[Development and Clinical Application of Multifunctional Inflation-Free Lumpectomy Aid].

To investigate the value of self-developed air-free laparoscopic auxiliary instruments in the clinical application of thyroid diseases. The clinical data of 70 transaxillary and 45 transareolar air-free laparoscopic surgeries for thyroid cancer and 40 conventional open surgeries were retrospectively compared. The transaxillary and transareolar laparoscopic groups had significantly longer operative times than the open group, while the postoperative satisfaction was higher in the endoscopic group than in the open group. This set of instruments has advantage of novel design, scientific structure, safe application. It can be compatible with a variety of thyroid and breast air-free laparoscopic procedures, which can promote the development and popularization of laparoscopic technology.

Moderate mass loss enhances flight performance via alteration of flight kinematics and postures in a passerine bird.

Many birds experience fluctuations in body mass throughout the annual life cycle. The flight efficiency hypothesis posits that adaptive mass loss can enhance avian flight ability. However, whether birds can increase additional wing loading following mass loss and how birds adjust flight kinematics and postures remain largely unexplored. We investigated physiological changes in body condition in breeding female Eurasian tree sparrows (Passer montanus) through a dietary restriction experiment and determined the changes in flight kinematics and postures. Body mass decreased significantly, but the external maximum load and mass-corrected total load increased significantly after 3 days of dietary restriction. After 6 days of dietary restriction (DR6), hematocrit, pectoralis and hepatic fat content, take-off speed, theoretical maximum range speed and maximum power speed declined significantly. Notably, the load capacity and power margin remained unchanged relative to the control group. The wing stroke amplitude and relative downstroke duration were not affected by the interaction between diet restriction and extra load. Wing stroke amplitude significantly increased after DR6 treatment, while the relative downstroke duration significantly decreased. The stroke plane angle significantly increased after DR6 treatment only in the load-free condition. In addition, the sparrows adjusted their body angle and stroke plane angle in response to the extra load, but stroke amplitude and wingbeat frequency remained unchanged. Therefore, birds can maintain and even enhance their flight performance by adjusting flight kinematics and postures after a short-term mass loss.

Will "Air Eutrophication" Increase the Risk of Ecological Threat to Public Health?

Aquatic eutrophication, often with anthropogenic causes, facilitates blooms of cyanobacteria including cyanotoxin producing species, which profoundly impact aquatic ecosystems and human health. An emerging concern is that aquatic eutrophication may interact with other environmental changes and thereby lead to unexpected cascading effects on terrestrial systems. Here, we synthesize recent evidence showing the possibility that accelerating eutrophication will spill over from aquatic ecosystems to the atmosphere via "air eutrophication", a novel concept that refers to a process promoting the growth of airborne algae, some of them with the capacity to produce toxic compounds for humans and other organisms. Being catalyzed by various anthropogenic forcings─including aquatic eutrophication, climate warming, air contamination, and artificial light at night─accelerated air eutrophication may be expected in the future, posing a potentially increasing risk of threat to public health and the environment. So far knowledge of this topic is sparse, and we therefore consider air eutrophication a potentially important research field and propose an agenda of cross-discipline research. As a contribution, we have calculated a tolerable daily intake of 17 ng m-3 day-1 for the nasal intake of microcystins by humans.

The effect of precipitation timing on phylogenetic and functional community structure in a semi-arid steppe.

Changes in the amount and timing of precipitation may affect plant species coexistence. However, little is known about how these changes in precipitation structure plant communities. Here, we conducted a 6-year field precipitation manipulation experiment in the semi-arid steppe of Inner Mongolia, China, to assess the importance of species extinction and colonization in community assembly by incorporating information on phylogenetic and functional relatedness. Our results demonstrated that the decline in plant species richness under decreasing precipitation in the late and entire growing season could be attributed to a decrease in species colonization and an increase in species loss, respectively. The increase in species richness under increasing precipitation in the late growing season was mainly caused by increases in colonizing species. The loss of species that were more closely related to other residents under decreasing precipitation in the late growing season did not alter patterns of phylogenetic overdispersion, and the colonization of species that were more distantly related to residents under increasing precipitation in the late growing season shifted functional relatedness from clustering to randomness. Increasing precipitation may weaken the strength of environmental filtering induced by water stress in this semi-arid steppe and thus increase the probability of successful colonization of functionally dissimilar species relative to residents. Our study suggests that incorporating information on the functional and phylogenetic relatedness of locally lost resident species and the colonization of new species into analyses of community assembly processes can provide new insights into the general responses of plant communities to global change.

Effects of different levels of rapeseed cake containing high glucosinolates in steer ration on rumen fermentation, nutrient digestibility and the rumen microbial community.

This trial was conducted to study the effects of dietary rapeseed cake (RSC) containing high glucosinolates (GLS) on rumen fermentation, nutrient digestion and the rumen microbial community in steers. Eight growing steers and four rations containing RSC (GLS 226·1 µmol/g DM) at 0·00, 2·65, 5·35 and 8·00 % DM were assigned in a replicate 4 × 4 Latin square design. The results indicated that increasing RSC levels increased the ruminal concentration of thiocyanate (SCN) (P < 0·01), decreased the ruminal concentration of ammonia nitrogen (NH3-N) and the molar proportion of isovalerate (P < 0·05), did not affect the ruminal concentration of total volatile fatty acids (P > 0·05), decreased the crude protein (CP) digestibility (P < 0·05) and increased the ether extract (EE) digestibility (P < 0·01). Increasing RSC levels tended to decrease the abundances of ruminal Ruminobacter amylophilus (P = 0·055) and Ruminococcus albus (P = 0·086) but did not affect methanogens, protozoa, fungi and other bacteria (P > 0·05). Increasing RSC levels in the ration did not affect the ruminal bacterial diversity (P > 0·05), but it increased the operational taxonomic units and the bacterial richness (P < 0·05) and affected the relative abundances of some bacteria at the phylum level and genus level (P < 0·05). In conclusion, RSC decreased the ruminal concentration of NH3-N and the CP digestibility, increased the EE digestibility and partly affected the ruminal bacterial community. SCN, as the metabolite of GLS, could be a major factor affecting these indices.

Investigation of doping effects of different noble metals for ethanol gas sensors based on mesoporous In2O3.

Elaborating the sensitization effects of different noble metals on In2O3has great significance in providing an optimum method to improve ethanol sensing performance. In this study, long-range ordered mesoporous In2O3has been fabricated through replicating the structure of SBA-15. Different noble metals (Au, Ag, Pt and Pd) with the same doping amount (1 at%) have been introduced by anin situdoping routine. The results of the gas sensing investigation indicate that the gas responses towards ethanol can be obviously increased by doping different noble metals. In particular, the best sensing performance towards ethanol detection can be achieved through Pd doping, and the sensors based on Pd-doped In2O3not only possess the highest response (39.0-100 ppm ethanol) but also have the shortest response and recovery times at the optimal operating temperature of 250 °C. The sensing mechanism of noble metal doped materials can be attributed to the synergetic effect combining 'catalysis' and 'electronic and chemical sensitization' of noble metals. In particular, the chemical state of the noble metal also has a great influence on the gas sensing mechanism. A detailed explanation of the enhancement of gas sensing performance through noble metal doping is presented in the gas sensing mechanism part of the manuscript.

Coping with extremes: High-altitude sparrows enhance metabolic and thermogenic capacities in the pectoralis muscle and suppress in the liver relative to their lowland counterparts.

Animals living at high altitudes are challenged by the extreme environmental conditions of cold temperature and hypobaric hypoxia. It is not well understood how high-altitude birds enhance the capacity of metabolic thermogenesis and allocate metabolic capacity in different organs to maximize survival in extreme conditions of a cold winter. The Qinghai-Tibet Plateau (QTP) is the largest and highest plateau globally, offering a natural laboratory for investigating coping mechanisms of organisms inhabiting extreme environments. To understand the adaptive strategies in the morphology and physiology of small songbirds on the QTP, we compared plasma triiodothyronine (T3), pectoralis muscle mitochondrial cytochrome c oxidase (COX) and state IV capacities, the expression of peroxisome proliferator-activated receptor γ coactivator α (PGC-1α), adenine nucleotide translocase (ANT), uncoupling protein (UCP), and adenosine monophosphate-dependent kinase (AMPK) α1 mRNA in the pectoralis and liver of Eurasian tree sparrows (Passer montanus) from high-altitude (3,230 m), medium-altitude (1400 m), and low-altitude (80 m) regions. Our results showed that high-altitude sparrows had greater body masses, longer wings and tarsometatarsi, but comparable bill lengths relative to medium- and low-altitude individuals. High-altitude sparrows had higher plasma T3 levels and pectoralis muscle mitochondrial COX capacities than their lowland counterparts. They also upregulated the pectoralis muscle mRNA expression of UCP, PGC-1α, and ANT proteins relative to low-altitude sparrows. Unlike pectoralis, high-altitude sparrows significantly down-regulated hepatic AMPKα1 and ANT protein expression as compared with their lowland counterparts. Our results contribute to understanding the morphological, biochemical, and molecular adaptations in free-living birds to cope with the cold seasons in the extreme environment of the QTP.

The effect of air pollution on immunological, antioxidative and hematological parameters, and body condition of Eurasian tree sparrows.

Air pollution constitutes potential threats to wildlife and human health; therefore, it must be monitored accurately. However, little attention has been given to understanding the toxicological effects induced by air pollution and the suitability of bird species as bioindicators. The Eurasian tree sparrow (Passer montanus), a human commensal species, was used as a study model to examine toxic metal accumulation, retention of particulate matter (PM), immunological and antioxidant capacities, and hematological parameters in birds inhabiting those areas with relatively higher (Shijiazhuang city) or lower (Chengde city) levels of PM2.5 and PM10 in China. Our results showed that Shijiazhuang birds had significantly more particle retention in the lungs and toxic metal (including aluminum, arsenic, cadmium, iron, manganese, and lead) accumulation in the feathers relative to Chengde birds. They also had lower superoxide dismutase, albumin, immunoglobulin M concentrations in the lung lavage fluid, and total antioxidant capacity (T-AOC) in the lungs and hearts. Furthermore, although they had higher proportions of microcytes, hypochromia, and polychromatic erythrocytes in the peripheral blood (a symptom of anemia), both populations exhibited comparable body conditions, white cell counts, heterophil and lymphocyte ratios, and plasma T-AOC and corticosterone levels. Therefore, our results not only confirmed that Shijiazhuang birds experienced a greater burden from environmental PM and toxic metals but also identified a suite of adverse effects of environmental pollution on immunological, antioxidative, and hematological parameters in multiple tissues. These findings contribute to our understanding of the physiological health consequences induced by PM exposure in wild animals. They suggest that free-living birds inhabiting urban areas could be used as bioindicators for evaluating the adverse effects induced by environmental pollution.

Coping with extremes: Remarkably blunt adrenocortical responses to acute stress in two sympatric snow finches on the Qinghai-Tibet Plateau during winter relative to other seasons.

The extreme climatic conditions (ECCs) of the Qinghai-Tibet Plateau impose strong selective pressures on the evolution of phenotypic traits in free-living animals. It is not well understood how animals on the Qinghai-Tibet Plateau modify their adrenocortical functions in response to both predictable and unpredictable events of ECCs, especially when the available resources are lowest during the wintering life-history stage. To uncover potential physiological mechanisms, we studied the life history stage dependent features of morphology, the plasma corticosterone response to acute stress and brain glucocorticoid receptor (GR) and mineralocorticoid receptor (MR) mRNA expression in two sympatric snow finches: the white-rumped snow finch (Onychostruthus taczanowskii, WRSF); and the rufous-necked snow finch, Pyrgilauda ruficollis, RNSF) in Qinghai Province, China. Our results showed that (a) baseline corticosterone and stressor-induced corticosterone levels significantly varied with life history stage, but not between the species; (b) in WRSF, GR mRNA expression in the paraventricular nucleus was higher in the wintering stage compared to the pre-basic molt stage. There were no differences in hippocampus MR mRNA expression between stages in either species; (c) in the wintering stage, the suppression of corticosterone secretion in both species was an unexpected strategy in free-living animals. Both convergent and divergent phenotypic traits of adrenocortical responses to acute stress in two sympatric snow finches contribute to our understanding of the coping mechanisms of closely related species in the severe winter on the Qinghai-Tibet Plateau.

Histone Deacetylase Inhibitor SAHA Improves High Salinity Tolerance Associated with Hyperacetylation-Enhancing Expression of Ion Homeostasis-Related Genes in Cotton.

Histone acetylation plays an important role in regulation of chromatin structure and gene expression in terms of responding to abiotic stresses. Histone acetylation is modulated by histone deacetylases (HDACs) and histone acetyltransferases. Recently, the effectiveness of HDAC inhibitors (HDACis) for conferring plant salt tolerance has been reported. However, the role of HDACis in cotton has not been elucidated. In the present study, we assessed the effects of the HDACi suberoylanilide hydroxamic acid (SAHA) during high salinity stress in cotton. We demonstrated that 10 µM SAHA pretreatment could rescue of cotton from 250 mM NaCl stress, accompanied with reduced Na+ accumulation and a strong expression of the ion homeostasis-related genes. Western blotting and immunostaining results revealed that SAHA pretreatment could induce global hyperacetylation of histone H3 at lysine 9 (H3K9) and histone H4 at lysine 5 (H4K5) under 250 mM NaCl stress, indicating that SAHA could act as the HDACi in cotton. Chromatin immunoprecipitation and chromatin accessibility coupled with real time quantitative PCR analyses showed that the upregulation of the ion homeostasis-related genes was associated with the elevated acetylation levels of H3K9 and H4K5 and increased chromatin accessibility on the promoter regions of these genes. Our results could provide a theoretical basis for analyzing the mechanism of HDACi application on salt tolerance in plants.

Evaluation of radiotherapy combined with targeted therapy and concurrent radiotherapy, chemotherapy in the treatment of Non-Small Cell Lung Cancer with brain metastasis.

OBJECTIVE: To compare and analyze the clinical efficacy of brain radiotherapy combined with targeted therapy and concurrent radiotherapy and chemotherapy in the treatment of non-small cell lung cancer (NSCLC) with brain metastasis. METHODS: Fifty-eight patients with NSCLC with brain metastasis who were admitted to our hospital between October 2016 and October 2017 were randomly divided into a control group and an observation group, 29 cases in each group. The control group was treated with concurrent radiotherapy and chemotherapy, while the observation group was treated with whole brain radiotherapy plus targeted therapy. The disease control rate, adverse reactions and survival condition were compared between the two groups. RESULTS: The disease control rate of the observation group was 68.97%, significantly higher than 41.38% of the control group (P<0.05); the total incidence of adverse reactions in the observation group was 6.90%, significantly lower than 24.14% of the control group (P<0.05); the median survival time of the observation group was (16.81±5.32) months, significantly longer than that of the control group ((9.76±3.25) months). The one-year and two-year survival rates in the observation group were significantly higher than those in the control group (P<0.05). CONCLUSION: Whole brain radiotherapy combined with targeted therapy is superior to concurrent radiotherapy and chemotherapy in the treatment of NSCLC with brain metastasis and has high safety. It can effectively prolong the life span of patients and is worth clinical promotion and application.

Polyester Fabric's Fluorescent Dyeing in Supercritical Carbon Dioxide and its Fluorescence Imaging.

As one of the most important coumarin-like dyes, disperse fluorescent Yellow 82 exhibits exceptionally large two-photon effects. Here, it was firstly introduced into the supercritical CO2 dyeing polyester fabrics in this work. Results of the present work showed that the dyeing parameters such as the dyeing time, pressure and temperature had remarkable influences on the color strength of fabrics. The optimized dyeing condition in supercritical CO2 dyeing has been proposed that the dyeing time was 60 min; the pressure was 25 MPa and the temperature was 120 °C. As a result, acceptable products were obtained with the wash and rub fastness rating at 5 or 4-5. The polyester fabrics dyed with fluorescent dyes can be satisfied for the requirement of manufacturing warning clothing. Importantly, the confocal microscopy imaging technology was successfully introduced into textile fields to observe the distribution and fluorescence intensity of disperse fluorescent Yellow 82 on polyester fabrics. As far as we know, this is the first report about supercritical CO2 dyeing polyester fabrics based on disperse fluorescent dyes. It will be very helpful for the further design of new fluorescent functional dyes suitable for supercritical CO2 dyeing technique.

Dynamic interactions between corticosterone, corticosteroid binding globulin and testosterone in response to capture stress in male breeding Eurasian tree sparrows.

In birds, corticosterone (CORT), testosterone (T), and corticosteroid binding globulin (CBG) are involved in modulating the trade-off between reproduction and survival. In response to acute stress, increased total plasma CORT is a ubiquitous phenomenon while T levels can decrease, or remain unchanged. Since CORT and T bind competitively with CBG in birds, the underlying regulatory mechanisms and consequences of their dynamic interactions remain largely unknown. Here, we studied the dynamic changes of total CORT, T, and CBG, and estimated free and bound CORT and T in response to capture stress in male Eurasian tree sparrows (Passer montanus) across the nest building, egg-laying, and nestling stages. We predicted that free, bound and total hormone concentrations would increase for CORT and decrease for T in response to acute stress, and the relative magnitude of these changes would vary with life history stage. We found that baseline and stressed-induced CORT values did not vary across breeding sub-stages. However, total and bound CORT increased with stress while free remained unchanged. Baseline levels of total, free and bound T were highest during the nest building and it was the only stage in which all measures of T were affected by stress. Regardless of breeding stage or restraint stress, we did not detect a significant correlation between CORT and T. CBG was found to be mostly unoccupied by steroid hormones under stress and stress-free conditions and this likely provided an adequate buffer for changes in free levels of CORT and T during unpredictable environmental perturbations.

Life-history dependent relationships between body condition and immunity, between immunity indices in male Eurasian tree sparrows.

In free-living animals, recent evidence indicates that innate, and acquired, immunity varies with annual variation in the demand for, and availability of, food resources. However, little is known about how animals adjust the relationships between immunity and body condition, and between innate and acquired immunity to optimize survival over winter and reproductive success during the breeding stage. Here, we measured indices of body condition (size-corrected mass [SCM], and hematocrit [Hct]), constitutive innate immunity (plasma total complement hemolysis activity [CH50]) and acquired immunity (plasma immunoglobulin A [IgA]), plus heterophil/lymphocyte (H/L) ratios, in male Eurasian tree sparrows (Passer montanus) during the wintering and the breeding stages. We found that birds during the wintering stage had higher IgA levels than those from the breeding stage. Two indices of body condition were both negatively correlated with plasma CH50 activities, and positively with IgA levels in wintering birds, but this was not the case in the breeding birds. However, there was no correlation between CH50 activities and IgA levels in both stages. These results suggest that the relationships between body condition and immunity can vary across life-history stage, and there are no correlations between innate and acquired immunity independent of life-history stage, in male Eurasian tree sparrows. Therefore, body condition indices predict immunological state, especially during the non-breeding stage, which can be useful indicators of individual immunocompetences for understanding the variations in innate and acquired immunity in free-living animals.

[Value of nutritional risk screening in evaluating adverse clinical outcomes in children with severe pneumonia].

OBJECTIVE: To investigate the nutritional risk in children with severe pneumonia using the Screening Tool for the Assessment of Malnutrition in Paediatrics (STAMP) and the association between nutritional risk and adverse clinical outcomes. METHODS: According to the STAMP score, 216 children with severe pneumonia were classified into high nutritional risk group (HR group; n=98), moderate nutritional risk group (MR group; n=65), and low nutritional risk group (LR group; n=53). Fasting blood samples were collected to measure the levels of insulin-like growth factor-1 (IGF-1), adiponectin, leptin, non-esterified fatty acid (NEFA), albumin, transferrin, prealbumin, and retinol binding protein (RBP). The adverse clinical outcomes were recorded. RESULTS: Compared with the MR and LR groups, the HR group had significantly lower serum levels of IGF-1, leptin, adiponectin, prealbumin, and RBP, as well as a significantly higher serum level of NEFA (P<0.05). Compared with the MR and LR groups, the HR group had a significantly higher proportion of children admitted to the intensive care unit and a significantly longer duration of mechanical ventilation (P<0.05). The HR group had a significantly longer mean hospital stay and a significantly higher incidence rate of complications compared with the LR and MR groups (P<0.05). CONCLUSIONS: Nutritional risk screening has an important value in evaluating the clinical outcome of children with severe pneumonia, and children at a higher nutritional risk tend to have more adverse clinical outcomes.

Flying high: limits to flight performance by sparrows on the Qinghai-Tibet Plateau.

Limits to flight performance at high altitude potentially reflect variable constraints deriving from the simultaneous challenges of hypobaric, hypodense and cold air. Differences in flight-related morphology and maximum lifting capacity have been well characterized for different hummingbird species across elevational gradients, but relevant within-species variation has not yet been identified in any bird species. Here we evaluate load-lifting capacity for Eurasian tree sparrow (Passer montanus) populations at three different elevations in China, and correlate maximum lifted loads with relevant anatomical features including wing shape, wing size, and heart and lung masses. Sparrows were heavier and possessed more rounded and longer wings at higher elevations; relative heart and lung masses were also greater with altitude, although relative flight muscle mass remained constant. By contrast, maximum lifting capacity relative to body weight declined over the same elevational range, while the effective wing loading in flight (i.e. the ratio of body weight and maximum lifted weight to total wing area) remained constant, suggesting aerodynamic constraints on performance in parallel with enhanced heart and lung masses to offset hypoxic challenge. Mechanical limits to take-off performance may thus be exacerbated at higher elevations, which may in turn result in behavioral differences in escape responses among populations.

Occurrence, fate and interrelation of selected antibiotics in sewage treatment plants and their receiving surface water.

The occurrence and fate of 12 commonly used antibiotics, two fluoroquinolones (FQs), three sulfonamides (SAs), three macrolides (MLs), two ß-lactams and two tetracyclines (TCs), were studied in four sewage treatment plants (STPs) and their receiving water, the Huangpu River, Shanghai. The levels of selected antibiotics in the STPs ranged from ngL(-1) to µgL(-1), while ofloxacin (OFL) was predominant (reach up to 2936.94ngL(-1)). The highest and lowest proportions were of FQs (STP 1, STP 2 and STP 3) and TCs (in four STPs) respectively in both influents and effluents. And the second-highest proportion was of FQs in STP 4 (only 2% lower than the highest). What could be inferred was that the usage of TCs were extremely low while the usage of FQs were larger than other antibiotics in our study area. The elimination of antibiotics through these STPs was incomplete and a wide range of removal efficiencies (-442.8% to 100%) during the treatment was observed. Based on the mass loadings as well as the per-capita mass loadings of target antibiotics in four STPs, OFL was considered the primary contaminant herein. In the Huangpu River, 3 antibiotics were not detected in any water samples, while the detection frequencies of 4 antibiotics were 100%. The highest concentration detected in the river was 53.91ngL(-1) of sulfapyridine (SD). The Spearman correlation analysis of antibiotics in STPs and the nearby water samples suggests that the antibiotics discharged from some STPs might influence the receiving water to some extent. Moreover, most of the hazard quotient (HQ) values in STP effluents were one order magnitude higher than those in their receiving water. However, there is no imminent significant ecotoxicological risk caused by any single compound in the effluents and receiving waters.

No inhalation in combination with high frequency ventilation treatment in the treatment of neonatal severe respiratory failure.

OBJECTIVE: To discuss over NO inhalation (iNO) in combination with high frequency ventilation treatment in relieving clinical symptoms and respiratory state of patients with neonatal severe respiratory failure. METHODS: Ninety newborns with severe respiratory failure who received treatment in our hospital were selected for this study. They were divided into research group and control group according to visiting time. Patients in the control group were given conventional treatment in combination with high-frequency oscillatory ventilation, while patients in the research group were given iNO for treatment additionally besides the treatment the same as the control group. Changes of respiratory function indexes and arterial blood gas indexes of patients in the two groups were compared. Mechanical ventilation time, time of oxygen therapy and the length of hospital stay were recorded. Besides, postoperative outcome and the incidence of complications were analyzed. RESULTS: After treatment, the level of PaO2 of both groups significantly improved, and respiratory function indexes such as partial pressure of carbon dioxide in artery (PaCO2), oxygenation index (OI), fraction of inspiration O2 (FiO2) and mean arterial pressure (MAP) decreased (P<0.05); the improvement of various indexes of the research group was more obvious than that of the control group (P<0.05). Mechanical ventilation time, oxygen therapy time and the length of hospital stay of the research group was much shorter than those of the control group. The incidence of complications in the two groups had no statistically significant difference (P>0.05), but the clinical outcome of the research group was better than that of the control group. CONCLUSION: NO inhalation in combination with high frequency ventilation for treating neonatal severe respiratory failure is effective in improving blood gas index and respiratory function, enhance cure rate, and reduce the incidence of complications and mortality; hence it is safe and effective and worth clinical promotion.

Correlated spatio-temporal data collection in wireless sensor networks based on low rank matrix approximation and optimized node sampling.

The emerging low rank matrix approximation (LRMA) method provides an energy efficient scheme for data collection in wireless sensor networks (WSNs) by randomly sampling a subset of sensor nodes for data sensing. However, the existing LRMA based methods generally underutilize the spatial or temporal correlation of the sensing data, resulting in uneven energy consumption and thus shortening the network lifetime. In this paper, we propose a correlated spatio-temporal data collection method for WSNs based on LRMA. In the proposed method, both the temporal consistence and the spatial correlation of the sensing data are simultaneously integrated under a new LRMA model. Moreover, the network energy consumption issue is considered in the node sampling procedure. We use Gini index to measure both the spatial distribution of the selected nodes and the evenness of the network energy status, then formulate and resolve an optimization problem to achieve optimized node sampling. The proposed method is evaluated on both the simulated and real wireless networks and compared with state-of-the-art methods. The experimental results show the proposed method efficiently reduces the energy consumption of network and prolongs the network lifetime with high data recovery accuracy and good stability.