It is important to predict how many individuals of a predator species can survive in a given area on the basis of prey sufficiency and to compare predictive estimates with actual numbers to understand whether or not k...It is important to predict how many individuals of a predator species can survive in a given area on the basis of prey sufficiency and to compare predictive estimates with actual numbers to understand whether or not key threats are related to prey availability.Rugged terrain and low detection probabilities do not allow for the use of traditional prey count techniques in mountain areas.We used presence–absence occupancy modeling and camera-trapping to estimate the abundance and densities of prey species and regression analysis to predict leopard(Panthera pardus)densities from estimated prey biomass in the mountains of the Nuvadi area,Meghri Ridge,southern Armenia.The prey densities were 12.94±2.18 individuals km–2 for the bezoar goat(Capra aegagrus),6.88±1.56 for the wild boar(Sus scrofa)and 0.44±0.20 for the roe deer(Capreolus capreolus).The detection probability of the prey was a strong function of the activity patterns,and was highest in diurnal bezoar goats(0.59±0.09).Based on robust regression,the estimated total ungulate prey biomass(720.37±142.72 kg km–2)can support a leopard density of 7.18±3.06 individuals 100 km–2.The actual leopard density is only 0.34 individuals 100 km–2(i.e.one subadult male recorded over the 296.9 km2),estimated from tracking and camera-trapping.The most plausible explanation for this discrepancy between predicted and actual leopard density is that poaching and disturbance caused by livestock breeding,plant gathering,deforestation and human-induced wild fires are affecting the leopard population in Armenia.展开更多
Fathers play an important role in adolescents’development,which is significant for their development and influences their mental health,including feeling of loneliness.However,the effects and mechanisms of father-lov...Fathers play an important role in adolescents’development,which is significant for their development and influences their mental health,including feeling of loneliness.However,the effects and mechanisms of father-love absence on individual loneliness are not clear.Based on the social functionalist theory and the social needs theory,this study examines the influence of individual fatherlove absence on loneliness and its underlying mechanisms.A questionnaire survey was administered to 319 junior high school students and 1,476 high school students.The results showed that adolescents with father-love absence had higher levels of loneliness,and that father-love absence affected loneliness levels through mediating pathways of individual gratitude,peer relationships,and gratitude to peer relationships.This study not only confirms the negative effects of father-love absence on adolescents’loneliness,but also explains the mediate roles of individual gratitude and peer relationships.It enriches the theoretical system related to family education and has important theoretical and practical implications for further interventions on adolescents’mental health from the perspective of fatherless parenting.展开更多
Over the past few years,China’s higher education institutions have experienced remarkable growth in online teaching.However,it remains uncertain whether and how the sense of presence perceived by students affects the...Over the past few years,China’s higher education institutions have experienced remarkable growth in online teaching.However,it remains uncertain whether and how the sense of presence perceived by students affects their online learning outcomes when teachers use online teaching media for communication.This sense specifically pertains to the extent to which students perceive themselves as“real persons”and establish connections with others.Therefore,this study constructs a conceptual model elucidating the impact of presence on students’online learning outcomes and empirically examines the mechanism through which three types of presence influence students’online learning.The test results of the structural equation modeling(SEM)indicate that:(a)teaching presence,social presence,and cognitive presence all exhibit significantly positive outcomes on students’online learning outcomes;(b)these three types of presence can also indirectly and positively influence students’online learning outcomes through the mediating effect of flow experience and learning satisfaction;and(c)flow experience and learning satisfaction play a sequential mediating role in the process by which presence impacts students’online learning outcomes.We hope that the relevant research findings may contribute to unveiling the“black box”of the impact of presence on students’online learning outcomes and offer valuable insights for college educators to overcome online teaching constraints and enhance online teaching quality.展开更多
Agrizim and bayleton,two commonly usedagricultural fungicides in India,wereinvestigated for their genotoxicpotentialities on cultured humanlymphocytes by studying chromosomalaberrations and sister chromatid exchangesi...Agrizim and bayleton,two commonly usedagricultural fungicides in India,wereinvestigated for their genotoxicpotentialities on cultured humanlymphocytes by studying chromosomalaberrations and sister chromatid exchangesin the presence and absence of展开更多
Enhancing the sense of presence of participants is an important issue in terms of security awareness for remote collaboration in extended reality.However,conventional methods are insufficient to be aware of remote sit...Enhancing the sense of presence of participants is an important issue in terms of security awareness for remote collaboration in extended reality.However,conventional methods are insufficient to be aware of remote situations and to search for and control remote workspaces.This study pro-poses a spatial multi-presence system that simultaneously provides multiple spaces while rapidly exploring these spaces as users perform collaborative work in an extended reality environment.The proposed system provides methods for arranging and manipulating remote and personal spaces by creating an annular screen that is invisible to the user.The user can freely arrange remote participants and their workspaces on the annular screen.Because users can simultaneously view various spaces arranged on the annular screen,they can perform collaborative work while simultaneously feeling the presence of multiple spaces and can be fully immersed in a specific space.In addition,the personal spaces where users work can also be arranged through the annular screen.According to the results of the performance evaluations,users participating in remote collaborative works can visualize the spaces of multiple users simultaneously and feel their presence,thereby increasing their understanding of the spaces.Moreover,the proposed system reduces the time to perform tasks and gain awareness of the emergency in remote workspaces.展开更多
Background:Congenital absence of pericardium(CAP),also known as pericardial agenesis,represents an uncommon cardiac abnormality and mostly incidental finding.It can be subdivided into complete and partial(left or righ...Background:Congenital absence of pericardium(CAP),also known as pericardial agenesis,represents an uncommon cardiac abnormality and mostly incidental finding.It can be subdivided into complete and partial(left or right-sided)forms.Because of its infrequency,just case reports and a few case series have been released so far.This paper represents the largest systematic review in the field.Nine features(age at diagnosis,type,gender,clinical presentation,electrocardiography,imaging(ultrasounds,CT/MRI),concomitant cardiac defects,and outcome)were analysed.Methods:The electronic database PubMed was investigated from its establishment up to July 15th,2023.Just case reports and case series were included.Animal studies,papers that were not in English,Spanish,and Italian,and those manuscripts not reporting at least seven of the nine analysed features.were ruled out.The analysed data were reported mostly in terms of percentage.Results:One hundred eighty studies were included encompassing 247 patients.More than half of reviewed CAP cases were in males(63.2%).The mean age at diagnosis was 31.8±19.3 years;a range of 32 weeks of gestation-81 years).23.5%of the patients did not report any symptoms.The most common clinical presentations were chest pain(35.2%)and dyspnoea(29.2%).The most commonly seen ECG changes were right axis deviation(28.7%)and right bundle branch block(23.9%).CAP was suspected or diagnosed by echocardiography in 20.1%of cases.The diagnosis was made by CT and/or MRI in 61.9%of cases.CAP was left-sided in 71.2%,complete in 23.1%,and right-sided in 5.7%.A concomitant congenital heart defect was found in 22.7%,especially in the form of atrial septal defect(6.5%)and patency of ductus arteriosus(2.8%).The pericardial repair was required in 12.9% of the incomplete forms of the disease.Never did the complete form require surgical correction.The outcome appeared favourable in the vast majority of cases,with just 18 deaths(7.3%).Discussion:The main limitation of this systematic review is that it is based just on case reports and case series,due to the lack of large studies on CAP.However,it represents the largest analysis in the field.Due to the rarity of CAP establishing an International Registry is recommended.展开更多
BACKGROUND Zollinger–Ellison syndrome(ZES)results from hypersecretion of gastrin from pancreatic or duodenal neuroendocrine tumors,commonly referred to as gastrinomas.The high levels of gastrin lead to a typical pres...BACKGROUND Zollinger–Ellison syndrome(ZES)results from hypersecretion of gastrin from pancreatic or duodenal neuroendocrine tumors,commonly referred to as gastrinomas.The high levels of gastrin lead to a typical presentation involving watery diarrhea and multiple ulcers in the duodenum.Here,we have presented the rare case of a patient with ZES and absence of hypergastrinemia as well as an atypical location of gastrinoma.CASE SUMMARY A 72-year-old woman presented with the typical clinical manifestations of ZES,including upper abdominal pain,significant watery diarrhea,and acidic liquid vomitus.Surprisingly,however,she did not have an increased level of serum gastrin.In addition,there was no evidence of gastrinoma or any other ulcerogenic tumor.Esophagogastroduodenoscopy was conducted to examine the upper digestive tract.Revised diagnoses were considered,and an individualized treatment plan was developed.The patient responded to antacid medication while experiencing intermittent,recurring bouts of ZES.18F-AlF-NOTAoctreotide positron emission tomography(18F-OC PET)/computed tomography(CT)helped locate the tumor.Postoperative pathology and immunohistochemistry results suggested that the tumor was a gastrinoma located at an unconventional site.CONCLUSION This present case study demonstrates the possibility of ZES-like manifestation in patients with absence of hypergastrinemia.18F-OC PET/CT is a relatively new imaging technique that can be applied for diagnosing even tiny gastrinomas that are atypical in terms of location.展开更多
With the rapid development of immersive multimedia technologies,360-degree video services have quickly gained popularity and how to ensure sufficient spatial presence of end users when viewing 360-degree videos become...With the rapid development of immersive multimedia technologies,360-degree video services have quickly gained popularity and how to ensure sufficient spatial presence of end users when viewing 360-degree videos becomes a new challenge.In this regard,accurately acquiring users’sense of spatial presence is of fundamental importance for video service providers to improve their service quality.Unfortunately,there is no efficient evaluation model so far for measuring the sense of spatial presence for 360-degree videos.In this paper,we first design an assessment framework to clarify the influencing factors of spatial presence.Related parameters of 360-degree videos and headmounted display devices are both considered in this framework.Well-designed subjective experiments are then conducted to investigate the impact of various influencing factors on the sense of presence.Based on the subjective ratings,we propose a spatial presence assessment model that can be easily deployed in 360-degree video applications.To the best of our knowledge,this is the first attempt in literature to establish a quantitative spatial presence assessment model by using technical parameters that are easily extracted.Experimental results demonstrate that the proposed model can reliably predict the sense of spatial presence.展开更多
The analysis of company data useful for economic decisions,if not interpreted in an overall view of the company situation,can lead to wrong conclusions.This is the case when a company has to choose between several sal...The analysis of company data useful for economic decisions,if not interpreted in an overall view of the company situation,can lead to wrong conclusions.This is the case when a company has to choose between several sales options for one or more products in the presence of a limiting factor.The continuation of the investigation often denies the initial analysis.Not everything is as it appears,therefore,at the beginning of the deepening of the data useful for economic decisions.As it is well known,the choices of profitability concerning the planning of the sale of company products take place,at least in the majority of cases,through the determination of the contribution margin,i.e.the profitability margin connected to the individual goods/services sold by the companies(selling price net of variable costs).The contribution margin can be determined with four objectives:(1)Determination of the yield of the single product,net of variable costs only.In this case,the margin defines unitary,from net product yield to unitary contribution margin.(2)Determination of the return on total sales of an individual product,net of variable costs.In this hypothesis,reference is made to the first level(or gross)contribution margin.(3)Determination of the ability of the individual product to contribute to the coverage of fixed costs common to the company.This margin is determined net of special product variable and fixed costs.This aggregate is defined as a Level II(or semi-gross)margin.(4)Determination of the useful value in the planning choices in case of presence of scarce productive factors.In this case,it must identify the so-called unitary margin for low factor.Here we will only deal with the problem of the use of the contribution margin in the presence of rare factors.To complete the analysis,below are some very brief considerations regarding,respectively,the unitary,level I,and level II contribution margin in order to better understand where the problem of the most convenient choice of income is located in the event of the presence of rare production factors,especially in an environment characterized by a plurality of sales options.展开更多
Progress is described regarding the development of a new electrotactile feedback glove designed for application to dexterous robot. The sensitivity of operator's finger against electrical stimulus pulse is conside...Progress is described regarding the development of a new electrotactile feedback glove designed for application to dexterous robot. The sensitivity of operator's finger against electrical stimulus pulse is considered. It is found that frequency, duty ratio, and voltage amplitude of electrical stimulus pulse determine the sensitivity of finger. The effects of materials, sizes, arrangements and shapes of electrodes on sensitivity of finger are analyzed. Finally, the tactile tele presence system is designed to experimentally confirm that the robot with electrotactile feedback glove can manipulate dexterous robotic multi fingered hand and identify and classify three sorts of objects.展开更多
BACKGROUND Researchers have investigated the diagnostic value of protein induced by vitamin K absence or antagonist II (PIVKA-II) and alpha-fetoprotein (AFP) in hepatitis B virus (HBV)-related hepatocellular carcinoma...BACKGROUND Researchers have investigated the diagnostic value of protein induced by vitamin K absence or antagonist II (PIVKA-II) and alpha-fetoprotein (AFP) in hepatitis B virus (HBV)-related hepatocellular carcinoma (HCC), and obtained abundant clinical diagnostic data. However, PIVKA-II and AFP have unsatisfactory specificity and sensitivity in the diagnosis of early-stage HBV-related HCC. Gamma-glutamyltransferase (γ-GT) and aspartate aminotransferase (AST) are common biomarkers for evaluating liver function, and we hypothesized that the γ-GT/AST ratio in combination with PIVKA-II and AFP would improve the diagnosis of early-stage HBV-related HCC. AIM To evaluate the diagnostic value of γ-GT/AST ratio alone or in combination with PIVKA-II and AFP in HBV-related HCC. METHODS Serum levels of γ-GT, AST, PIVKA-II, and AFP were detected and analysed in 176 patients with HBV-related HCC and in 359 patients with chronic hepatitis B. According to tumour size and serum level of HBV DNA, HBV-related HCC patients were divided into the following categories: Early-stage HCC patients, HCC patients, HBV DNA positive (HBV DNA+) HCC patients, and HBV DNA negative (HBV DNA-) HCC patients. Receiver-operating characteristic (ROC) curves were used to analyse and compare the diagnostic value of the single and combined detection of various biomarkers in different types of HBV-related HCC. RESULTS Tumour size was positively correlated with serum levels of PIVKA-II and AFP in HCC patients (r = 0.529, aP < 0.001 and r = 0.270, bP < 0.001, respectively), but there was no correlation between tumour size and the γ-GT/AST ratio (r = 0.073, P = 0.336). The areas under the receiver-operating characteristic curves (AUROCs) of the γ-GT/AST ratio in early-stage HCC patients, HBV DNA+ HCC patients and HBV DNA- HCC patients were not significantly different from that in the total HCC patients (0.754, 0.802, and 0.705 vs 0.779, respectively;P > 0.05). When PIVKA-II was combined with the γ-GT/AST ratio in the diagnosis of earlystage HCC, HCC, and HBV DNA+ HCC, the AUROCs of PIVKA-II increased, with values of 0.857 vs 0.835, 0.925 vs 0.913, and 0.958 vs 0.954, respectively. When AFP was combined with the γ-GT/AST ratio in the diagnosis of early-stage HCC, HCC, HBV DNA+ HCC, and HBV DNA- HCC, the AUROCs of AFP increased, with values of 0.757 vs 0.621, 0.837 vs 0.744, 0.868 vs 0.757, and 0.840 vs 0.828, respectively. CONCLUSION The γ-GT/AST ratio may be better than PIVKA-II and AFP in the diagnosis of early-stage HBV-related HCC, and its combination with PIVKA-II and AFP can improve the diagnostic value for HBV-related HCC.展开更多
文摘It is important to predict how many individuals of a predator species can survive in a given area on the basis of prey sufficiency and to compare predictive estimates with actual numbers to understand whether or not key threats are related to prey availability.Rugged terrain and low detection probabilities do not allow for the use of traditional prey count techniques in mountain areas.We used presence–absence occupancy modeling and camera-trapping to estimate the abundance and densities of prey species and regression analysis to predict leopard(Panthera pardus)densities from estimated prey biomass in the mountains of the Nuvadi area,Meghri Ridge,southern Armenia.The prey densities were 12.94±2.18 individuals km–2 for the bezoar goat(Capra aegagrus),6.88±1.56 for the wild boar(Sus scrofa)and 0.44±0.20 for the roe deer(Capreolus capreolus).The detection probability of the prey was a strong function of the activity patterns,and was highest in diurnal bezoar goats(0.59±0.09).Based on robust regression,the estimated total ungulate prey biomass(720.37±142.72 kg km–2)can support a leopard density of 7.18±3.06 individuals 100 km–2.The actual leopard density is only 0.34 individuals 100 km–2(i.e.one subadult male recorded over the 296.9 km2),estimated from tracking and camera-trapping.The most plausible explanation for this discrepancy between predicted and actual leopard density is that poaching and disturbance caused by livestock breeding,plant gathering,deforestation and human-induced wild fires are affecting the leopard population in Armenia.
基金the General Program of the National Socail Science Fund of China(23BSH144).
文摘Fathers play an important role in adolescents’development,which is significant for their development and influences their mental health,including feeling of loneliness.However,the effects and mechanisms of father-love absence on individual loneliness are not clear.Based on the social functionalist theory and the social needs theory,this study examines the influence of individual fatherlove absence on loneliness and its underlying mechanisms.A questionnaire survey was administered to 319 junior high school students and 1,476 high school students.The results showed that adolescents with father-love absence had higher levels of loneliness,and that father-love absence affected loneliness levels through mediating pathways of individual gratitude,peer relationships,and gratitude to peer relationships.This study not only confirms the negative effects of father-love absence on adolescents’loneliness,but also explains the mediate roles of individual gratitude and peer relationships.It enriches the theoretical system related to family education and has important theoretical and practical implications for further interventions on adolescents’mental health from the perspective of fatherless parenting.
基金the project“Research on the Evaluation Mechanism of College Ideological and Political Education:A Perspective on Teacher-Student Development,”funded by Zhejiang Provincial College Ideological and Political Education Research Project.
文摘Over the past few years,China’s higher education institutions have experienced remarkable growth in online teaching.However,it remains uncertain whether and how the sense of presence perceived by students affects their online learning outcomes when teachers use online teaching media for communication.This sense specifically pertains to the extent to which students perceive themselves as“real persons”and establish connections with others.Therefore,this study constructs a conceptual model elucidating the impact of presence on students’online learning outcomes and empirically examines the mechanism through which three types of presence influence students’online learning.The test results of the structural equation modeling(SEM)indicate that:(a)teaching presence,social presence,and cognitive presence all exhibit significantly positive outcomes on students’online learning outcomes;(b)these three types of presence can also indirectly and positively influence students’online learning outcomes through the mediating effect of flow experience and learning satisfaction;and(c)flow experience and learning satisfaction play a sequential mediating role in the process by which presence impacts students’online learning outcomes.We hope that the relevant research findings may contribute to unveiling the“black box”of the impact of presence on students’online learning outcomes and offer valuable insights for college educators to overcome online teaching constraints and enhance online teaching quality.
文摘Agrizim and bayleton,two commonly usedagricultural fungicides in India,wereinvestigated for their genotoxicpotentialities on cultured humanlymphocytes by studying chromosomalaberrations and sister chromatid exchangesin the presence and absence of
基金supported by“Regional Innovation Strategy(RIS)”through the National Research Foundation of Korea(NRF)funded by the Ministry of Education(MOE)(2021RIS-004).
文摘Enhancing the sense of presence of participants is an important issue in terms of security awareness for remote collaboration in extended reality.However,conventional methods are insufficient to be aware of remote situations and to search for and control remote workspaces.This study pro-poses a spatial multi-presence system that simultaneously provides multiple spaces while rapidly exploring these spaces as users perform collaborative work in an extended reality environment.The proposed system provides methods for arranging and manipulating remote and personal spaces by creating an annular screen that is invisible to the user.The user can freely arrange remote participants and their workspaces on the annular screen.Because users can simultaneously view various spaces arranged on the annular screen,they can perform collaborative work while simultaneously feeling the presence of multiple spaces and can be fully immersed in a specific space.In addition,the personal spaces where users work can also be arranged through the annular screen.According to the results of the performance evaluations,users participating in remote collaborative works can visualize the spaces of multiple users simultaneously and feel their presence,thereby increasing their understanding of the spaces.Moreover,the proposed system reduces the time to perform tasks and gain awareness of the emergency in remote workspaces.
文摘Background:Congenital absence of pericardium(CAP),also known as pericardial agenesis,represents an uncommon cardiac abnormality and mostly incidental finding.It can be subdivided into complete and partial(left or right-sided)forms.Because of its infrequency,just case reports and a few case series have been released so far.This paper represents the largest systematic review in the field.Nine features(age at diagnosis,type,gender,clinical presentation,electrocardiography,imaging(ultrasounds,CT/MRI),concomitant cardiac defects,and outcome)were analysed.Methods:The electronic database PubMed was investigated from its establishment up to July 15th,2023.Just case reports and case series were included.Animal studies,papers that were not in English,Spanish,and Italian,and those manuscripts not reporting at least seven of the nine analysed features.were ruled out.The analysed data were reported mostly in terms of percentage.Results:One hundred eighty studies were included encompassing 247 patients.More than half of reviewed CAP cases were in males(63.2%).The mean age at diagnosis was 31.8±19.3 years;a range of 32 weeks of gestation-81 years).23.5%of the patients did not report any symptoms.The most common clinical presentations were chest pain(35.2%)and dyspnoea(29.2%).The most commonly seen ECG changes were right axis deviation(28.7%)and right bundle branch block(23.9%).CAP was suspected or diagnosed by echocardiography in 20.1%of cases.The diagnosis was made by CT and/or MRI in 61.9%of cases.CAP was left-sided in 71.2%,complete in 23.1%,and right-sided in 5.7%.A concomitant congenital heart defect was found in 22.7%,especially in the form of atrial septal defect(6.5%)and patency of ductus arteriosus(2.8%).The pericardial repair was required in 12.9% of the incomplete forms of the disease.Never did the complete form require surgical correction.The outcome appeared favourable in the vast majority of cases,with just 18 deaths(7.3%).Discussion:The main limitation of this systematic review is that it is based just on case reports and case series,due to the lack of large studies on CAP.However,it represents the largest analysis in the field.Due to the rarity of CAP establishing an International Registry is recommended.
基金National Natural Science Foundation of China,No.82100612Zhejiang Medical Health Science and Technology Plan Project,No.2021KY1116。
文摘BACKGROUND Zollinger–Ellison syndrome(ZES)results from hypersecretion of gastrin from pancreatic or duodenal neuroendocrine tumors,commonly referred to as gastrinomas.The high levels of gastrin lead to a typical presentation involving watery diarrhea and multiple ulcers in the duodenum.Here,we have presented the rare case of a patient with ZES and absence of hypergastrinemia as well as an atypical location of gastrinoma.CASE SUMMARY A 72-year-old woman presented with the typical clinical manifestations of ZES,including upper abdominal pain,significant watery diarrhea,and acidic liquid vomitus.Surprisingly,however,she did not have an increased level of serum gastrin.In addition,there was no evidence of gastrinoma or any other ulcerogenic tumor.Esophagogastroduodenoscopy was conducted to examine the upper digestive tract.Revised diagnoses were considered,and an individualized treatment plan was developed.The patient responded to antacid medication while experiencing intermittent,recurring bouts of ZES.18F-AlF-NOTAoctreotide positron emission tomography(18F-OC PET)/computed tomography(CT)helped locate the tumor.Postoperative pathology and immunohistochemistry results suggested that the tumor was a gastrinoma located at an unconventional site.CONCLUSION This present case study demonstrates the possibility of ZES-like manifestation in patients with absence of hypergastrinemia.18F-OC PET/CT is a relatively new imaging technique that can be applied for diagnosing even tiny gastrinomas that are atypical in terms of location.
基金supported in part by ZTE Industry⁃University⁃Institute Coop⁃eration Funds.
文摘With the rapid development of immersive multimedia technologies,360-degree video services have quickly gained popularity and how to ensure sufficient spatial presence of end users when viewing 360-degree videos becomes a new challenge.In this regard,accurately acquiring users’sense of spatial presence is of fundamental importance for video service providers to improve their service quality.Unfortunately,there is no efficient evaluation model so far for measuring the sense of spatial presence for 360-degree videos.In this paper,we first design an assessment framework to clarify the influencing factors of spatial presence.Related parameters of 360-degree videos and headmounted display devices are both considered in this framework.Well-designed subjective experiments are then conducted to investigate the impact of various influencing factors on the sense of presence.Based on the subjective ratings,we propose a spatial presence assessment model that can be easily deployed in 360-degree video applications.To the best of our knowledge,this is the first attempt in literature to establish a quantitative spatial presence assessment model by using technical parameters that are easily extracted.Experimental results demonstrate that the proposed model can reliably predict the sense of spatial presence.
文摘The analysis of company data useful for economic decisions,if not interpreted in an overall view of the company situation,can lead to wrong conclusions.This is the case when a company has to choose between several sales options for one or more products in the presence of a limiting factor.The continuation of the investigation often denies the initial analysis.Not everything is as it appears,therefore,at the beginning of the deepening of the data useful for economic decisions.As it is well known,the choices of profitability concerning the planning of the sale of company products take place,at least in the majority of cases,through the determination of the contribution margin,i.e.the profitability margin connected to the individual goods/services sold by the companies(selling price net of variable costs).The contribution margin can be determined with four objectives:(1)Determination of the yield of the single product,net of variable costs only.In this case,the margin defines unitary,from net product yield to unitary contribution margin.(2)Determination of the return on total sales of an individual product,net of variable costs.In this hypothesis,reference is made to the first level(or gross)contribution margin.(3)Determination of the ability of the individual product to contribute to the coverage of fixed costs common to the company.This margin is determined net of special product variable and fixed costs.This aggregate is defined as a Level II(or semi-gross)margin.(4)Determination of the useful value in the planning choices in case of presence of scarce productive factors.In this case,it must identify the so-called unitary margin for low factor.Here we will only deal with the problem of the use of the contribution margin in the presence of rare factors.To complete the analysis,below are some very brief considerations regarding,respectively,the unitary,level I,and level II contribution margin in order to better understand where the problem of the most convenient choice of income is located in the event of the presence of rare production factors,especially in an environment characterized by a plurality of sales options.
文摘Progress is described regarding the development of a new electrotactile feedback glove designed for application to dexterous robot. The sensitivity of operator's finger against electrical stimulus pulse is considered. It is found that frequency, duty ratio, and voltage amplitude of electrical stimulus pulse determine the sensitivity of finger. The effects of materials, sizes, arrangements and shapes of electrodes on sensitivity of finger are analyzed. Finally, the tactile tele presence system is designed to experimentally confirm that the robot with electrotactile feedback glove can manipulate dexterous robotic multi fingered hand and identify and classify three sorts of objects.
文摘BACKGROUND Researchers have investigated the diagnostic value of protein induced by vitamin K absence or antagonist II (PIVKA-II) and alpha-fetoprotein (AFP) in hepatitis B virus (HBV)-related hepatocellular carcinoma (HCC), and obtained abundant clinical diagnostic data. However, PIVKA-II and AFP have unsatisfactory specificity and sensitivity in the diagnosis of early-stage HBV-related HCC. Gamma-glutamyltransferase (γ-GT) and aspartate aminotransferase (AST) are common biomarkers for evaluating liver function, and we hypothesized that the γ-GT/AST ratio in combination with PIVKA-II and AFP would improve the diagnosis of early-stage HBV-related HCC. AIM To evaluate the diagnostic value of γ-GT/AST ratio alone or in combination with PIVKA-II and AFP in HBV-related HCC. METHODS Serum levels of γ-GT, AST, PIVKA-II, and AFP were detected and analysed in 176 patients with HBV-related HCC and in 359 patients with chronic hepatitis B. According to tumour size and serum level of HBV DNA, HBV-related HCC patients were divided into the following categories: Early-stage HCC patients, HCC patients, HBV DNA positive (HBV DNA+) HCC patients, and HBV DNA negative (HBV DNA-) HCC patients. Receiver-operating characteristic (ROC) curves were used to analyse and compare the diagnostic value of the single and combined detection of various biomarkers in different types of HBV-related HCC. RESULTS Tumour size was positively correlated with serum levels of PIVKA-II and AFP in HCC patients (r = 0.529, aP < 0.001 and r = 0.270, bP < 0.001, respectively), but there was no correlation between tumour size and the γ-GT/AST ratio (r = 0.073, P = 0.336). The areas under the receiver-operating characteristic curves (AUROCs) of the γ-GT/AST ratio in early-stage HCC patients, HBV DNA+ HCC patients and HBV DNA- HCC patients were not significantly different from that in the total HCC patients (0.754, 0.802, and 0.705 vs 0.779, respectively;P > 0.05). When PIVKA-II was combined with the γ-GT/AST ratio in the diagnosis of earlystage HCC, HCC, and HBV DNA+ HCC, the AUROCs of PIVKA-II increased, with values of 0.857 vs 0.835, 0.925 vs 0.913, and 0.958 vs 0.954, respectively. When AFP was combined with the γ-GT/AST ratio in the diagnosis of early-stage HCC, HCC, HBV DNA+ HCC, and HBV DNA- HCC, the AUROCs of AFP increased, with values of 0.757 vs 0.621, 0.837 vs 0.744, 0.868 vs 0.757, and 0.840 vs 0.828, respectively. CONCLUSION The γ-GT/AST ratio may be better than PIVKA-II and AFP in the diagnosis of early-stage HBV-related HCC, and its combination with PIVKA-II and AFP can improve the diagnostic value for HBV-related HCC.