the world have been increasingly devoted to investigating changes in C3 and C4 species' abundance or distribution with global warming, as they provide important insight into carbon fluxes and linked biogeochemical cycles. However, changes in the early life stage (e.g. germination) of C3 and C4 species in response to global warming, particularly with respect to asymmetric warming, have received less attention. We investigated germination percentage and rate of C3 and C4 species under asymmetric (+3/+6°C at day/night) and symmetric warming (+5/+5°C at day/night), simulated by alternating temperatures. A thermal time model was used to calculate germination base temperature and thermal time constant. Two additional alternating temperature regimes were used to test temperature metrics effect. The germination percentage and rate increased continuously for C4 species, but increased and then decreased with temperature for C3 species under both symmetric and asymmetric warming. Compared to asymmetric warming, symmetric warming significantly overestimated the speed of germination percentage change with temperature for C4 species. Among the temperature metrics (minimum, maximum, diurnal temperature range and average temperature), maximum temperature was most correlated with germination of C4 species. Our results indicate that global warming may favour germination of C4 species, at least for the C4 species studied in this work. The divergent effects of asymmetric and symmetric warming on plant germination also deserve more attention in future studies.

Arsenate-ferrihydrite systems from minutes to months: a macroscopic and ir spectroscopic study of an elusive equilibrium.

Sorption by ferrihydrite is an important control on As(V) concentrations in many oxic aquatic systems. There are significant discrepancies in reported sorption constants (log(KAs)), which presents a problem for quantifying and understanding this important system. A review of reported ferrihydrite-As(V) sorption studies indicated a positive correlation between reaction time used in the experiments and the log(KAs) values derived from the data. In this paper, we study the kinetics of As(V) sorption over ≈3000 h in nine systems with varying pH and As(V)/Fe. Ferrihydrite was stable in all systems containing As(V), and the [As(V)] in solution decreased linearly as a function of log(t) (termed Elovich kinetics) over the full 3000 h in most systems. A stable [As(V)] was only observed in systems with low As(V)/Fe and low pH. Apparent As(V) sorption constants were derived from the data at specific time intervals using the diffuse layer model and equations describing log(KAs) values as a function of time provide a way to describe this elusive equilibrium. IR spectra support the hypothesis that slow interparticle diffusion is responsible for the slow approach to equilibrium. This work resolves discrepancies in previous studies of As(V)-ferrihydrite and provides equations to allow for system appropriate log(KAs) values to be used.

Effects of salinity, temperature, and polyethylene glycol on the seed germination of sunflower (Helianthus annuus L.).

Salinization has severe influences on agriculture in the whole world. The main aims of this work were to evaluate osmotic effect and ion effect of NaCl on seed germination of three sunflower (Helianthus annuus L.) cultivars interacting with three alternating temperature regimes and to select the most salt tolerant cultivars to plant in the saline region. Seeds were germinated in the isotonic NaCl and polyethylene glycol (PEG) solutions of -0.45, -0.90, -1.34, -1.79, and -2.24 MPa at 10:20, 15:25, and 20:30 °C temperature regimes. Both NaCl and PEG inhibited germination, but the effects of NaCl were less as compared to that of PEG, which means that adverse effects of PEG on germination were due to osmotic effect rather than specific ion accumulation. For the three cultivars, higher germination occurred at 10:20 °C in NaCl treatments and at 20:30 °C in the isotonic PEG treatments. Among the three cultivars, Sandaomei (SDM) is the most tolerant to salt and PEG stress.

An extension Gaussian mixture model for brain MRI segmentation.

The segmentation of brain magnetic resonance (MR) images into gray matter (GM), white matter (WM) and cerebrospinal fluid (CSF) has been an intensive studied area in the medical image analysis community. The Gaussian mixture model (GMM) is one of the most commonly used model to represent the intensity of different tissue types. However, as a histogram-based model, the spatial relationship between pixels is discarded in the GMM, making it sensitive to noise. Herein we present a new framework which aims to incorporate spatial information into the standard GMM, where each pixel is assigned its individual prior by leveraging its neighborhood information. Expectation maximization (EM) is modified to estimate the parameters of the proposed method. The method is validated on both synthetic and real brain MR images, showing its effectiveness in the segmentation task.

[The effect of high-pass filter circuit on accurate measurement of ST-segment].

The high-pass filter which is designed to overcome the polarization voltage in the ECG measurements can affect the measurement of the ST-segment; but the accuracy of the ST-segment will have an impact on the diagnosis and treatment of heart diseases. This paper used the ECG detection platform to test the effect of the high-pass filter at different frequency and studied the effect of the high-pass filter on the ST segment to ensure proper use of different application modes.

[Research of micro sleeping monitor and evaluation system].

By studying of the pathology of human sleep and respiration disorder diseases, the method of sleep and respiration measurement, the evaluation index, a kind of micro sleep monitor and evaluation system was designed. Based on the methods of spectrum absorption and force changing, using high performance pulse oxygen saturation monitoring technology and respiration monitoring technology, developing a low-cost, high usability sleep monitor system which is convenience for family using. It can measure the signal of human oxygen saturation and chest respiration, can improve the quality of signal and reliable from arithmetic and sensor installing.