Background and Objective The development of modern palliative care in China began in the 1980s and is currently in an accelerating phase.However,inconsistencies in terminology and concepts have hindered policy-making,...Background and Objective The development of modern palliative care in China began in the 1980s and is currently in an accelerating phase.However,inconsistencies in terminology and concepts have hindered policy-making,clinical practice,and academic research.The Terminology of Clinical Medicine(2023 edition)has determined huan-he-yi-liao(缓和医疗)and an-ning-liao-hu(安宁疗护)as the formal terms of"palliative care"and"hospice care",respectively.To align with these terms,this study aims to establish expert consensus definitions tailored to the Chinese context.Methods We systematically retrieved and collected domestic and international literature and policy documents related to the definition of palliative care,then deconstructed and analyzed the relevant conceptual elements of these definitions.Core expert panel built the initial recommended definition upon the conceptual elements and consensus definition of palliative care by the International Association for Hospice and Palliative Care(IAHPC)through two rounds of online discussions.After nomination and selection,61 professionals in the field of palliative care in China were invited to participate in the consensus expert group.Two rounds of Delphi consultation were conducted among the consensus experts,who were asked to score their agreement using Likert scale to the items in the initial recommended definition and the definition statements of palliative care and hospice care.Agreement rate of over 80%was considered as reaching consensus for each items.The core expert panel revised the items and the statements of recommended definitions based on the results from Delphi surveys.The final recommended definitions were formulated after feedback from patient and public involvement(PPI)group members.Results The response rates for the first and second round of Delphi surveys were 83.6%and 100.0%,respectively.The agreement rates of the items and statements of the recommended definitions exceeded 90%.Accordingly,the definitions based on Chinese expert consensus are recommended.Palliative care is an active holistic approach aimed at patients of all ages suffering from life-threatening illness and their families and caregivers.It seeks to improve their quality of life by preventing,assessing,and relieving physical,psychological,social,and spiritual suffering.Hospice care is an integral part of palliative care,focusing on holistic care for patients at the end of life and their families and caregivers.Its goal is to help patients to maintain dignity and achieve a good death by alleviating physical,psychological,social,and spiritual distress without intentionally hastening or postponing death,meanwhile improve the quality of life for families and caregivers.Conclusions This study has established the Chinese expert consensus definitions of palliative care and hospice care in China,as well as the relationship between the two.The definitions highlight the holistic nature of palliative care,providing a foundation for discipline development,clinical practice,and public communication.展开更多
Accurate drought assessment demands thoughtful consideration of drought definition first of all.Drought is commonly defined as a prolonged period of below-average precipitation leading to water shortages that impact e...Accurate drought assessment demands thoughtful consideration of drought definition first of all.Drought is commonly defined as a prolonged period of below-average precipitation leading to water shortages that impact ecosystems,agriculture,and human societies.However,meteorologists,hydrologists,and agronomists often use different criteria to define drought,depending on their specific focus areas.For example,hydrologists define drought according to water deficits in some components of the hydrological cycle(such as precipitation,soil moisture,river flow,and groundwater)or its impacts on the level of services provided to public water supply,irrigation,or hydropower demands(Tate and Gustard,2000).Differences in drought definitions may result in great uncertainties in drought assessment(Satoh et al.,2021).We cannot expect the existence of any workable generalized objective definition of drought(Lloyd-Hughes,2014).展开更多
BACKGROUND Fever of unknown origin(FUO)remains a diagnostic challenge and was originally defined in 1961.Its classic criteria include fever≥38.3°C(≥101°F)on multiple occasions,fever lasting three weeks or ...BACKGROUND Fever of unknown origin(FUO)remains a diagnostic challenge and was originally defined in 1961.Its classic criteria include fever≥38.3°C(≥101°F)on multiple occasions,fever lasting three weeks or longer,and a diagnosis after one week of inpatient evaluation.However,these criteria may not fully encompass the varied clinical presentations seen in resource-limited settings such as India.The adaptation of FUO definitions to local healthcare contexts is crucial for enhancing diagnostic accuracy and optimizing patient outcomes.AIM To investigate the applicability of revised FUO criteria in a tertiary care setting in India.METHODS This longitudinal-exploratory study at All India Institute of Medical Sciences Rishikesh(January 2018–December 2022)analyzed 228 adult patients with fever≥99.1°F lasting over three days.Patients diagnosed within three days of admission were excluded.Data were collected retrospectively and prospectively using predefined FUO definitions based on durations of nondiagnosis(3-21 days,>21 days),temperature ranges(99.1°F-100.9°F,≥101°F),and hospitalization durations(3-7 days,>7 days).Descriptive statistics and comparative tests(Fisher's exact test,χ2 test)evaluated outcomes across definitions.RESULTS Among the proposed FUO definitions,Definition B(fever lasting 3-21 days,temperatures between 99.1°F-100.9°F,hospitalization>7 days)predominated(40.8%),while only 2.2%met the classical criteria.Notably,36.5%of Definition B patients remained undiagnosed after 7-10 days,despite 94%undergoing diagnostic workups within 21 days.Infection emerged as the leading etiology across definitions,without significant variation in outcomes or mortality during hospitalization(χ2=27.937,P=0.142).CONCLUSION Adapting FUO criteria to local contexts improves diagnostic accuracy and treatment.Definition B(40.8%prevalence)showed practical utility,with higher mortality in patients discharged on empirical'Anti-tuberculosis therapy'.展开更多
The Global Stratotype Section and Point(GSSP)of the base-Wuchiapingian Stage was formally ratified at the Penglaitan section in South China in 2005.However,the riverside GSSP section at Penglaitan and its auxiliary se...The Global Stratotype Section and Point(GSSP)of the base-Wuchiapingian Stage was formally ratified at the Penglaitan section in South China in 2005.However,the riverside GSSP section at Penglaitan and its auxiliary section at Tieqiao have been permanently flooded since 2020.We herein designate an excavated section at Penglaitan as the new GSSP and the Fengshan section as a new Standard Auxiliary Boundary Stratotype(SABS).In addition,we revised the original definition based on a detailed restudy of the conodont succession from the two sections.We define the GSSP of the base-Wuchiapingian by the First Appearance Datum(FAD)of Clarkina postbitteri within the lineage Jinogondolella granti→Clarkina postbitteri→C.dukouensis.It represents a major evolutionary turnover in conodonts from Jinogondolella to Clarkina and marks the end-Guadalupian extinction event.The U-Pb date of 259.51±0.21 Ma from the uppermost part of the Emeishan basalt is adopted for the GLB age.δ13Ccarb chemostratigraphy at the SABS exhibits several excursions between 3‰and 5‰across the GLB interval.Carbonate 87Sr/86Sr ratio is 0.707244 at the GLB.Remarkably,the SABS contains six normal and six reverse geomagnetic polarity zones in the uppermost Capitanian and three in the lowest Wuchiapingian.展开更多
This paper puts forword 11 cartographic generalization operator models and introduces their mathematical definitions,and thus a precise mathematical form and quantitative description has been given to these formerly l...This paper puts forword 11 cartographic generalization operator models and introduces their mathematical definitions,and thus a precise mathematical form and quantitative description has been given to these formerly limited qualitative concepts.The meaning of mathematical definition of operators for cartographic generalization and the application prospect in computer_aided cartography (CAC) is stated.ract The Jurassic strata in Jingyan of Sichuan containing the Mamenchinsaurus fauna are dealt with and divided in this paper. The Mamenchisaurus fossils contained there are compared in morphological features and stratigraphically with other types of the genus on by one. The comprehensive analysis show that the Mamenchisaurus fauna of Jingyan appeared in the early Late Jurassic and is primitive in morphology. The results of the morphological identification and stratigraphical study agree with each other. Their evolutionary processes in different apoches of the Late Jurassic also made clear. Key words Jingyan, Sichuan, Mamenchisaurus Fauna, stratigraphy, evolution展开更多
BACKGROUND Sessile serrated adenomas(SSAs)are important premalignant lesions that are difficult to detect during colonoscopy due to poor definition,concealment by mucous caps,and flat appearance.High definition(HD)col...BACKGROUND Sessile serrated adenomas(SSAs)are important premalignant lesions that are difficult to detect during colonoscopy due to poor definition,concealment by mucous caps,and flat appearance.High definition(HD)colonoscopy may uniquely aid in the detection of these inconspicuous lesions compared to standard definition(SD)colonoscopes.In the absence of existing clinical guidelines to obligate the use of HD colonoscopy for colorectal cancer screening in average-risk patients,demonstrating the benefit of HD colonoscopy on SSA detection rate(SSADR)may help strengthen the evidence to recommend its use in all settings.AIM To evaluate the benefit of HD colonoscopy compared to SD colonoscopy on SSADR in average-risk patients undergoing screening colonoscopy.METHODS Data from screening colonoscopies for patients aged 50-76 years two years before and two years after the transition from SD colonoscopy to HD colonoscopy at our large,academic teaching center were collected.Patients with symptoms of colorectal disease,positive occult blood test,history of colon polyps,cancer,polyposis syndrome,inflammatory bowel disease or family history of colon cancer or polyps were excluded.Patients whose endoscopists did not perform colonoscopies both before and after scope definition change were also excluded.Differences in individual endoscopist SSADR,average SSADR,and overall SSADR with SD colonoscopy vs HD colonoscopy were also evaluated for significance.RESULTS A total of 3657 colonoscopies met eligibility criteria with 2012 colonoscopies from the SD colonoscopy period and 1645 colonoscopies from the HD colonoscopy period from a pool of 11 endoscopists.Statistically significant improvements of 2.30%in mean SSADR and 2.53%in overall SSADR were noted with HD colonoscopy(P=0.00028 and P=0.00849,respectively).On the individual level,three endoscopists experienced statistically significant benefit with HD colonoscopy(+5.74%,P=0.0056;+4.50%,P=0.0278;+4.84%,P=0.03486).CONCLUSION Our study suggests that HD colonoscopy statistically significantly improves sessile serrated adenoma detection rate in the screening of average risk patients during screening colonoscopy.By improving the detection and removal of these lesions,adoption of HD colonoscopy may reduce the significant premalignant burden of sessile serrated adenomas.展开更多
It is known that there exist obivious differences between the two most commonly used definitions of fractional derivatives-Riemann-Liouville （R-L） definition and Caputo definition. The multiple definitions of fracti...It is known that there exist obivious differences between the two most commonly used definitions of fractional derivatives-Riemann-Liouville （R-L） definition and Caputo definition. The multiple definitions of fractional derivatives in fractional calculus have hindered the application of fractional calculus in rheology. In this paper, we clarify that the R-L definition and Caputo definition are both rheologically imperfect with the help of mechanical analogues of the fractional element model （Scott-Blair model）. We also clarify that to make them perfect rheologically, the lower terminals of both definitions should be put to ∞. We further prove that the R-L definition with lower terminal a →∞ and the Caputo definition with lower terminal a →∞ are equivalent in the differentiation of functions that are smooth enough and functions that have finite number of singular points. Thus we can define the fractional derivatives in rheology as the R-L derivatives with lower terminal a →∞ （or, equivalently, the Caputo derivatives with lower terminal a →∞） not only for steady-state processes, but also for transient processes. Based on the above definition, the problems of composition rules of fractional operators and the initial conditions for fractional differential equations are discussed, respectively. As an example we study a fractional oscillator with Scott-Blair model and give an exact solution of this equation under given initial conditions.展开更多
The adaptability of features definition to applications is an essential condition for implementing feature based design. This paper makes attempt to present a hierarchical definition structure of features. The propos...The adaptability of features definition to applications is an essential condition for implementing feature based design. This paper makes attempt to present a hierarchical definition structure of features. The proposed scheme divides feature definition into application level, form level and geometric level, and provides links between different levels with feature semantics interpretation and enhanced geometric face adjacent graph. respectively. The results not only enable feature definition to abate from the specific dependence and become more extensive, but also provide a theoretical foundation for establishing the concurrent feature based design process model.展开更多
Benefiting from advances in feature technology for design and manufacture can not be expected before a formal methodology is established. This paper makes attempt to establish a definition formalism of machining featu...Benefiting from advances in feature technology for design and manufacture can not be expected before a formal methodology is established. This paper makes attempt to establish a definition formalism of machining features in design for manufacturability from two aspects: formal definition and manufacturability analysis. Some definitions for machining feature based upon the selection and sequencing of material removal operations for component in accordance with the design geometry are presented and a framework of feature based design for manufacturability is outlined correspondingly. The proposed scheme contributes to several aspects of feature based CAD/CAM integration, especially to encourage potentially a more generic approach to the automation of design.展开更多
During the last two decades fractional calculus has been increasingly applied to physics, especially to rheology.It is well known that there are obivious differences between Riemann-Liouville (R-L) definition and Capu...During the last two decades fractional calculus has been increasingly applied to physics, especially to rheology.It is well known that there are obivious differences between Riemann-Liouville (R-L) definition and Caputo definition,which are the two most commonly used definitions of fractional derivatives.The multiple definitions of fractional derivatives have hindered the application of fractional calculus in rheology.In this paper,we clarify that the R-L definition and Caputo definition are both Theologically unreasonable with the help of the mechanical analogues of the fractional element model.We also find that to make them more reasonable Theologically,the lower terminals of both definitions should be put to—∞.We further prove that the R-L definition with lower terminal—∞and the Caputo definition with lower terminal—∞are equivalent in the differentiation of functions that are smooth enough and functions that have finite number of singular points.Thus we can define the fractional derivatives in rheology as the R-L derivatives with lower terminal—∞(or,equivalently,the Caputo derivatives with lower terminal—∞) not only for steady-state processes,but also for transient processes.展开更多
Glacial lakes are not only the important refresh water resources in alpine region, but also act as a trigger of many glacial hazards such as glacial lake outburst flood （GLOF） and debris flow. Therefore, glacial lak...Glacial lakes are not only the important refresh water resources in alpine region, but also act as a trigger of many glacial hazards such as glacial lake outburst flood （GLOF） and debris flow. Therefore, glacial lakes play an important role on the cryosphere, climate change and alpine hazards. In this paper, the issues of glacial lake were systematically discussed, then from the view of glacial lake inventory and glacial lake hazards study, the glacial lake was defined as natural water mainly supplied by modern glacial meltwater or formed in glacier moraine＇s depression. Furthermore, a complete classification system of glacial lake was proposed based on its formation mechanism, topographic feature and geographical position. Glacial lakes were classified as 6 classes and 8 subclasses, i.e., glacial erosion lake （including cirque lake, gla- cial valley lake and other glacial erosion lake）, moraine-dammed lake （including end mo- raine-dammed lake, lateral moraine-dammed lake and moraine thaw lake）, ice-blocked lake （including advancing glacier-blocked lake and other glacier-blocked lake）, supraglacial lake, subglacial lake and other glacial lake. Meanwhile, some corresponding features exhibiting on remote sensing image and quantitative indices for identifying different glacial lake types were proposed in order to build a universal and operational classification system of glacial lake.展开更多
BACKGROUND:A number of definitions have been used for delayed gastric emptying(DGE) after pancreatoduodenectomy and the reported rates varied widely.The International Study Group of Pancreatic Surgery(ISGPS) definitio...BACKGROUND:A number of definitions have been used for delayed gastric emptying(DGE) after pancreatoduodenectomy and the reported rates varied widely.The International Study Group of Pancreatic Surgery(ISGPS) definition is the current standard but it is not used universally.In this comprehensive review,we aimed to determine the acceptance rate of ISGPS definition of DGE,the incidence of DGE after pancreatoduodenectomy and the effect of various technical modifications on its incidence.DATA SOURCE:We searched PubM ed for studies regarding DGE after pancreatoduodenectomy that were published from 1 January 1980 to 1 July 2015 and extracted data on DGE definition,DGE rates and comparison of DGE rates among different technical modifications from all of the relevant articles.RESULTS:Out of 435 search results,178 were selected for data extraction.The ISGPS definition was used in 80% of the studies published since 2010 and the average rates of DGE and clinically relevant DGE were 27.7%(range:0-100%;median:18.7%) and 14.3%(range:1.8%-58.2%;median:13.6%),respectively.Pylorus preservation or retrocolic reconstruction were not associated with increased DGE rates.Although pyloric dilatation,Braun’s entero-enterostomy and Billroth Ⅱ reconstruction were associated with significantly lower DGE rates,pyloric ring resection appears to be most promising with favorable results in 7 out of 10 studies.CONCLUSIONS:ISGPS definition of DGE has been used in majority of studies published after 2010.Clinically relevant DGE rates remain high at 14.3% despite a number of proposed surgical modifications.Pyloric ring resection seems to offer the most promising solution to reduce the occurrence of DGE.展开更多
BACKGROUND Despite the emerging knowledge about colorectal anastomotic leakage(CAL)through the increasing number of clinical and experimental studies, there is no generally accepted definition of CAL. Because of the w...BACKGROUND Despite the emerging knowledge about colorectal anastomotic leakage(CAL)through the increasing number of clinical and experimental studies, there is no generally accepted definition of CAL. Because of the wide variety of definitions used in literature, comparison of study outcomes and quality of care is complicated.AIM To reach consensus on the definition of CAL using a modified Delphi method.METHODS The RAND/UCLA appropriateness method was used. The expert panel consisted of international colorectal surgeons and researchers who had published three or more articles about CAL. The consensus process consisted of two online distributed questionnaires and a third round with a recommendation. In the questionnaires participants were asked to rate the appropriateness of statements using a 1-9 Likert scale. Consensus was defined as a panel median between 1-3 or 7-9 without disagreement. In the final round a recommendation was formed regarding the definition of CAL and the expert panel was asked if they agreed or disagreed.RESULTSTwenty-three authors participated in the first round and twenty-one finished the second round. After two rounds consensus was reached on 37 items(80%) in nine different categories. The International Study Group of Rectal Cancer definition is the most frequently advised general definition by our panel. Consensus was reached regarding the clinical symptoms of CAL, which serum markers contributes to the suspicion of CAL, which radiological and perioperative findings should be considered as CAL, which grading system is appropriate and if there should be a range of postoperative days in the definition. Eventually, 19 experts completed all three rounds of which 16(84%) agreed with our final recommendations for the definition of CAL.CONCLUSION A consensus-based recommendation for the definition of CAL was formed using our modified Delphi method that can be widely incorporated in the field.展开更多
Car routing solutions are omnipresent and solutions for pedestrians also exist.Furthermore,public or commercial buildings are getting bigger and the complexity of their internal structure has increased.Consequently,th...Car routing solutions are omnipresent and solutions for pedestrians also exist.Furthermore,public or commercial buildings are getting bigger and the complexity of their internal structure has increased.Consequently,the need for indoor routing solutions has emerged.Some prototypes are available,but they still lack semantically-enriched modelling (e.g.,access constraints,labels,etc.) and are not suitable for providing user-adaptive length-optimal routing in complex buildings.Previous approaches consider simple rooms,concave rooms,and corridors,but important characteristics such as distinct areas in huge rooms and solid obstacles inside rooms are not considered at all,although such details can increase navigation accuracy.By formally defining a weighted indoor routing graph,it is possible to create a detailed and user-adaptive model for route computation.The defined graph also contains semantic information such as room labels,door accessibility constraints,etc.Furthermore,one-way paths inside buildings are considered,as well as three-dimensional building parts,e.g.,elevators or stairways.A hierarchical structure is also possible with the presented graph model.展开更多
文摘Background and Objective The development of modern palliative care in China began in the 1980s and is currently in an accelerating phase.However,inconsistencies in terminology and concepts have hindered policy-making,clinical practice,and academic research.The Terminology of Clinical Medicine(2023 edition)has determined huan-he-yi-liao(缓和医疗)and an-ning-liao-hu(安宁疗护)as the formal terms of"palliative care"and"hospice care",respectively.To align with these terms,this study aims to establish expert consensus definitions tailored to the Chinese context.Methods We systematically retrieved and collected domestic and international literature and policy documents related to the definition of palliative care,then deconstructed and analyzed the relevant conceptual elements of these definitions.Core expert panel built the initial recommended definition upon the conceptual elements and consensus definition of palliative care by the International Association for Hospice and Palliative Care(IAHPC)through two rounds of online discussions.After nomination and selection,61 professionals in the field of palliative care in China were invited to participate in the consensus expert group.Two rounds of Delphi consultation were conducted among the consensus experts,who were asked to score their agreement using Likert scale to the items in the initial recommended definition and the definition statements of palliative care and hospice care.Agreement rate of over 80%was considered as reaching consensus for each items.The core expert panel revised the items and the statements of recommended definitions based on the results from Delphi surveys.The final recommended definitions were formulated after feedback from patient and public involvement(PPI)group members.Results The response rates for the first and second round of Delphi surveys were 83.6%and 100.0%,respectively.The agreement rates of the items and statements of the recommended definitions exceeded 90%.Accordingly,the definitions based on Chinese expert consensus are recommended.Palliative care is an active holistic approach aimed at patients of all ages suffering from life-threatening illness and their families and caregivers.It seeks to improve their quality of life by preventing,assessing,and relieving physical,psychological,social,and spiritual suffering.Hospice care is an integral part of palliative care,focusing on holistic care for patients at the end of life and their families and caregivers.Its goal is to help patients to maintain dignity and achieve a good death by alleviating physical,psychological,social,and spiritual distress without intentionally hastening or postponing death,meanwhile improve the quality of life for families and caregivers.Conclusions This study has established the Chinese expert consensus definitions of palliative care and hospice care in China,as well as the relationship between the two.The definitions highlight the holistic nature of palliative care,providing a foundation for discipline development,clinical practice,and public communication.
基金supported by the National Natural Science Foundation of China(Grant No.42471027).
文摘Accurate drought assessment demands thoughtful consideration of drought definition first of all.Drought is commonly defined as a prolonged period of below-average precipitation leading to water shortages that impact ecosystems,agriculture,and human societies.However,meteorologists,hydrologists,and agronomists often use different criteria to define drought,depending on their specific focus areas.For example,hydrologists define drought according to water deficits in some components of the hydrological cycle(such as precipitation,soil moisture,river flow,and groundwater)or its impacts on the level of services provided to public water supply,irrigation,or hydropower demands(Tate and Gustard,2000).Differences in drought definitions may result in great uncertainties in drought assessment(Satoh et al.,2021).We cannot expect the existence of any workable generalized objective definition of drought(Lloyd-Hughes,2014).
文摘BACKGROUND Fever of unknown origin(FUO)remains a diagnostic challenge and was originally defined in 1961.Its classic criteria include fever≥38.3°C(≥101°F)on multiple occasions,fever lasting three weeks or longer,and a diagnosis after one week of inpatient evaluation.However,these criteria may not fully encompass the varied clinical presentations seen in resource-limited settings such as India.The adaptation of FUO definitions to local healthcare contexts is crucial for enhancing diagnostic accuracy and optimizing patient outcomes.AIM To investigate the applicability of revised FUO criteria in a tertiary care setting in India.METHODS This longitudinal-exploratory study at All India Institute of Medical Sciences Rishikesh(January 2018–December 2022)analyzed 228 adult patients with fever≥99.1°F lasting over three days.Patients diagnosed within three days of admission were excluded.Data were collected retrospectively and prospectively using predefined FUO definitions based on durations of nondiagnosis(3-21 days,>21 days),temperature ranges(99.1°F-100.9°F,≥101°F),and hospitalization durations(3-7 days,>7 days).Descriptive statistics and comparative tests(Fisher's exact test,χ2 test)evaluated outcomes across definitions.RESULTS Among the proposed FUO definitions,Definition B(fever lasting 3-21 days,temperatures between 99.1°F-100.9°F,hospitalization>7 days)predominated(40.8%),while only 2.2%met the classical criteria.Notably,36.5%of Definition B patients remained undiagnosed after 7-10 days,despite 94%undergoing diagnostic workups within 21 days.Infection emerged as the leading etiology across definitions,without significant variation in outcomes or mortality during hospitalization(χ2=27.937,P=0.142).CONCLUSION Adapting FUO criteria to local contexts improves diagnostic accuracy and treatment.Definition B(40.8%prevalence)showed practical utility,with higher mortality in patients discharged on empirical'Anti-tuberculosis therapy'.
基金supported by the National Natural Science Foundation of China(42293280,42272031,42250104,42261144668)Strategic Priority Research Program(B)of the Chinese Academy of Sciences(XDB26000000).
文摘The Global Stratotype Section and Point(GSSP)of the base-Wuchiapingian Stage was formally ratified at the Penglaitan section in South China in 2005.However,the riverside GSSP section at Penglaitan and its auxiliary section at Tieqiao have been permanently flooded since 2020.We herein designate an excavated section at Penglaitan as the new GSSP and the Fengshan section as a new Standard Auxiliary Boundary Stratotype(SABS).In addition,we revised the original definition based on a detailed restudy of the conodont succession from the two sections.We define the GSSP of the base-Wuchiapingian by the First Appearance Datum(FAD)of Clarkina postbitteri within the lineage Jinogondolella granti→Clarkina postbitteri→C.dukouensis.It represents a major evolutionary turnover in conodonts from Jinogondolella to Clarkina and marks the end-Guadalupian extinction event.The U-Pb date of 259.51±0.21 Ma from the uppermost part of the Emeishan basalt is adopted for the GLB age.δ13Ccarb chemostratigraphy at the SABS exhibits several excursions between 3‰and 5‰across the GLB interval.Carbonate 87Sr/86Sr ratio is 0.707244 at the GLB.Remarkably,the SABS contains six normal and six reverse geomagnetic polarity zones in the uppermost Capitanian and three in the lowest Wuchiapingian.
文摘This paper puts forword 11 cartographic generalization operator models and introduces their mathematical definitions,and thus a precise mathematical form and quantitative description has been given to these formerly limited qualitative concepts.The meaning of mathematical definition of operators for cartographic generalization and the application prospect in computer_aided cartography (CAC) is stated.ract The Jurassic strata in Jingyan of Sichuan containing the Mamenchinsaurus fauna are dealt with and divided in this paper. The Mamenchisaurus fossils contained there are compared in morphological features and stratigraphically with other types of the genus on by one. The comprehensive analysis show that the Mamenchisaurus fauna of Jingyan appeared in the early Late Jurassic and is primitive in morphology. The results of the morphological identification and stratigraphical study agree with each other. Their evolutionary processes in different apoches of the Late Jurassic also made clear. Key words Jingyan, Sichuan, Mamenchisaurus Fauna, stratigraphy, evolution
文摘BACKGROUND Sessile serrated adenomas(SSAs)are important premalignant lesions that are difficult to detect during colonoscopy due to poor definition,concealment by mucous caps,and flat appearance.High definition(HD)colonoscopy may uniquely aid in the detection of these inconspicuous lesions compared to standard definition(SD)colonoscopes.In the absence of existing clinical guidelines to obligate the use of HD colonoscopy for colorectal cancer screening in average-risk patients,demonstrating the benefit of HD colonoscopy on SSA detection rate(SSADR)may help strengthen the evidence to recommend its use in all settings.AIM To evaluate the benefit of HD colonoscopy compared to SD colonoscopy on SSADR in average-risk patients undergoing screening colonoscopy.METHODS Data from screening colonoscopies for patients aged 50-76 years two years before and two years after the transition from SD colonoscopy to HD colonoscopy at our large,academic teaching center were collected.Patients with symptoms of colorectal disease,positive occult blood test,history of colon polyps,cancer,polyposis syndrome,inflammatory bowel disease or family history of colon cancer or polyps were excluded.Patients whose endoscopists did not perform colonoscopies both before and after scope definition change were also excluded.Differences in individual endoscopist SSADR,average SSADR,and overall SSADR with SD colonoscopy vs HD colonoscopy were also evaluated for significance.RESULTS A total of 3657 colonoscopies met eligibility criteria with 2012 colonoscopies from the SD colonoscopy period and 1645 colonoscopies from the HD colonoscopy period from a pool of 11 endoscopists.Statistically significant improvements of 2.30%in mean SSADR and 2.53%in overall SSADR were noted with HD colonoscopy(P=0.00028 and P=0.00849,respectively).On the individual level,three endoscopists experienced statistically significant benefit with HD colonoscopy(+5.74%,P=0.0056;+4.50%,P=0.0278;+4.84%,P=0.03486).CONCLUSION Our study suggests that HD colonoscopy statistically significantly improves sessile serrated adenoma detection rate in the screening of average risk patients during screening colonoscopy.By improving the detection and removal of these lesions,adoption of HD colonoscopy may reduce the significant premalignant burden of sessile serrated adenomas.
基金supported by the National Natural Science Foundation of China (10972117)
文摘It is known that there exist obivious differences between the two most commonly used definitions of fractional derivatives-Riemann-Liouville （R-L） definition and Caputo definition. The multiple definitions of fractional derivatives in fractional calculus have hindered the application of fractional calculus in rheology. In this paper, we clarify that the R-L definition and Caputo definition are both rheologically imperfect with the help of mechanical analogues of the fractional element model （Scott-Blair model）. We also clarify that to make them perfect rheologically, the lower terminals of both definitions should be put to ∞. We further prove that the R-L definition with lower terminal a →∞ and the Caputo definition with lower terminal a →∞ are equivalent in the differentiation of functions that are smooth enough and functions that have finite number of singular points. Thus we can define the fractional derivatives in rheology as the R-L derivatives with lower terminal a →∞ （or, equivalently, the Caputo derivatives with lower terminal a →∞） not only for steady-state processes, but also for transient processes. Based on the above definition, the problems of composition rules of fractional operators and the initial conditions for fractional differential equations are discussed, respectively. As an example we study a fractional oscillator with Scott-Blair model and give an exact solution of this equation under given initial conditions.
文摘The adaptability of features definition to applications is an essential condition for implementing feature based design. This paper makes attempt to present a hierarchical definition structure of features. The proposed scheme divides feature definition into application level, form level and geometric level, and provides links between different levels with feature semantics interpretation and enhanced geometric face adjacent graph. respectively. The results not only enable feature definition to abate from the specific dependence and become more extensive, but also provide a theoretical foundation for establishing the concurrent feature based design process model.
文摘Benefiting from advances in feature technology for design and manufacture can not be expected before a formal methodology is established. This paper makes attempt to establish a definition formalism of machining features in design for manufacturability from two aspects: formal definition and manufacturability analysis. Some definitions for machining feature based upon the selection and sequencing of material removal operations for component in accordance with the design geometry are presented and a framework of feature based design for manufacturability is outlined correspondingly. The proposed scheme contributes to several aspects of feature based CAD/CAM integration, especially to encourage potentially a more generic approach to the automation of design.
基金supported by NSFC under the grant number 10972117
文摘During the last two decades fractional calculus has been increasingly applied to physics, especially to rheology.It is well known that there are obivious differences between Riemann-Liouville (R-L) definition and Caputo definition,which are the two most commonly used definitions of fractional derivatives.The multiple definitions of fractional derivatives have hindered the application of fractional calculus in rheology.In this paper,we clarify that the R-L definition and Caputo definition are both Theologically unreasonable with the help of the mechanical analogues of the fractional element model.We also find that to make them more reasonable Theologically,the lower terminals of both definitions should be put to—∞.We further prove that the R-L definition with lower terminal—∞and the Caputo definition with lower terminal—∞are equivalent in the differentiation of functions that are smooth enough and functions that have finite number of singular points.Thus we can define the fractional derivatives in rheology as the R-L derivatives with lower terminal—∞(or,equivalently,the Caputo derivatives with lower terminal—∞) not only for steady-state processes,but also for transient processes.
基金National Natural Science Foundation of China,No.41261016,No.41561016Opening Foundation Projection of State Key Laboratory of Cryosphere Sciences,CAS,No.SKLCS-OP-2016-10+1 种基金Youth Scholar Scientific Capability Promoting Project of Northwest Normal University,No.NWNU-LKQN-14-4Geological Survey Project of China Geological Survey,No.DD2016034206
文摘Glacial lakes are not only the important refresh water resources in alpine region, but also act as a trigger of many glacial hazards such as glacial lake outburst flood （GLOF） and debris flow. Therefore, glacial lakes play an important role on the cryosphere, climate change and alpine hazards. In this paper, the issues of glacial lake were systematically discussed, then from the view of glacial lake inventory and glacial lake hazards study, the glacial lake was defined as natural water mainly supplied by modern glacial meltwater or formed in glacier moraine＇s depression. Furthermore, a complete classification system of glacial lake was proposed based on its formation mechanism, topographic feature and geographical position. Glacial lakes were classified as 6 classes and 8 subclasses, i.e., glacial erosion lake （including cirque lake, gla- cial valley lake and other glacial erosion lake）, moraine-dammed lake （including end mo- raine-dammed lake, lateral moraine-dammed lake and moraine thaw lake）, ice-blocked lake （including advancing glacier-blocked lake and other glacier-blocked lake）, supraglacial lake, subglacial lake and other glacial lake. Meanwhile, some corresponding features exhibiting on remote sensing image and quantitative indices for identifying different glacial lake types were proposed in order to build a universal and operational classification system of glacial lake.
文摘BACKGROUND:A number of definitions have been used for delayed gastric emptying(DGE) after pancreatoduodenectomy and the reported rates varied widely.The International Study Group of Pancreatic Surgery(ISGPS) definition is the current standard but it is not used universally.In this comprehensive review,we aimed to determine the acceptance rate of ISGPS definition of DGE,the incidence of DGE after pancreatoduodenectomy and the effect of various technical modifications on its incidence.DATA SOURCE:We searched PubM ed for studies regarding DGE after pancreatoduodenectomy that were published from 1 January 1980 to 1 July 2015 and extracted data on DGE definition,DGE rates and comparison of DGE rates among different technical modifications from all of the relevant articles.RESULTS:Out of 435 search results,178 were selected for data extraction.The ISGPS definition was used in 80% of the studies published since 2010 and the average rates of DGE and clinically relevant DGE were 27.7%(range:0-100%;median:18.7%) and 14.3%(range:1.8%-58.2%;median:13.6%),respectively.Pylorus preservation or retrocolic reconstruction were not associated with increased DGE rates.Although pyloric dilatation,Braun’s entero-enterostomy and Billroth Ⅱ reconstruction were associated with significantly lower DGE rates,pyloric ring resection appears to be most promising with favorable results in 7 out of 10 studies.CONCLUSIONS:ISGPS definition of DGE has been used in majority of studies published after 2010.Clinically relevant DGE rates remain high at 14.3% despite a number of proposed surgical modifications.Pyloric ring resection seems to offer the most promising solution to reduce the occurrence of DGE.
基金Supported by the Dutch Research Council(NWO)research programme Vidi project,No.91719343。
文摘BACKGROUND Despite the emerging knowledge about colorectal anastomotic leakage(CAL)through the increasing number of clinical and experimental studies, there is no generally accepted definition of CAL. Because of the wide variety of definitions used in literature, comparison of study outcomes and quality of care is complicated.AIM To reach consensus on the definition of CAL using a modified Delphi method.METHODS The RAND/UCLA appropriateness method was used. The expert panel consisted of international colorectal surgeons and researchers who had published three or more articles about CAL. The consensus process consisted of two online distributed questionnaires and a third round with a recommendation. In the questionnaires participants were asked to rate the appropriateness of statements using a 1-9 Likert scale. Consensus was defined as a panel median between 1-3 or 7-9 without disagreement. In the final round a recommendation was formed regarding the definition of CAL and the expert panel was asked if they agreed or disagreed.RESULTSTwenty-three authors participated in the first round and twenty-one finished the second round. After two rounds consensus was reached on 37 items(80%) in nine different categories. The International Study Group of Rectal Cancer definition is the most frequently advised general definition by our panel. Consensus was reached regarding the clinical symptoms of CAL, which serum markers contributes to the suspicion of CAL, which radiological and perioperative findings should be considered as CAL, which grading system is appropriate and if there should be a range of postoperative days in the definition. Eventually, 19 experts completed all three rounds of which 16(84%) agreed with our final recommendations for the definition of CAL.CONCLUSION A consensus-based recommendation for the definition of CAL was formed using our modified Delphi method that can be widely incorporated in the field.
基金the Chair of GIScience,University of Heidelberg and the Klaus-Tschira Foundation (KTS) Heidelberg
文摘Car routing solutions are omnipresent and solutions for pedestrians also exist.Furthermore,public or commercial buildings are getting bigger and the complexity of their internal structure has increased.Consequently,the need for indoor routing solutions has emerged.Some prototypes are available,but they still lack semantically-enriched modelling (e.g.,access constraints,labels,etc.) and are not suitable for providing user-adaptive length-optimal routing in complex buildings.Previous approaches consider simple rooms,concave rooms,and corridors,but important characteristics such as distinct areas in huge rooms and solid obstacles inside rooms are not considered at all,although such details can increase navigation accuracy.By formally defining a weighted indoor routing graph,it is possible to create a detailed and user-adaptive model for route computation.The defined graph also contains semantic information such as room labels,door accessibility constraints,etc.Furthermore,one-way paths inside buildings are considered,as well as three-dimensional building parts,e.g.,elevators or stairways.A hierarchical structure is also possible with the presented graph model.
