AIM:To explore the factors influencing individuals’willingness to participate in ophthalmic clinical trials.METHODS:A questionnaire survey was conducted from January to April 2021 among patients and their family memb...AIM:To explore the factors influencing individuals’willingness to participate in ophthalmic clinical trials.METHODS:A questionnaire survey was conducted from January to April 2021 among patients and their family members at Zhongshan Ophthalmic Center,Sun Yat-sen University,in Guangzhou,China.The survey gathered data on respondents’willingness,demographic and socioeconomic profiles,as well as their reasons and concerns regarding engagement in clinical trials.RESULTS:Of the 1078 residents surveyed(mean age 31.2±13.1y;65.8%females)in Guangzhou,749(69.5%)expressed a willingness to participate in future ophthalmic clinical trials.Specific characteristics associated with greater willingness included a younger age,lower annual income,higher education,prior participation experience,previous ophthalmic treatment,and a better understanding of clinical trials.With the exception of age,these characteristics were significantly linked to a higher willingness.The primary barrier to participation,expressed by 64.8%of those willing and 54.4%of those unwilling,was“Uncertain efficacy”.In terms of motivations,the willing group ranked“Better therapeutic benefits”(35.0%),“Professional monitoring”(34.3%),and“Trust in healthcare professionals”(33.1%)as their top three reasons,whereas the unwilling participants indicated“Full comprehension of the protocol”(46.2%)as the key facilitator.CONCLUSION:This study reveals a substantial willingness to participate in ophthalmic clinical trials and demonstrates the predictive role of demographic and socioeconomic factors.Variations in motivators and concerns between willing and unwilling participants highlight the significance of tailored recruitment strategies.Importantly,the need for and trust in healthcare professionals stand out as powerful motivations,underscoring the importance of enhancing physician-patient relationships,adopting patient-centered communication approaches,and addressing individualized needs to improve accrual rates.展开更多
BACKGROUND Alveolar recruitment maneuvers(ARMs)may lead to transient hypotension,but the clinical characteristics of this induced hypotension are poorly understood.We investigated the characteristics of ARM-related hy...BACKGROUND Alveolar recruitment maneuvers(ARMs)may lead to transient hypotension,but the clinical characteristics of this induced hypotension are poorly understood.We investigated the characteristics of ARM-related hypotension in patients who underwent laparoscopic colorectal cancer resection.AIM To investigate the characteristics of ARM-related hypotension in patients who underwent laparoscopic colorectal cancer resection.METHODS This was a secondary analysis of the PROtective Ventilation using Open Lung approach Or Not trial and included 140 subjects.An ARM was repeated every 30 min during intraoperative mechanical ventilation.The primary endpoint was ARM-related hypotension,defined as a mean arterial pressure(MAP)<60 mmHg during an ARM or within 5 min after an ARM.The risk factors for hypotension were identified.The peri-ARM changes in blood pressure were analyzed for the first three ARMs(ARM_(1,2,3))and the last ARM(ARMl_(ast)).RESULTS Thirty-four subjects(24.3%)developed ARM-related hypotension.Of all 1027 ARMs,37(3.61%)induced hypotension.More ARMs under nonpneumoperitoneum(33/349,9.46%)than under pneumoperitoneum conditions(4/678,0.59%)induced hypotension(P<0.01).The incidence of hypotension was higher at ARM_(1)points than at non-ARM_(1)points(18/135,13.3%vs 19/892,2.1%;P<0.01).The median percentage decrease in the MAP at ARM1 was 14%.Age≥74 years,blood loss≥150 mL and peak inspiratory pressure under pneumoperitoneum<24 cm H_(2)O were risk factors for ARM-related hypotension.CONCLUSION When the ARM was repeated intraoperatively,a quarter of subjects developed ARM-related hypotension,but only 3.61%of ARMs induced hypotension.ARM-related hypotension most occurred in a hemodynamically unstable state or a hypovolemic state,and in elderly subjects.Fortunately,ARMs that were performed under pneumoperitoneum conditions had less impact on blood pressure.展开更多
Enrolling in clinical trials could be time-sensitive and time-demanding tasks for the research site, especially if it is a private research organization compared to the research conducted at an academic or medical cen...Enrolling in clinical trials could be time-sensitive and time-demanding tasks for the research site, especially if it is a private research organization compared to the research conducted at an academic or medical center. Every study differs in various aspects, such as phases, study indication, eligibility criteria, etc. In terms of meeting the enrollment deadline, typically, the study indication and availability of the patient’s population at the geographical area of the research site would decide if the trial could be time-consuming. Patient recruitment and retention are critical for the success of every clinical trial;however, worldwide, this area is facing tremendous pressure and challenges. Globally 55% of clinical trials terminated due to low recruitment, with an average enrollment success rate of 40% for Phase III and IV trials. Over 80% of clinical trial attempts fail to enroll, extending the study and adding new study sites. In the United States, more than 80% of clinical trials fail to achieve targeted patient enrollment, and 30% of study participants discontinue participation. This article reviewed various factors hindering clinical trial recruitment and retention and suggested strategies to make the research site successful.展开更多
Concrete action on diversity and inclusion(D&I)is critical to companies’value creation and brand.Companies that intentionally fail to attract and retain a diverse talent pool will struggle to innovate,compete,and...Concrete action on diversity and inclusion(D&I)is critical to companies’value creation and brand.Companies that intentionally fail to attract and retain a diverse talent pool will struggle to innovate,compete,and prosper.The advantages of a diverse and inclusive workplace include the reduction of homogenous thinking and an increase in novel ideas and perspectives due to the wealth of talent from diverse backgrounds.Previous studies have focused on the benefits of corporate D&I from a corporate perspective;however,there is scant research on the impact of corporate D&I from employees’perspectives.Resultingly,this study,through an online questionnaire,proposes to examine the impact of employer brand D&I on potential employees in online recruitment channels from the perspective of potential employees.The study results indicate that most Chinese companies still exhibit low levels of D&I during recruitment.This study also included an empirical analysis of 267 valid samples,which showed that:(1)the D&I of employer brand perceptions positively impact job search intentions,behaviour,and decision making.(2)Companies’D&I has the most significant influence on job seekers’decision making,followed by behavioural influence and cognitive influence.(3)The type of job seeker plays a moderating role in the relationship between employer brand perception and job search intention,behaviour,and decision making.(4)Online recruitment’s increasing popularity amplifies employer branding’s effect.Based on the findings,this study suggests how companies can use D&I branding strategies to attract quality talent and increase job seekers’job search intentions.展开更多
This study developed a recruitment forecasting model based on a new concept of the stock recruitment relationship. No density-dependent effect in the relationship was assumed in the model, which showed that fluctuatio...This study developed a recruitment forecasting model based on a new concept of the stock recruitment relationship. No density-dependent effect in the relationship was assumed in the model, which showed that fluctuations in recruitment and spawning stock biomass of Japanese sardine in the northwestern Pacific can be explained mainly by environmental factors and the effects of fishing. The February Arctic Oscillation (AO) and sea surface temperature over the southern area of the Kuroshio Extension (30 - 35°N and 145 - 180°E;KEST) were used as the environmental factors. The recruitment forecasting model is proposed: The values for recruitment (), spawning stock biomass, (), in year t, forecast by this model accurately reproduced those estimated by tuning virtual population analysis (VPA), and the pattern of variability in the stock recruitment relationship was also reproduced well. In conclusion, a density-dependent effect does not necessarily have to be included to explain the large variations in recruitment and the spawning stock biomass of the Japanese sardine.展开更多
Acute respiratory distress syndrome(ARDS) represents a serious problem in critically ill patients and is associated with in-hospital mortality rates of 33%-52%. Recruitment maneuvers(RMs) are a simple, low-cost, feasi...Acute respiratory distress syndrome(ARDS) represents a serious problem in critically ill patients and is associated with in-hospital mortality rates of 33%-52%. Recruitment maneuvers(RMs) are a simple, low-cost, feasible intervention that can be performed at the bedside in patients with ARDS. RMs are characterized by the application of airway pressure to increase transpulmonary pressure transiently. Once non-aerated lung units are reopened, improvements are observed in respiratory system mechanics, alveolar reaeration on computed tomography, and improvements in gas exchange(functional recruitment). However, the reopening process could lead to vascular compression, which can be associated with overinflation, and gas exchange may not improve as expected(anatomical recruitment). The purpose of this review was to discuss the effects of different RM strategies- sustained inflation, intermittent sighs, and stepwise increases of positive end-expiratory pressure(PEEP) and/or airway inspiratory pressure- on the following parameters: hemodynamics, oxygenation, barotrauma episodes, and lung recruitability through physiological variables and imaging techniques. RMs and PEEP titration are interdependent events for the success of ventilatory management. PEEP should be adjusted on the basis of respiratory system mechanics and oxygenation. Recent systematic reviews and meta-analyses suggest that RMs are associated with lower mortality in patients with ARDS. However, the optimal RM method(i.e., that providing the best balance of benefit and harm) and the effects of RMs on clinical outcome are still under discussion, and further evidence is needed.展开更多
Floodplains are important and distinctive ecosystems around the world,and the recruitment of ichthyoplankton from river to floodplain lakes is crucial to maintain this unique ecosystem.However,this process has not bee...Floodplains are important and distinctive ecosystems around the world,and the recruitment of ichthyoplankton from river to floodplain lakes is crucial to maintain this unique ecosystem.However,this process has not been well documented.In this study,ichthyoplankton were sampled to investigate the details of ichthyoplankton recruitment from the Changjiang(Yangtze)River to the Dongting Lake via a floodway channel,the Songzi River,from May to July in 2013 and 2014.During the study period,41 species of eggs and larvae were sampled.Among the samples,16 were river-lake migratory species(RL),representing 23.5%of the species in the Dongting Lake.In 2013,an estimated 130 million eggs and 3180 million larvae drifted through the sampling section,and in 2014,an estimated 1 060 million eggs and 1040 million larvae drifted through the sampling section.The amount of eggs and larvae of RL reached 3 210 million in 2013 and 1 850 million in 2014,respectively.These results demonstrated the importance of ichthyoplankton recruitment from the river to the lake,as species diversity will decrease sharply without this recruitment.Canonical correspondence analysis(CCA)showed that water temperature and water flow are the two most important factors influencing the spawning activities of fish.To maintain the high fish diversity in the Changjiang floodplain,we suggest to irrigate the channel to increase water discharge and increase the transport of ichthyoplankton from the Changjiang mainstream into the Dongting Lake.展开更多
Background: With the increasing need for high-quality exercise interventions in China, relatively little is known about issues and challenges related to recruitment of older Chinese adults into exercise-based disease ...Background: With the increasing need for high-quality exercise interventions in China, relatively little is known about issues and challenges related to recruitment of older Chinese adults into exercise-based disease prevention interventions. This study aims to describe the recruitment process and outcomes of 2 exercise interventions conducted in Shanghai, China.Methods: Recruitment information was ascertained from 2 community-based randomized controlled trials for 2 exercise interventions, the first designed to improve health outcomes for older women with knee osteoarthritis and the second to study changes in cognitive function in adults with mild cognitive impairment. Results were summarized in terms of recruitment sources, number screened, screening-to-enrollment ratios, and costs.Results: Recruitment was primarily achieved through working with local residential divisions(i.e., neighborhood associations and residential committees). Both studies achieved their planned target number of older adults(45 and 46, respectively) within a 1-year time frame, with a screening-to-randomized ratio of 5:1 and demonstrated excellent retention rates(range 87%–93%) at 6 months. The recruitment cost for the 2studies averaged RMB 189(about USD 30) per initial recruit and RMB 738(about USD 119) per participant randomized. Some major issues encountered during the recruitment process included(1) the use of community neighborhoods to support the conduct of the projects,(2) access to participants, and(3) feasibility.Conclusion: Analysis of the 2 randomized controlled trials has provided valuable insights into the recruitment process and identified resources that can help better planning and recruitment for future interventions. Recommendations aimed at increasing the success of future recruitment efforts are provided.展开更多
This paper was aimed at re-examining the validity of the results from Cahuin et al. (Estuar. Coast. Shelf Sci. 84, 2009) and identifying a model to describe the stock-recruitment relationship of the Peruvian anchoveta...This paper was aimed at re-examining the validity of the results from Cahuin et al. (Estuar. Coast. Shelf Sci. 84, 2009) and identifying a model to describe the stock-recruitment relationship of the Peruvian anchoveta (Eugraulis ringens). Regression analysis was used to determine if density-dependent effects were present. The analysis did not show the existence of any densitydependent effects. It is important to use environmental factors and take observational and process errors into account when attempting to identify density-dependent effects in fish populations. Sea surface temperature (SST) and Southern Oscillation Index (SOI) were used as independent variables to fit the recruitment dynamics of the anchoveta. Both SST and SOI were found to be significantly important parameters in structuring anchoveta dynamics according to Akaike Information Criterion (AIC) and R2 values. The results of this study do not correlate with the findings of Cahuin et al., (2009), where density-dependent effects and the presence of regimes were detected. In conclusion, the recruitment Rt is essentially determined in proportion to spawning stock biomass St, and then environmental factors in year t further change the recruitments. This mechanism is completely same with that for Japanese sardine proposed by Sakuramoto (The Open Fish. Sci. 5, 2012).展开更多
Objective:To evaluate the efficacy and safety of protective lung ventilation strategy combined with lung recruitment maneuver (RM) in the treatment patients with acute respiratory distress syndrome (ARDS).Methods:Tota...Objective:To evaluate the efficacy and safety of protective lung ventilation strategy combined with lung recruitment maneuver (RM) in the treatment patients with acute respiratory distress syndrome (ARDS).Methods:Totally 74 patients with ARDS admitted to the Department of Intensive Care Unit, Changshu Second People's Hospital in Jiangsu Province between September 2010 and June 2013 were selected and randomly divided into lung recruitment group and non-lung recruitment group, and the initial ventilation solution for both groups was synchronized intermittent mandatory ventilation (SIMV). For RM, SIMV mode (pressure control and pressure support) was adopted. Positive end expiratory pressure (PEEP) was increased by 5 cm H2O every time and maintained for 40-50 s before entering the next increasing period, and the peak airway pressure was kept below 45 cm H2O. After PEEP reached the maximum value, it was gradually reduced by 5 cm H2O every time and finally maintained at 15 cm H2O for 10 min.Results:A total of 74 patients with mean age of (49.0±18.6) years old were enrolled, 36 patients were enrolled in lung recruitment maneuver (RM) group and 38 patients were enrolled into non-lung recruitment maneuver (non-RM) group. 44 were male and accounted for 59.5% of all the patients. For the indicators such as PEEP, pressure support (PS), plateau airway pressure (Pplat), peak airway pressure (Ppeak), vital capacity (VC) and fraction of inspired oxygen (FiO2), no statistical differences in the indicators were found between the RM group and non-RM group on D1, D3 and D7 (P>0.05), except that only FiO2 of RM group on D7 was significantly lower than that of non-RM group (47.2±10.0) vs. (52.2±10.5),P<0.05]. For the indicators of blood gas analysis, including pH, arterial oxygen pressure (PaO2), arterial carbon dioxide pressure (PaCO2) and oxygenation index (PaO2/FiO2), PaO2 and PaO2/FiO2 of RM group were significantly higher than those of non-RM group on D7, and the values were [(90.2±16.1) mmHg vs. (76.4±11.3) mmHg,P<0.05] and [(196.5±40.7) mmHg vs. (151.7±37.3) mmHg,P<0.05] respectively. There was no statistical difference in heart rate (HR), cardiac index (CI), central venous pressure (CVP) or mean arterial pressure (MAP) between RM group and non-RM group on D1, D3 and D7 (P>0.05). 28-day mortality, ICU mortality and in-hospital mortality were 25% vs. 28.9%, 25% vs. 26.3% and 36.1% vs. 39.5% respectively between RM group and non-RM group (allP>0.05).Conclusion:Protective lung ventilation strategy combined with lung recruitment maneuver can improve the indicators such as PaO2, FiO2 and PaO2/FiO2 on D7, but failed to improve the final outcomes such as 28-day mortality, ICU mortality and in-hospital mortality.展开更多
Based on the Ricker-type models,the spawning stock-recruitment(S-R)relationship of Portunus trituberculatus was analysed under the impacts of environmental factors(including red tide area(AORT),sea level height(SLH),s...Based on the Ricker-type models,the spawning stock-recruitment(S-R)relationship of Portunus trituberculatus was analysed under the impacts of environmental factors(including red tide area(AORT),sea level height(SLH),sea surface salinity(SSS)and typhoon landing times(TYP))in the northern East China Sea in 2001 and 2014.Besides the traditional Ricker model,two other Ricker-type S-R models were built:Ricker model with ln-linear environmental impact(Ricker-type 2)and Ricker model with ln-quadratic polynomial environmental impact(Ricker-type 3).Results showed that AORT,SLH,SSS and TYP had great influences on the recruitment of P.trituberculatus.When SSS reached 29 and 31,recruitment decreased from 20.7×10^(3) million to 8.3×10^(3) million individuals.In this case,recruitment declined,whereas AORT and TYP increased.Analysis of the S-R model showed that the Akaike information criterion(AIC)value of the traditional Ricker model was 14.619,which remarkably decreased after addition of the environmental factors.Different numbers of environmental factors were added to the Ricker model,and the best result was obtained when four factors were added to the model together.Moreover,Ricker-type 2 model,with the AIC value of-5.307,was better than Ricker-type 3 model(add above four environmental factors at the same time).The findings indicated that the mechanisms by which various environmental factors affect the S-R relationship are different.展开更多
This study research attempts to prohibit privacy and loss of money for individuals and organization by creating a reliable model which can detect the fraud exposure in the online recruitment environments. This researc...This study research attempts to prohibit privacy and loss of money for individuals and organization by creating a reliable model which can detect the fraud exposure in the online recruitment environments. This research presents a major contribution represented in a reliable detection model using ensemble approach based on Random forest classifier to detect Online Recruitment Fraud (ORF). The detection of Online Recruitment Fraud is characterized by other types of electronic fraud detection by its modern and the scarcity of studies on this concept. The researcher proposed the detection model to achieve the objectives of this study. For feature selection, support vector machine method is used and for classification and detection, ensemble classifier using Random Forest is employed. A freely available dataset called Employment Scam Aegean Dataset (EMSCAD) is used to apply the model. Pre-processing step had been applied before the selection and classification adoptions. The results showed an obtained accuracy of 97.41%. Further, the findings presented the main features and important factors in detection purpose include having a company profile feature, having a company logo feature and an industry feature.展开更多
Background:Remnant microhabitats are important for bird habitat selection and plant regeneration in the fragmented habitat.However,empirical information on the consequences of how microhabitat use by birds affects the...Background:Remnant microhabitats are important for bird habitat selection and plant regeneration in the fragmented habitat.However,empirical information on the consequences of how microhabitat use by birds affects the early recruitment of plants is lacking.Methods:In this study,we evaluated whether microhabitat selection by the Black Bulbul(Hypsipetes leucocephalus)(J.F.Gmelin,1789)impacts the early recruitment of the endangered tree species,the Chinese Yew(Taxus chinensis(Pilger)Rehd),in a fragmented forest over a 4-year period(2011–2012,2018–2019).Results:Our results showed the main factors affecting H.leucocephalus microhabitat selection were distance to the nearest T.chinensis mature tree,herb cover and density,leaf litter cover,and vegetation type.Moreover,the results of logistic regression also highlighted the importance of elevation,distance to light gap and roads,tree cover in bird microhabitat selection.Furthermore,the seed emergence rate in microhabitats used by birds did not differ from the natural forest,which was related to five factors of bird microhabitat.The Random Forest model showed that seedling emergence rate was increased with leaf litter cover and distance to fallen dead trees,but decreased in relation to herb cover,slope,and elevation.Conclusion:Our results highlight the importance of remnant microhabitats in fragmented forests for sustaining forest ecology and optimal management.The contribution of microhabitats used by birds to plant recruitment provides insights into how frugivore species contribute to plant regeneration,which should be incorporated in future conservation and management practices of fragmented forests.展开更多
Analysis of stock recruitment (SR) data is most often done by fitting various SR relationship curves to the data. Fish population dynamics data often have stochastic variations and measurement errors, which usually re...Analysis of stock recruitment (SR) data is most often done by fitting various SR relationship curves to the data. Fish population dynamics data often have stochastic variations and measurement errors, which usually result in a biased regression analysis. This paper presents a robust regression method, least median of squared orthogonal distance (LMD), which is insensitive to abnormal values in the dependent and independent variables in a regression analysis. Outliers that have significantly different variance from the rest of the data can be identified in a residual analysis. Then, the least squares (LS) method is applied to the SR data with defined outliers being down weighted. The application of LMD and LMD based Reweighted Least Squares (RLS) method to simulated and real fisheries SR data is explored.展开更多
In semi-arid lands,vegetation is distributed in shrub patches immersed in a less vegetated interpatch matrix.Grazing affects perennial grass seed bank through a decrease in seed rain and an increase in seed predation ...In semi-arid lands,vegetation is distributed in shrub patches immersed in a less vegetated interpatch matrix.Grazing affects perennial grass seed bank through a decrease in seed rain and an increase in seed predation and soil compaction.Nevertheless,some species with anchorage mechanisms in their seeds might overcome this,such as Nassella tenuis(Phil.)Barkworth.This is an important species in grazing paddocks because it has an intermediate palatability and its relatively tolerant to grazing.These characteristics allow N.tenuis to increase its abundance in grazed sites.Our objective was to assess how grazing affects the key palatable species from seeds to seedlings:i.e.,seed rain,soil seed bank,and seedling recruitment in different microsites along a windward-leeward transect across shrub canopy.We hypothesized that:(1)the negative effects of grazing on N.tenuis fructification are reflected in its seed rain,soil seed bank,and seedling recruitment,especially in interpatches;(2)Nassella tenuis seed rain reduction,soil compaction by cattle in grazed sites,and removal of seeds by wind decrease its soil seed bank,especially in microsites exposed to the predominant wind;and(3)the decrease in N.tenuis soil seed bank and cover increase in annual species in grazed sites have negative effects on its seedling recruitment,especially in microsites exposed to predominant wind.We placed seed traps,collected soil samples,and monitored seedling recruitment in different locations around shrub canopy to address our hypotheses.Also,we established a manipulative experiment in which we sow N.tenuis seeds and followed its recruitment in different microsites.We compared the seed rain,soil seed bank,natural seedling recruitment,and sown seeds recruitment of N.tenuis between grazed and ungrazed sites.We analyzed differences between microsites along a windward-leeward transect across shrubs patches.Seed rain and soil seed bank had the same density in patches and interpatches both in ungrazed and grazed sites.But seed rain was higher,and soil seed bank was lower in ungrazed sites than in grazed sites.Almost all under-canopy microsites showed greater soil seed bank abundance and natural seedling recruitment in ungrazed sites.Sown seeds recruitment was the same between grazed and ungrazed sites,but it showed protective effects of shrubs in leeward microsites under grazed sites.As a conclusion,seed rain and soil seed bank are complementary under grazed sites.展开更多
Studies presenting long-term observations of the recruitment and mobility of large wood in mountain watercourses are scarce,but they can considerably contribute to the knowledge of river/riparian forest interactions a...Studies presenting long-term observations of the recruitment and mobility of large wood in mountain watercourses are scarce,but they can considerably contribute to the knowledge of river/riparian forest interactions and the assessment of flood hazard resulting from wood mobility during floods.Widespread dieback of riparian forest along the headwater course of Kamienica Stream in the Polish Carpathians,caused by bark beetle infestation of spruce trees,has raised concerns about potential increases of large wood recruitment to the stream and of the flood hazard to downstream valley reaches.In October 2009,429 trees growing along three sections of the stream were tagged with numbered metal plates and monitored over 10 years to determine the timing and causes of their delivery to the channel and the lengths of their displacement during individual flood events.Moreover,in 2012 the mode of location of wood deposits and a degree of wood decay were determined in the second-to fourth-order stream reaches.The monitoring of tagged trees indicated that trees were recruited to the channel during highintensity meteorological and hydrological events,mostly as a result of bank erosion during floods or windthrow.With 22%of tagged trees recruited to the channel during 10 years,the rate of turnover of the riparian trees was estimated at 45 years.As the riparian area is overgrown with trees with ages up to^160 years,the rate evidences substantial intensification of large wood recruitment to the channel in the recent period.Results of large wood inventory and the 10-year-long monitoring of tagged trees indicated variable mobility of large wood along the upper course of the stream.Wood mobility was negligible in the second-order stream reach,very small in the third-order reach,and greater,but still limited in the fourth-order reach.Wood is transported longer distances only during major floods.However,the advanced state of decay of most pieces leads to their disintegration during floods,precluding distant transport.Thus,large wood retained in the upper stream course does not constitute an important flood hazard to downstream,inhabited valley reaches.展开更多
Mobile crowdsensing(MCS) has become an emerging paradigm to solve urban sensing problems by leveraging the ubiquitous sensing capabilities of the crowd. One critical issue in MCS is how to recruit users to fulfill mor...Mobile crowdsensing(MCS) has become an emerging paradigm to solve urban sensing problems by leveraging the ubiquitous sensing capabilities of the crowd. One critical issue in MCS is how to recruit users to fulfill more sensing tasks with budget restriction, while sharing data among tasks can be a credible way to improve the efficiency. The data-sharing based user recruitment problem under budget constraint in a realistic scenario is studied, where multiple tasks require homogeneous data but have various spatio-temporal execution ranges, meanwhile users suffer from uncertain future positions. The problem is formulated in a manner of probability by predicting user mobility, then a dynamic user recruitment algorithm is proposed to solve it. In the algorithm a greedy-adding-and-substitution(GAS) heuristic is repeatedly implemented by updating user mobility prediction in each time slot to gradually achieve the final solution. Extensive simulations are conducted using a real-world taxi trace dataset, and the results demonstrate that the approach can fulfill more tasks than existing methods.展开更多
Riparian vegetation is known to affect the flood flow and the riparian environment, and it is important for river engineers to know the vegetation dynamics in river. Despite a number of researches have been performed ...Riparian vegetation is known to affect the flood flow and the riparian environment, and it is important for river engineers to know the vegetation dynamics in river. Despite a number of researches have been performed for vegetation dynamics, the mechanism of initial vegetation recruitment is still not clear. In this study, two field surveys by using Unmanned Aerial Vehicle (UAV) remote sensing, UAV aerial photographs analysis and a numerical simulation were conducted to detect the location of initial vegetation recruitment and explore its relationship with hydrology and river morphology. The initial vegetation recruitment was identified by comparing vegetation distributions before and after vegetation germination. Most of the initial vegetation recruitment locations were found either along dunes on sandbar or along the wet/dry rotational area of shore bank. Results of the aerial photographs analysis showed that the initial vegetation recruitment occurred at the downstream side of crest of dunes. As for the vegetation recruitment zone located along shore bank, the relative elevation of different recruitment zones is almost same, and the mean value of the relative elevation is around 0.33 m. With the comparison of the contour map of river morphology and the initial vegetation recruitment zone, the shape of initial vegetation recruitment zone is positively consistent with the shape of river morphology distribution. The results of numerical analysis show that the initial vegetation recruitment zone located along shore bank experienced intermediate flood pulse. The inundation frequencies during seed dispersal and germination period for the internal and external boundaries of vegetation recruitment zone are 23.87% and 6.2%, respectively.展开更多
At present, the fishery of Litopenaeus vannamei continues overexploited in the Gulf of Tehuantepec (GT), Mexico. From the available literature it was demonstrated that marine closure systems implemented in GT have not...At present, the fishery of Litopenaeus vannamei continues overexploited in the Gulf of Tehuantepec (GT), Mexico. From the available literature it was demonstrated that marine closure systems implemented in GT have not worked adequately since 1993, because these are completely protecting marine recruitment seasons, and reproductive seasons were only partially considered to protect. Due to these problems, new marine closure systems were proposed in the literature, but they were not accepted by fishermen from GT because they did not include marine and lagoon recruitment information. For this reason, in this study both recruitment types were analyzed with estimations on the recruitment age (RA), and its relationship with total length and weight. To the Cabeza de Toro la Joya Buenavista lagoon system (CTJB-LS), it was concluded that young recruits migration toward outside CTJB-LS elapsed between 3 and 5-m-olds, with the highest recruit flow in 4-m-olds. Thus, this last age was called the RA of L. vannamei (at 106 mm). Maximum marine recruitment ranked from June to July, and maximum reproductive seasons were in October. In both recruitment seasons it was observed that biomass production was different. In marine season RA recorded 8.4 g more than lagoon season at the same size. Results were used in order to discus about atarraya nets uses, and to propose the implementation of a lagoon closure during July inside lagoon systems located in GT. With this proposal artisanal fishermen will be allowed to use atarraya nets with mesh opening of 25.4 mm during June, and they will obtain a good biomass production level as economic support.Additionally, with new marine closure systems shrimp reproductive seasons will be protected (from July to November).展开更多
The impact on seedling recruitment by fallen wood of A. fabri forest in Tibet Sygera Mountain was studied. The results showed that regenerated seedlings on fallen wood roughly showed normal distribution,and there were...The impact on seedling recruitment by fallen wood of A. fabri forest in Tibet Sygera Mountain was studied. The results showed that regenerated seedlings on fallen wood roughly showed normal distribution,and there were more regenerated seedlings in the middle of fallen wood,while regenerated seedlings were fewer at two ends. Fallen wood at level IV had the most regenerated seedlings,followed by level-III fallen wood,and regenerated seedlings were the fewest on fallen wood at level V. The number and species of regenerated seedling on and around fallen wood on the west slope were more than that on the east slope. With the improvement of decomposition level,regenerated seedling per unit area firstly increased and then decreased,but the number of regenerated seedling on and around fallen wood was far more than that in woodland.展开更多
基金Supported by the Science and Technology Program of Guangzhou(No.201803010066)the High-level Hospital Construction Project,Zhongshan Ophthalmic Center,Sun Yat-sen University(No.303010202).
文摘AIM:To explore the factors influencing individuals’willingness to participate in ophthalmic clinical trials.METHODS:A questionnaire survey was conducted from January to April 2021 among patients and their family members at Zhongshan Ophthalmic Center,Sun Yat-sen University,in Guangzhou,China.The survey gathered data on respondents’willingness,demographic and socioeconomic profiles,as well as their reasons and concerns regarding engagement in clinical trials.RESULTS:Of the 1078 residents surveyed(mean age 31.2±13.1y;65.8%females)in Guangzhou,749(69.5%)expressed a willingness to participate in future ophthalmic clinical trials.Specific characteristics associated with greater willingness included a younger age,lower annual income,higher education,prior participation experience,previous ophthalmic treatment,and a better understanding of clinical trials.With the exception of age,these characteristics were significantly linked to a higher willingness.The primary barrier to participation,expressed by 64.8%of those willing and 54.4%of those unwilling,was“Uncertain efficacy”.In terms of motivations,the willing group ranked“Better therapeutic benefits”(35.0%),“Professional monitoring”(34.3%),and“Trust in healthcare professionals”(33.1%)as their top three reasons,whereas the unwilling participants indicated“Full comprehension of the protocol”(46.2%)as the key facilitator.CONCLUSION:This study reveals a substantial willingness to participate in ophthalmic clinical trials and demonstrates the predictive role of demographic and socioeconomic factors.Variations in motivators and concerns between willing and unwilling participants highlight the significance of tailored recruitment strategies.Importantly,the need for and trust in healthcare professionals stand out as powerful motivations,underscoring the importance of enhancing physician-patient relationships,adopting patient-centered communication approaches,and addressing individualized needs to improve accrual rates.
基金the Medical Scientific Research Foundation of Guangdong Province,No.A2017045。
文摘BACKGROUND Alveolar recruitment maneuvers(ARMs)may lead to transient hypotension,but the clinical characteristics of this induced hypotension are poorly understood.We investigated the characteristics of ARM-related hypotension in patients who underwent laparoscopic colorectal cancer resection.AIM To investigate the characteristics of ARM-related hypotension in patients who underwent laparoscopic colorectal cancer resection.METHODS This was a secondary analysis of the PROtective Ventilation using Open Lung approach Or Not trial and included 140 subjects.An ARM was repeated every 30 min during intraoperative mechanical ventilation.The primary endpoint was ARM-related hypotension,defined as a mean arterial pressure(MAP)<60 mmHg during an ARM or within 5 min after an ARM.The risk factors for hypotension were identified.The peri-ARM changes in blood pressure were analyzed for the first three ARMs(ARM_(1,2,3))and the last ARM(ARMl_(ast)).RESULTS Thirty-four subjects(24.3%)developed ARM-related hypotension.Of all 1027 ARMs,37(3.61%)induced hypotension.More ARMs under nonpneumoperitoneum(33/349,9.46%)than under pneumoperitoneum conditions(4/678,0.59%)induced hypotension(P<0.01).The incidence of hypotension was higher at ARM_(1)points than at non-ARM_(1)points(18/135,13.3%vs 19/892,2.1%;P<0.01).The median percentage decrease in the MAP at ARM1 was 14%.Age≥74 years,blood loss≥150 mL and peak inspiratory pressure under pneumoperitoneum<24 cm H_(2)O were risk factors for ARM-related hypotension.CONCLUSION When the ARM was repeated intraoperatively,a quarter of subjects developed ARM-related hypotension,but only 3.61%of ARMs induced hypotension.ARM-related hypotension most occurred in a hemodynamically unstable state or a hypovolemic state,and in elderly subjects.Fortunately,ARMs that were performed under pneumoperitoneum conditions had less impact on blood pressure.
文摘Enrolling in clinical trials could be time-sensitive and time-demanding tasks for the research site, especially if it is a private research organization compared to the research conducted at an academic or medical center. Every study differs in various aspects, such as phases, study indication, eligibility criteria, etc. In terms of meeting the enrollment deadline, typically, the study indication and availability of the patient’s population at the geographical area of the research site would decide if the trial could be time-consuming. Patient recruitment and retention are critical for the success of every clinical trial;however, worldwide, this area is facing tremendous pressure and challenges. Globally 55% of clinical trials terminated due to low recruitment, with an average enrollment success rate of 40% for Phase III and IV trials. Over 80% of clinical trial attempts fail to enroll, extending the study and adding new study sites. In the United States, more than 80% of clinical trials fail to achieve targeted patient enrollment, and 30% of study participants discontinue participation. This article reviewed various factors hindering clinical trial recruitment and retention and suggested strategies to make the research site successful.
文摘Concrete action on diversity and inclusion(D&I)is critical to companies’value creation and brand.Companies that intentionally fail to attract and retain a diverse talent pool will struggle to innovate,compete,and prosper.The advantages of a diverse and inclusive workplace include the reduction of homogenous thinking and an increase in novel ideas and perspectives due to the wealth of talent from diverse backgrounds.Previous studies have focused on the benefits of corporate D&I from a corporate perspective;however,there is scant research on the impact of corporate D&I from employees’perspectives.Resultingly,this study,through an online questionnaire,proposes to examine the impact of employer brand D&I on potential employees in online recruitment channels from the perspective of potential employees.The study results indicate that most Chinese companies still exhibit low levels of D&I during recruitment.This study also included an empirical analysis of 267 valid samples,which showed that:(1)the D&I of employer brand perceptions positively impact job search intentions,behaviour,and decision making.(2)Companies’D&I has the most significant influence on job seekers’decision making,followed by behavioural influence and cognitive influence.(3)The type of job seeker plays a moderating role in the relationship between employer brand perception and job search intention,behaviour,and decision making.(4)Online recruitment’s increasing popularity amplifies employer branding’s effect.Based on the findings,this study suggests how companies can use D&I branding strategies to attract quality talent and increase job seekers’job search intentions.
文摘This study developed a recruitment forecasting model based on a new concept of the stock recruitment relationship. No density-dependent effect in the relationship was assumed in the model, which showed that fluctuations in recruitment and spawning stock biomass of Japanese sardine in the northwestern Pacific can be explained mainly by environmental factors and the effects of fishing. The February Arctic Oscillation (AO) and sea surface temperature over the southern area of the Kuroshio Extension (30 - 35°N and 145 - 180°E;KEST) were used as the environmental factors. The recruitment forecasting model is proposed: The values for recruitment (), spawning stock biomass, (), in year t, forecast by this model accurately reproduced those estimated by tuning virtual population analysis (VPA), and the pattern of variability in the stock recruitment relationship was also reproduced well. In conclusion, a density-dependent effect does not necessarily have to be included to explain the large variations in recruitment and the spawning stock biomass of the Japanese sardine.
基金Supported by Brazilian Council for Scientific and Technological Development(CNPq),Carlos Chagas Filho Rio de Janeiro State Research Foundation(FAPERJ),Department of Science and Technology(DECIT)/Brazilian Ministry of HealthCoordination for the Improvement of Higher Level Personnel(CAPES)
文摘Acute respiratory distress syndrome(ARDS) represents a serious problem in critically ill patients and is associated with in-hospital mortality rates of 33%-52%. Recruitment maneuvers(RMs) are a simple, low-cost, feasible intervention that can be performed at the bedside in patients with ARDS. RMs are characterized by the application of airway pressure to increase transpulmonary pressure transiently. Once non-aerated lung units are reopened, improvements are observed in respiratory system mechanics, alveolar reaeration on computed tomography, and improvements in gas exchange(functional recruitment). However, the reopening process could lead to vascular compression, which can be associated with overinflation, and gas exchange may not improve as expected(anatomical recruitment). The purpose of this review was to discuss the effects of different RM strategies- sustained inflation, intermittent sighs, and stepwise increases of positive end-expiratory pressure(PEEP) and/or airway inspiratory pressure- on the following parameters: hemodynamics, oxygenation, barotrauma episodes, and lung recruitability through physiological variables and imaging techniques. RMs and PEEP titration are interdependent events for the success of ventilatory management. PEEP should be adjusted on the basis of respiratory system mechanics and oxygenation. Recent systematic reviews and meta-analyses suggest that RMs are associated with lower mortality in patients with ARDS. However, the optimal RM method(i.e., that providing the best balance of benefit and harm) and the effects of RMs on clinical outcome are still under discussion, and further evidence is needed.
基金Supported by the National Key Research and Development Program of China(No.2016YFC0402005)the Three Gorges Project EcoEnvironmental Monitoring System(No.JJ [2017]-011)+1 种基金the National Natural Science Foundation of China(No.NSFC31400359)the China Three Gorges Corporation(No.0704097)
文摘Floodplains are important and distinctive ecosystems around the world,and the recruitment of ichthyoplankton from river to floodplain lakes is crucial to maintain this unique ecosystem.However,this process has not been well documented.In this study,ichthyoplankton were sampled to investigate the details of ichthyoplankton recruitment from the Changjiang(Yangtze)River to the Dongting Lake via a floodway channel,the Songzi River,from May to July in 2013 and 2014.During the study period,41 species of eggs and larvae were sampled.Among the samples,16 were river-lake migratory species(RL),representing 23.5%of the species in the Dongting Lake.In 2013,an estimated 130 million eggs and 3180 million larvae drifted through the sampling section,and in 2014,an estimated 1 060 million eggs and 1040 million larvae drifted through the sampling section.The amount of eggs and larvae of RL reached 3 210 million in 2013 and 1 850 million in 2014,respectively.These results demonstrated the importance of ichthyoplankton recruitment from the river to the lake,as species diversity will decrease sharply without this recruitment.Canonical correspondence analysis(CCA)showed that water temperature and water flow are the two most important factors influencing the spawning activities of fish.To maintain the high fish diversity in the Changjiang floodplain,we suggest to irrigate the channel to increase water discharge and increase the transport of ichthyoplankton from the Changjiang mainstream into the Dongting Lake.
基金supported by the Shanghai City Committee of Science and Technology Key Project (No. 12490503200)the National Natural Science Foundation of China (No. 81572213, No. 11372194)
文摘Background: With the increasing need for high-quality exercise interventions in China, relatively little is known about issues and challenges related to recruitment of older Chinese adults into exercise-based disease prevention interventions. This study aims to describe the recruitment process and outcomes of 2 exercise interventions conducted in Shanghai, China.Methods: Recruitment information was ascertained from 2 community-based randomized controlled trials for 2 exercise interventions, the first designed to improve health outcomes for older women with knee osteoarthritis and the second to study changes in cognitive function in adults with mild cognitive impairment. Results were summarized in terms of recruitment sources, number screened, screening-to-enrollment ratios, and costs.Results: Recruitment was primarily achieved through working with local residential divisions(i.e., neighborhood associations and residential committees). Both studies achieved their planned target number of older adults(45 and 46, respectively) within a 1-year time frame, with a screening-to-randomized ratio of 5:1 and demonstrated excellent retention rates(range 87%–93%) at 6 months. The recruitment cost for the 2studies averaged RMB 189(about USD 30) per initial recruit and RMB 738(about USD 119) per participant randomized. Some major issues encountered during the recruitment process included(1) the use of community neighborhoods to support the conduct of the projects,(2) access to participants, and(3) feasibility.Conclusion: Analysis of the 2 randomized controlled trials has provided valuable insights into the recruitment process and identified resources that can help better planning and recruitment for future interventions. Recommendations aimed at increasing the success of future recruitment efforts are provided.
文摘This paper was aimed at re-examining the validity of the results from Cahuin et al. (Estuar. Coast. Shelf Sci. 84, 2009) and identifying a model to describe the stock-recruitment relationship of the Peruvian anchoveta (Eugraulis ringens). Regression analysis was used to determine if density-dependent effects were present. The analysis did not show the existence of any densitydependent effects. It is important to use environmental factors and take observational and process errors into account when attempting to identify density-dependent effects in fish populations. Sea surface temperature (SST) and Southern Oscillation Index (SOI) were used as independent variables to fit the recruitment dynamics of the anchoveta. Both SST and SOI were found to be significantly important parameters in structuring anchoveta dynamics according to Akaike Information Criterion (AIC) and R2 values. The results of this study do not correlate with the findings of Cahuin et al., (2009), where density-dependent effects and the presence of regimes were detected. In conclusion, the recruitment Rt is essentially determined in proportion to spawning stock biomass St, and then environmental factors in year t further change the recruitments. This mechanism is completely same with that for Japanese sardine proposed by Sakuramoto (The Open Fish. Sci. 5, 2012).
文摘Objective:To evaluate the efficacy and safety of protective lung ventilation strategy combined with lung recruitment maneuver (RM) in the treatment patients with acute respiratory distress syndrome (ARDS).Methods:Totally 74 patients with ARDS admitted to the Department of Intensive Care Unit, Changshu Second People's Hospital in Jiangsu Province between September 2010 and June 2013 were selected and randomly divided into lung recruitment group and non-lung recruitment group, and the initial ventilation solution for both groups was synchronized intermittent mandatory ventilation (SIMV). For RM, SIMV mode (pressure control and pressure support) was adopted. Positive end expiratory pressure (PEEP) was increased by 5 cm H2O every time and maintained for 40-50 s before entering the next increasing period, and the peak airway pressure was kept below 45 cm H2O. After PEEP reached the maximum value, it was gradually reduced by 5 cm H2O every time and finally maintained at 15 cm H2O for 10 min.Results:A total of 74 patients with mean age of (49.0±18.6) years old were enrolled, 36 patients were enrolled in lung recruitment maneuver (RM) group and 38 patients were enrolled into non-lung recruitment maneuver (non-RM) group. 44 were male and accounted for 59.5% of all the patients. For the indicators such as PEEP, pressure support (PS), plateau airway pressure (Pplat), peak airway pressure (Ppeak), vital capacity (VC) and fraction of inspired oxygen (FiO2), no statistical differences in the indicators were found between the RM group and non-RM group on D1, D3 and D7 (P>0.05), except that only FiO2 of RM group on D7 was significantly lower than that of non-RM group (47.2±10.0) vs. (52.2±10.5),P<0.05]. For the indicators of blood gas analysis, including pH, arterial oxygen pressure (PaO2), arterial carbon dioxide pressure (PaCO2) and oxygenation index (PaO2/FiO2), PaO2 and PaO2/FiO2 of RM group were significantly higher than those of non-RM group on D7, and the values were [(90.2±16.1) mmHg vs. (76.4±11.3) mmHg,P<0.05] and [(196.5±40.7) mmHg vs. (151.7±37.3) mmHg,P<0.05] respectively. There was no statistical difference in heart rate (HR), cardiac index (CI), central venous pressure (CVP) or mean arterial pressure (MAP) between RM group and non-RM group on D1, D3 and D7 (P>0.05). 28-day mortality, ICU mortality and in-hospital mortality were 25% vs. 28.9%, 25% vs. 26.3% and 36.1% vs. 39.5% respectively between RM group and non-RM group (allP>0.05).Conclusion:Protective lung ventilation strategy combined with lung recruitment maneuver can improve the indicators such as PaO2, FiO2 and PaO2/FiO2 on D7, but failed to improve the final outcomes such as 28-day mortality, ICU mortality and in-hospital mortality.
基金The National Key Research and Development Program of China under contract Nos 2017YFA0604902 and 2019YFD0901304the Public Welfare Technology Application Research Project of Zhejiang under contract No.LGN21C190009。
文摘Based on the Ricker-type models,the spawning stock-recruitment(S-R)relationship of Portunus trituberculatus was analysed under the impacts of environmental factors(including red tide area(AORT),sea level height(SLH),sea surface salinity(SSS)and typhoon landing times(TYP))in the northern East China Sea in 2001 and 2014.Besides the traditional Ricker model,two other Ricker-type S-R models were built:Ricker model with ln-linear environmental impact(Ricker-type 2)and Ricker model with ln-quadratic polynomial environmental impact(Ricker-type 3).Results showed that AORT,SLH,SSS and TYP had great influences on the recruitment of P.trituberculatus.When SSS reached 29 and 31,recruitment decreased from 20.7×10^(3) million to 8.3×10^(3) million individuals.In this case,recruitment declined,whereas AORT and TYP increased.Analysis of the S-R model showed that the Akaike information criterion(AIC)value of the traditional Ricker model was 14.619,which remarkably decreased after addition of the environmental factors.Different numbers of environmental factors were added to the Ricker model,and the best result was obtained when four factors were added to the model together.Moreover,Ricker-type 2 model,with the AIC value of-5.307,was better than Ricker-type 3 model(add above four environmental factors at the same time).The findings indicated that the mechanisms by which various environmental factors affect the S-R relationship are different.
文摘This study research attempts to prohibit privacy and loss of money for individuals and organization by creating a reliable model which can detect the fraud exposure in the online recruitment environments. This research presents a major contribution represented in a reliable detection model using ensemble approach based on Random forest classifier to detect Online Recruitment Fraud (ORF). The detection of Online Recruitment Fraud is characterized by other types of electronic fraud detection by its modern and the scarcity of studies on this concept. The researcher proposed the detection model to achieve the objectives of this study. For feature selection, support vector machine method is used and for classification and detection, ensemble classifier using Random Forest is employed. A freely available dataset called Employment Scam Aegean Dataset (EMSCAD) is used to apply the model. Pre-processing step had been applied before the selection and classification adoptions. The results showed an obtained accuracy of 97.41%. Further, the findings presented the main features and important factors in detection purpose include having a company profile feature, having a company logo feature and an industry feature.
基金This study was supported by the National Natural Science Foundation of China(Grant No.31700468)the Natural Science Foundation of Jiangsu Province(Grant No.BK2017636).
文摘Background:Remnant microhabitats are important for bird habitat selection and plant regeneration in the fragmented habitat.However,empirical information on the consequences of how microhabitat use by birds affects the early recruitment of plants is lacking.Methods:In this study,we evaluated whether microhabitat selection by the Black Bulbul(Hypsipetes leucocephalus)(J.F.Gmelin,1789)impacts the early recruitment of the endangered tree species,the Chinese Yew(Taxus chinensis(Pilger)Rehd),in a fragmented forest over a 4-year period(2011–2012,2018–2019).Results:Our results showed the main factors affecting H.leucocephalus microhabitat selection were distance to the nearest T.chinensis mature tree,herb cover and density,leaf litter cover,and vegetation type.Moreover,the results of logistic regression also highlighted the importance of elevation,distance to light gap and roads,tree cover in bird microhabitat selection.Furthermore,the seed emergence rate in microhabitats used by birds did not differ from the natural forest,which was related to five factors of bird microhabitat.The Random Forest model showed that seedling emergence rate was increased with leaf litter cover and distance to fallen dead trees,but decreased in relation to herb cover,slope,and elevation.Conclusion:Our results highlight the importance of remnant microhabitats in fragmented forests for sustaining forest ecology and optimal management.The contribution of microhabitats used by birds to plant recruitment provides insights into how frugivore species contribute to plant regeneration,which should be incorporated in future conservation and management practices of fragmented forests.
文摘Analysis of stock recruitment (SR) data is most often done by fitting various SR relationship curves to the data. Fish population dynamics data often have stochastic variations and measurement errors, which usually result in a biased regression analysis. This paper presents a robust regression method, least median of squared orthogonal distance (LMD), which is insensitive to abnormal values in the dependent and independent variables in a regression analysis. Outliers that have significantly different variance from the rest of the data can be identified in a residual analysis. Then, the least squares (LS) method is applied to the SR data with defined outliers being down weighted. The application of LMD and LMD based Reweighted Least Squares (RLS) method to simulated and real fisheries SR data is explored.
基金supported by the National University of Río Negro(PI 40-C-654,PI 40-C-873)。
文摘In semi-arid lands,vegetation is distributed in shrub patches immersed in a less vegetated interpatch matrix.Grazing affects perennial grass seed bank through a decrease in seed rain and an increase in seed predation and soil compaction.Nevertheless,some species with anchorage mechanisms in their seeds might overcome this,such as Nassella tenuis(Phil.)Barkworth.This is an important species in grazing paddocks because it has an intermediate palatability and its relatively tolerant to grazing.These characteristics allow N.tenuis to increase its abundance in grazed sites.Our objective was to assess how grazing affects the key palatable species from seeds to seedlings:i.e.,seed rain,soil seed bank,and seedling recruitment in different microsites along a windward-leeward transect across shrub canopy.We hypothesized that:(1)the negative effects of grazing on N.tenuis fructification are reflected in its seed rain,soil seed bank,and seedling recruitment,especially in interpatches;(2)Nassella tenuis seed rain reduction,soil compaction by cattle in grazed sites,and removal of seeds by wind decrease its soil seed bank,especially in microsites exposed to the predominant wind;and(3)the decrease in N.tenuis soil seed bank and cover increase in annual species in grazed sites have negative effects on its seedling recruitment,especially in microsites exposed to predominant wind.We placed seed traps,collected soil samples,and monitored seedling recruitment in different locations around shrub canopy to address our hypotheses.Also,we established a manipulative experiment in which we sow N.tenuis seeds and followed its recruitment in different microsites.We compared the seed rain,soil seed bank,natural seedling recruitment,and sown seeds recruitment of N.tenuis between grazed and ungrazed sites.We analyzed differences between microsites along a windward-leeward transect across shrubs patches.Seed rain and soil seed bank had the same density in patches and interpatches both in ungrazed and grazed sites.But seed rain was higher,and soil seed bank was lower in ungrazed sites than in grazed sites.Almost all under-canopy microsites showed greater soil seed bank abundance and natural seedling recruitment in ungrazed sites.Sown seeds recruitment was the same between grazed and ungrazed sites,but it showed protective effects of shrubs in leeward microsites under grazed sites.As a conclusion,seed rain and soil seed bank are complementary under grazed sites.
基金financed by the statutory funds of the Institute of Nature Conservation,Polish Academy of Sciencesby the project FLORIST(Flood risk on the northern foothills of the Tatra MountainsPSPB no 153/2010)supported by a grant from Switzerland through the Swiss Contribution to the Enlarged European Union。
文摘Studies presenting long-term observations of the recruitment and mobility of large wood in mountain watercourses are scarce,but they can considerably contribute to the knowledge of river/riparian forest interactions and the assessment of flood hazard resulting from wood mobility during floods.Widespread dieback of riparian forest along the headwater course of Kamienica Stream in the Polish Carpathians,caused by bark beetle infestation of spruce trees,has raised concerns about potential increases of large wood recruitment to the stream and of the flood hazard to downstream valley reaches.In October 2009,429 trees growing along three sections of the stream were tagged with numbered metal plates and monitored over 10 years to determine the timing and causes of their delivery to the channel and the lengths of their displacement during individual flood events.Moreover,in 2012 the mode of location of wood deposits and a degree of wood decay were determined in the second-to fourth-order stream reaches.The monitoring of tagged trees indicated that trees were recruited to the channel during highintensity meteorological and hydrological events,mostly as a result of bank erosion during floods or windthrow.With 22%of tagged trees recruited to the channel during 10 years,the rate of turnover of the riparian trees was estimated at 45 years.As the riparian area is overgrown with trees with ages up to^160 years,the rate evidences substantial intensification of large wood recruitment to the channel in the recent period.Results of large wood inventory and the 10-year-long monitoring of tagged trees indicated variable mobility of large wood along the upper course of the stream.Wood mobility was negligible in the second-order stream reach,very small in the third-order reach,and greater,but still limited in the fourth-order reach.Wood is transported longer distances only during major floods.However,the advanced state of decay of most pieces leads to their disintegration during floods,precluding distant transport.Thus,large wood retained in the upper stream course does not constitute an important flood hazard to downstream,inhabited valley reaches.
基金Supported by the National Natural Science Foundation of China(No.61472402,61472404,61732017,61501125,61502457)
文摘Mobile crowdsensing(MCS) has become an emerging paradigm to solve urban sensing problems by leveraging the ubiquitous sensing capabilities of the crowd. One critical issue in MCS is how to recruit users to fulfill more sensing tasks with budget restriction, while sharing data among tasks can be a credible way to improve the efficiency. The data-sharing based user recruitment problem under budget constraint in a realistic scenario is studied, where multiple tasks require homogeneous data but have various spatio-temporal execution ranges, meanwhile users suffer from uncertain future positions. The problem is formulated in a manner of probability by predicting user mobility, then a dynamic user recruitment algorithm is proposed to solve it. In the algorithm a greedy-adding-and-substitution(GAS) heuristic is repeatedly implemented by updating user mobility prediction in each time slot to gradually achieve the final solution. Extensive simulations are conducted using a real-world taxi trace dataset, and the results demonstrate that the approach can fulfill more tasks than existing methods.
文摘Riparian vegetation is known to affect the flood flow and the riparian environment, and it is important for river engineers to know the vegetation dynamics in river. Despite a number of researches have been performed for vegetation dynamics, the mechanism of initial vegetation recruitment is still not clear. In this study, two field surveys by using Unmanned Aerial Vehicle (UAV) remote sensing, UAV aerial photographs analysis and a numerical simulation were conducted to detect the location of initial vegetation recruitment and explore its relationship with hydrology and river morphology. The initial vegetation recruitment was identified by comparing vegetation distributions before and after vegetation germination. Most of the initial vegetation recruitment locations were found either along dunes on sandbar or along the wet/dry rotational area of shore bank. Results of the aerial photographs analysis showed that the initial vegetation recruitment occurred at the downstream side of crest of dunes. As for the vegetation recruitment zone located along shore bank, the relative elevation of different recruitment zones is almost same, and the mean value of the relative elevation is around 0.33 m. With the comparison of the contour map of river morphology and the initial vegetation recruitment zone, the shape of initial vegetation recruitment zone is positively consistent with the shape of river morphology distribution. The results of numerical analysis show that the initial vegetation recruitment zone located along shore bank experienced intermediate flood pulse. The inundation frequencies during seed dispersal and germination period for the internal and external boundaries of vegetation recruitment zone are 23.87% and 6.2%, respectively.
文摘At present, the fishery of Litopenaeus vannamei continues overexploited in the Gulf of Tehuantepec (GT), Mexico. From the available literature it was demonstrated that marine closure systems implemented in GT have not worked adequately since 1993, because these are completely protecting marine recruitment seasons, and reproductive seasons were only partially considered to protect. Due to these problems, new marine closure systems were proposed in the literature, but they were not accepted by fishermen from GT because they did not include marine and lagoon recruitment information. For this reason, in this study both recruitment types were analyzed with estimations on the recruitment age (RA), and its relationship with total length and weight. To the Cabeza de Toro la Joya Buenavista lagoon system (CTJB-LS), it was concluded that young recruits migration toward outside CTJB-LS elapsed between 3 and 5-m-olds, with the highest recruit flow in 4-m-olds. Thus, this last age was called the RA of L. vannamei (at 106 mm). Maximum marine recruitment ranked from June to July, and maximum reproductive seasons were in October. In both recruitment seasons it was observed that biomass production was different. In marine season RA recorded 8.4 g more than lagoon season at the same size. Results were used in order to discus about atarraya nets uses, and to propose the implementation of a lagoon closure during July inside lagoon systems located in GT. With this proposal artisanal fishermen will be allowed to use atarraya nets with mesh opening of 25.4 mm during June, and they will obtain a good biomass production level as economic support.Additionally, with new marine closure systems shrimp reproductive seasons will be protected (from July to November).
基金Supported by the National Natural Science Foundation of China(31460122)Excellent Teaching Team Project in Tibet Colleges and Universities:Plateau Forest Cultivation and Management Team(2017)
文摘The impact on seedling recruitment by fallen wood of A. fabri forest in Tibet Sygera Mountain was studied. The results showed that regenerated seedlings on fallen wood roughly showed normal distribution,and there were more regenerated seedlings in the middle of fallen wood,while regenerated seedlings were fewer at two ends. Fallen wood at level IV had the most regenerated seedlings,followed by level-III fallen wood,and regenerated seedlings were the fewest on fallen wood at level V. The number and species of regenerated seedling on and around fallen wood on the west slope were more than that on the east slope. With the improvement of decomposition level,regenerated seedling per unit area firstly increased and then decreased,but the number of regenerated seedling on and around fallen wood was far more than that in woodland.
