Post-traumatic stress disorder(PTSD)is a psychiatric disorder caused by traumatic past experiences,rooted in the neurocircuits of fear memory formation.Memory processes include encoding,storing,and recalling to forget...Post-traumatic stress disorder(PTSD)is a psychiatric disorder caused by traumatic past experiences,rooted in the neurocircuits of fear memory formation.Memory processes include encoding,storing,and recalling to forgetting,suggesting the potential to erase fear memories through timely interventions.Conventional strategies such as medications or electroconvulsive therapy often fail to provide permanent relief and come with significant side-effects.This review explores how fear memory may be erased,particularly focusing on the mnemonic phases of reconsolidation and extinction.Reconsolidation strengthens memory,while extinction weakens it.Interfering with memory reconsolidation could diminish the fear response.Alternatively,the extinction of acquired memory could reduce the fear memory response.This review summarizes experimental animal models of PTSD,examines the nature and epidemiology of reconsolidation to extinction,and discusses current behavioral therapy aimed at transforming fear memories to treat PTSD.In sum,understanding how fear memory updates holds significant promise for PTSD treatment.展开更多
BACKGROUND Fear-related disorders,such as post-traumatic stress disorder(PTSD),significantly impact patients and families.Exposure therapy is a common treatment,but imp-roving its effectiveness remains a key challenge...BACKGROUND Fear-related disorders,such as post-traumatic stress disorder(PTSD),significantly impact patients and families.Exposure therapy is a common treatment,but imp-roving its effectiveness remains a key challenge.Fear conditioning and extinction in animal models offer insights into its mechanisms.Our previous research indi-cates that DNA methyltransferases play a role in fear memory renewal.AIM To investigate the role of DNA methylation in the extinction of fear memory,with the goal of identifying potential strategies to enhance the efficacy of exposure therapy for fear-related disorders.METHODS This study investigated the role of DNA methylation in fear memory extinction in mice.DNA methylation was manipulated using N-phthalyl-L-tryptophan(RG108)to reduce methylation and L-methionine injections to enhance it.Neuronal activity,and dendritic spine density was measured following extinction training.RESULTS RG108 suppressed extinction,reduced spine density,and inhibited neuronal activity.Methionine injections facilitated extinction.CONCLUSION DNA methylation is crucial for fear memory extinction.Enhancing methylation may improve the efficacy of exposure therapy,offering a potential strategy to treat fear-related disorders.展开更多
In this paper,based on the SVIQR model we develop a stochastic epidemic model with multiple vaccinations and time delay.Firstly,we prove the existence and uniqueness of the global positive solution of the model,and co...In this paper,based on the SVIQR model we develop a stochastic epidemic model with multiple vaccinations and time delay.Firstly,we prove the existence and uniqueness of the global positive solution of the model,and construct suitable functions to obtain sufficient conditions for disease extinction.Secondly,in order to effectively control the spread of the disease,appropriate control strategies are formulated by using optimal control theory.Finally,the results are verified by numerical simulation.展开更多
Prevailing concerns on mountainous biodiversity are concentrated on the impacts of climate change at higher elevations. However, the lower elevations are facing additional human disturbance and are expected to suffer ...Prevailing concerns on mountainous biodiversity are concentrated on the impacts of climate change at higher elevations. However, the lower elevations are facing additional human disturbance and are expected to suffer from higher extinction risk but have attracted less conservation attention. Here, we employed population genomics to compare extinction risk two common songbirds—the Vinous-throated Parrotbill (Sinosuthora webbiana) and the Rufous-capped Babbler (Cyanoderma ruficeps)—at lower and higher elevations on the Taiwan island. As the result, we observed decreased genetic diversity and increased genetic load and thus elevated extinction risk in the low-elevation populations of both birds in the eastern slope of the Central Mountains on the Taiwan island. In contrast, genetic-load patterns of both birds in the western slope might be confused by substantial gene flow across lower and higher elevations. These results, on the one hand, call for conservation efforts to lower elevations in mountains and, on the other hand, highlight the importance of population connection in maintaining population viability under impending global change.展开更多
Nested subset pattern(nestedness)is an important part of the theoretical framework of island biogeography and community ecology.However,most previous studies often used nestedness metrics or randomization algorithms t...Nested subset pattern(nestedness)is an important part of the theoretical framework of island biogeography and community ecology.However,most previous studies often used nestedness metrics or randomization algorithms that are vulnerable to type I error.In this study,we inves-tigated the nestedness of lizard assemblages on 37 islands in the Zhoushan Archipelago,China.We used the line-transect method to survey species occurrence,abundance,and habitat types of lizards on 37 islands during 2 breeding seasons in 2021 and 2022.We applied the nested metric WNODF and the conservative rc null model to control for type I error and quantify the significance of nestedness.Spearman rank cor relations were used to evaluate the role of 4 habitat variables(island area,2 isolation indices,and habitat diversity)and 4 ecological traits(body size,geographic range size,clutch size,and minimum area requirement)in generating nestedness.The results of WNODF analyses showed that lizard assemblages were significantly nested.The habitat-by-site matrix estimated by the program NODF was also significantly nested,support-ing the habitat nestedness hypothesis.The nestedness of lizard assemblages were significantly correlated with island area,habitat diversity.clutch size,and minimum area requirement.Overall,our results suggest that selective extinction and habitat nestedness were the main drivers of lizard nestedness in our system.In contrast,the nestedness of lizard assemblages was not due to passive sampling or selective colonization.To maximize the number of species preserved,our results indicate that we should protect both large islands with diverse habitats and species with largearea requirement and clutch size.展开更多
The miniaturization of organisms during the Permian-Triassic mass extinction,as an ecological strategy in response to environmental devastation,has been widely recognized in diverse marine invertebrates.Previous studi...The miniaturization of organisms during the Permian-Triassic mass extinction,as an ecological strategy in response to environmental devastation,has been widely recognized in diverse marine invertebrates.Previous studies on the extinction process and miniaturization of foraminifers in the Permian-Triassic interval have relied on the fossil record of the low-latitude Paleotethys or a global database,although data and materials from the high-latitude Neotethys region are still rare.To reveal the evolutionary patterns and spatial variability of foraminifers at different latitudes and paleogeographic contexts,here we investigated the fossil distribution and size variation of foraminifers in the Selong Section of southern Xizang,located in the mid-latitude Neotethys of the Southern Hemisphere during the Permian-Triassic transition.The results show that the foraminifer of the Selong Section experienced a two-pulsed extinction(total species extinction rate of 71%),consistent with the time in South China but with a lower magnitude of extinction.Meanwhile,the data show that foraminiferal test volume was significantly miniaturized following the first pulse of extinction event:the mean size of post-extinction foraminifer was only 15%of that in the pre-extinction,mainly reflected by the disappearance of large forms as well as occurrences of smaller survivors and originators.Combined with the South China record,size data from southern Xizang indicate that the miniaturization of foraminifera is synchronous in the Paleotethys and Neotethys but smaller in magnitude in the Neotethys.We propose that ocean anoxia and acidification may be the environmental pressures leading to local and global foraminiferal miniaturizations,along with global warming,which might play a dominant role.展开更多
Avian extinctions have been relatively well documented in modern history,and in the past millennia,more bird species are known to have gone extinct than species in any other vertebrate class.We examined the biological...Avian extinctions have been relatively well documented in modern history,and in the past millennia,more bird species are known to have gone extinct than species in any other vertebrate class.We examined the biological correlates of extinction timing among 216 bird species that recently were either observed to go extinct or dis-appeared since 1500 CE,performing a novel analysis for examining the extinction trends of birds by modelling traits against the number of years since present day during which species have been extinct.We analyzed a broad range of traits and characteristics that have previously been associated with extinction and extinction risk in birds and compared the effects of these traits simultaneously against one another.In order to provide a more comprehensive and robust assessment of trait-based drivers of global bird loss in comparison to prior studies,we included extinct species recognized by any of the three major avian taxonomies as well as those birds that lack recent confirmed sightings and are at least functionally extinct.We found that insular,flightless,larger-bodied,ecologically specialized species,as well as those with high aspect ratio wings,were likely to go extinct earlier in time.Besides identifying the key locations and time periods over the past five centuries where birds have gone extinct,and highlighting specific extinction-prone taxonomic groups,we provide a complete and unified dataset of traits used in this study that helps address the lack of extensive public data on modern extinct species.展开更多
Fear extinction is a biological process in which learned fear behavior diminishes without anticipated reinforcement,allowing the organism to re-adapt to ever-changing situations.Based on the behavioral hypothesis that...Fear extinction is a biological process in which learned fear behavior diminishes without anticipated reinforcement,allowing the organism to re-adapt to ever-changing situations.Based on the behavioral hypothesis that extinction is new learning and forms an extinction memory,this new memory is more readily forgettable than the original fear memory.The brain’s cellular and synaptic traces underpinning this inherently fragile yet reinforceable extinction memory remain unclear.Intriguing questions are about the whereabouts of the engram neurons that emerged during extinction learning and how they constitute a dynamically evolving functional construct that works in concert to store and express the extinction memory.In this review,we discuss recent advances in the engram circuits and their neural connectivity plasticity for fear extinction,aiming to establish a conceptual framework for understanding the dynamic competition between fear and extinction memories in adaptive control of conditioned fear responses.展开更多
INTRODUCTION Earth scientists have long sought universal features of past extinction crises.It can be argued that each past extinction event was a singularity,caused by combinations of circumstances that are unique in...INTRODUCTION Earth scientists have long sought universal features of past extinction crises.It can be argued that each past extinction event was a singularity,caused by combinations of circumstances that are unique in each case,and therefore that the search for common causes is futile.However,a key feature of the uniformitarian approach to geology is that past processes are the same as modern-day processes and,with that in mind,earth scientists are keen to use their knowledge to contribute some understanding to the study of the present and future climate crisis.展开更多
This article introduces a method of achieving high polarization extinction ratio using a subwavelength grating structure on a lithium niobate thin film platform,and the chip is formed on the surface of the lithium nio...This article introduces a method of achieving high polarization extinction ratio using a subwavelength grating structure on a lithium niobate thin film platform,and the chip is formed on the surface of the lithium niobate thin film.The chip,with a length of just 20μm,achieved a measured polarization extinction ratio of 29 dB at 1550 nm wavelength.This progress not only proves the possibility of achieving a high extinction ratio on a lithium niobate thin film platform,but also offers important technical references for future work on polarization beam splitters,integrated fiber optic gyroscopes,and so on.展开更多
In this article, we develop and analyze a continuous-time Markov chain (CTMC) model to study the resurgence of dengue. We also explore the large population asymptotic behavior of probabilistic model of dengue using th...In this article, we develop and analyze a continuous-time Markov chain (CTMC) model to study the resurgence of dengue. We also explore the large population asymptotic behavior of probabilistic model of dengue using the law of large numbers (LLN). Initially, we calculate and estimate the probabilities of dengue extinction and major outbreak occurrence using multi-type Galton-Watson branching processes. Subsequently, we apply the LLN to examine the convergence of the stochastic model towards the deterministic model. Finally, theoretical numerical simulations are conducted exploration to validate our findings. Under identical conditions, our numerical results demonstrate that dengue could vanish in the stochastic model while persisting in the deterministic model. The highlighting of the law of large numbers through numerical simulations indicates from what population size a deterministic model should be considered preferable.展开更多
One caveat to the dinosaur’s extinction is the conclusion that avian dinosaurs survived and became ancestors of birds. Their mobility enabled them to migrate great distances and find the nutrients needed to survive. ...One caveat to the dinosaur’s extinction is the conclusion that avian dinosaurs survived and became ancestors of birds. Their mobility enabled them to migrate great distances and find the nutrients needed to survive. Given this scenario, could the current observable migration of birds (the “dinosaurian offspring”) now be related? Migration is the regular seasonal movement undertaken by many species of birds, with the most common pattern, flying north in the Northern spring to breed in the temperate or Arctic summer and returning in the Northern autumn to wintering grounds in warmer regions of the south. The primary motivation for migration appears to be food. None of the major North-South migratory pathways fly over the Caribbean but three main fly ways, past to the west of the theorized K-T impact centre. Due to their ability to fly, the “avian Dinosaurs” adapted and survived very quickly in response to the disaster that marked the K-T boundary. It is an interesting speculation that the avian migration that we witness today is rooted in an event that occurred 66 million years ago! But it does explain why the migratory birds mostly fly from Polar summer to polar summer when they could just be as easily fly from Polar zone to the warmer equatorial region and back. In the recent article in Nature by Melanie During about identifying the late spring timing of the “Astro disaster”, it can be cited as consistent with my speculation. A late April early May Impact as suggested by During would have seen these migrations completely. The western migratory routes would have been found to be “luxurious” in vegetation in that first northern autumn after the “Astro-impact” while all eastern routes would have still been barren.展开更多
At present, the use of furnaces in the northern rural areas of China is very common, due to the insufficient burning of fuel (coal, wood, etc.), carbon monoxide (CO) and other toxic gases are produced, CO colorless an...At present, the use of furnaces in the northern rural areas of China is very common, due to the insufficient burning of fuel (coal, wood, etc.), carbon monoxide (CO) and other toxic gases are produced, CO colorless and odorless, difficult to find in time, and bring huge safety risks to the life and health of residents. Based on the above problems, we developed a gas monitoring and removal device which could reduce the effect of extinction coefficient. The device was composed of ash settling area, gas disturbance area, spectral absorption identification area and gas removal area. After the air entered the device, the large-size particles were first settled to purify the solid particles in the gas, the gas was disturbed through the multi-layer separator to achieve the turbulent production of the gas, and then the gas was identified through the optical element of the direct absorption spectrum technology. When the toxic gas component reached the threshold, the spray device would automatically start for chemical removal to achieve the role of purifying the gas. At the same time, the device’s alarm could be alerted by buzzer and flash to remind users to evacuate in time. By improving the optical device, the effect of extinction coefficient on measurement was reduced and the monitoring accuracy was improved.展开更多
With the method of differential optical absorption spectroscopy （DOAS）, average concentrations of aerosol particles along light path were measured with a flashlight source in Chiba area during the period of one mont...With the method of differential optical absorption spectroscopy （DOAS）, average concentrations of aerosol particles along light path were measured with a flashlight source in Chiba area during the period of one month. The optical thickness at 550 nm is compared with the concentration of ground-measured suspended particulate matter （SPM）. Good correlations are found between the DOAS and SPM data, leading to the determination of the aerosol mass extinction efficiency （MEE） to be possible in the lower troposphere. The average MEE value is about 7.6m^2.g^-1 , and the parameter exhibits a good correlation with the particle size as determined from the wavelength dependence of the DOAS signal intensity.展开更多
Lidar （Light detection and ranging） system monitoring of the atmosphere is a novel and powerful technique tool. The Raman lidar is well established today as a leading research tool in the study of numerous important...Lidar （Light detection and ranging） system monitoring of the atmosphere is a novel and powerful technique tool. The Raman lidar is well established today as a leading research tool in the study of numerous important areas in the atmospheric sciences. In this paper, the principle of Raman lidar technique measurement CO2 concentration profile is presented and the errors caused by molecular and aerosol extinction for CO2 concentration profile measurement with Raman lidar are also presented. The standard atmosphere extinction profile and ＇real-time＇ Hefei area extinction profile are used to conduct correction and the corresponding results are yielded. Simulation results with standard atmosphere mode correction indicate that the errors caused by molecule and aerosol extinction should be counted for the reason that they could reach about 8 ppm and 5 ppm respectively. The relative error caused by Hefei area extinction correction could reach about 6%. The errors caused by the two components extinction influence could produce significant changes for CO2 concentration profile and need to be counted in data processing which could improve the measurement accuracies.展开更多
[Objective] The aim was to study the dynamic variation of extinction coefficient of corn population, so as to improve the accuracy of assessment on net primary productivity （NPP） or yield. [Method] Based on the data...[Objective] The aim was to study the dynamic variation of extinction coefficient of corn population, so as to improve the accuracy of assessment on net primary productivity （NPP） or yield. [Method] Based on the data of photosynthetic active radiation and leaf area index during corn growing season （from May to September） in 2006, observed in Jinzhou observation station of corn farmland ecosystem, China Meteorological Administration, the dynamic variation of extinction coefficient of corn population was analyzed. [Result] There was a great daily variation in the extinction coefficient of corn population during growing season, and the maximum value appeared from 7：00 to 9：00 and from 15：00 to 17：00, while the minimum could be found around 12：00, but the amplitude of variation decreased in tasseling stage. On a large time scale （5 d）, there was a parabolic relationship between extinction coefficient （K） and leaf area index （LAI）, with determination coefficient R2 of 0.960 7. The simulation equation of extinction coefficient, based on the sun elevation angle or leaf area index, had poor accuracy at various time during growing season, so a new dynamic model of extinction coefficient was established, namely K=λ（0.784 8-0.001 6θ）（0.154 8LAI2-0.558 6LAI＋0.654）. [Conclusion] The effect of sun elevation angle and leaf area index on extinction coefficient during corn growing season was considered in the new dynamic model of extinction coefficient, and its simulated result was superior to that of single-factor model.展开更多
The widespread microbialites deposition that followed the End-Permian mass extinction in the Tethyan realm have been intensively studied because of the evidence they provide on the nature of this crisis and its afterm...The widespread microbialites deposition that followed the End-Permian mass extinction in the Tethyan realm have been intensively studied because of the evidence they provide on the nature of this crisis and its aftermath. However, the age of the microbialite event remains controversial. New conodont collection across the Permian–Triassic（P–T） transition from Dajiang（Guizhou Province, South China） in this study enable us to discriminate four conodont zones, in ascending order, they are： Hindeodus parvus zone, Isarcicella lobata zone, Isarcicella isarcica zone and Hindeodus sosioensis zone. The age of microbialite in the P–T transition at the Dajiang Section is considered to be within the Hindeodus parvus zone and thus to clearly post-date the main extinction crisis. Reviewing the age of onset of microbialites throughout the Tethyan regions reveals two different ages： a Hindeodus changxingensis zone age is dominant in south-western and westernmost Tethys, whilst most other regions show microbialite deposition began in the Hindeodus parvus zone. Our investigation also indicates that two conodont changes occur at this time： an increase of hindeodid species immediately following a sequence boundary and the mass extinction, and a phase of extinction losses in the earliest Triassic Isarcicella isarcica zone during highstand development.展开更多
Over the past 500 million years in Earth's history,five mass extinctions("Big Five")have been identified,each with an extinction rate of exceeding 75%of marine species[1].Abrupt climatic and environmenta...Over the past 500 million years in Earth's history,five mass extinctions("Big Five")have been identified,each with an extinction rate of exceeding 75%of marine species[1].Abrupt climatic and environmental changes attributed to intra-or extraterrestrial events were proposed to cause these mass extinctions.Today the world is likely facing an ongoing biotic crisis,the socalled sixth mass extinction[2],due to the accelerated climate and environmental changes resulting from various anthropogenic activities.It is estimated that the average rate of vertebrate species loss in the last century is 100 times greater than the background rate[2].Deciphering the causes and mechanisms of past mass extinctions therefore is of great importance,as it provides critical knowledge for understanding the pattern and underlying mechanism of current biodiversity loss.展开更多
The objective of this study was to reconstruct light extinction coefficients （b ext ） according to chemical composition components of particulate matter up to 2.5 μm in size （PM 2.5 ）. PM 2.5 samples were collect...The objective of this study was to reconstruct light extinction coefficients （b ext ） according to chemical composition components of particulate matter up to 2.5 μm in size （PM 2.5 ）. PM 2.5 samples were collected at the monitoring station of the South China of Institute of Environmental Science （SCIES, Guangzhou, China） during January 2010, and the online absorbing and scattering coefficients were obtained using an aethalometer and a nephelometer. The measured values of light absorption coefficient by particle （b ap ） and light scattering coefficient by particle （b sp ） significantly correlated （R 2 0.95） with values of b ap and b sp that were reconstructed using the Interagency Monitoring of Protected Visual Environments （IMPROVE） formula when RH was 70%. The measured b ext had a good correlation （R 2 0.83） with the calculated b ext under ambient RH conditions. The result of source apportionment of b ext showed that ammonium sulfate [（NH 4 ） 2 SO 4 ] was the largest contributor （35.0%） to b ext , followed by ammonium nitrate （NH 4 NO 3 , 22.9%）, organic matter （16.1%）, elemental carbon （11.8%）, sea salt （4.7%）, and nitrogen dioxide （NO 2 , 9.6%）. To improve visibility in Guangzhou, the effective control of secondary particles like sulfates, nitrates, and ammonia should be given more attention in urban environmental management.展开更多
基金supported by the National Key Research and Development Project of China(2021ZD0202800)the National Natural Science Foundation of China(U21A20418,82003727).
文摘Post-traumatic stress disorder(PTSD)is a psychiatric disorder caused by traumatic past experiences,rooted in the neurocircuits of fear memory formation.Memory processes include encoding,storing,and recalling to forgetting,suggesting the potential to erase fear memories through timely interventions.Conventional strategies such as medications or electroconvulsive therapy often fail to provide permanent relief and come with significant side-effects.This review explores how fear memory may be erased,particularly focusing on the mnemonic phases of reconsolidation and extinction.Reconsolidation strengthens memory,while extinction weakens it.Interfering with memory reconsolidation could diminish the fear response.Alternatively,the extinction of acquired memory could reduce the fear memory response.This review summarizes experimental animal models of PTSD,examines the nature and epidemiology of reconsolidation to extinction,and discusses current behavioral therapy aimed at transforming fear memories to treat PTSD.In sum,understanding how fear memory updates holds significant promise for PTSD treatment.
基金Supported by National Natural Science Foundation of China,No.82360231Yunnan Basic Research Program General Project,No.202401AT070075+1 种基金Dali Basic Research Program Key Project,No.202301A020021Youth Special Project for Basic Research of Local Universities in Yunnan Province,No.202301BA070001-127.
文摘BACKGROUND Fear-related disorders,such as post-traumatic stress disorder(PTSD),significantly impact patients and families.Exposure therapy is a common treatment,but imp-roving its effectiveness remains a key challenge.Fear conditioning and extinction in animal models offer insights into its mechanisms.Our previous research indi-cates that DNA methyltransferases play a role in fear memory renewal.AIM To investigate the role of DNA methylation in the extinction of fear memory,with the goal of identifying potential strategies to enhance the efficacy of exposure therapy for fear-related disorders.METHODS This study investigated the role of DNA methylation in fear memory extinction in mice.DNA methylation was manipulated using N-phthalyl-L-tryptophan(RG108)to reduce methylation and L-methionine injections to enhance it.Neuronal activity,and dendritic spine density was measured following extinction training.RESULTS RG108 suppressed extinction,reduced spine density,and inhibited neuronal activity.Methionine injections facilitated extinction.CONCLUSION DNA methylation is crucial for fear memory extinction.Enhancing methylation may improve the efficacy of exposure therapy,offering a potential strategy to treat fear-related disorders.
基金supported by the Fundamental Research Funds for the Central Universities(No.3122025090)。
文摘In this paper,based on the SVIQR model we develop a stochastic epidemic model with multiple vaccinations and time delay.Firstly,we prove the existence and uniqueness of the global positive solution of the model,and construct suitable functions to obtain sufficient conditions for disease extinction.Secondly,in order to effectively control the spread of the disease,appropriate control strategies are formulated by using optimal control theory.Finally,the results are verified by numerical simulation.
基金supported by the National Natural Science Foundation of China (32170440 and 31772437)the West Light Foundation of the Chinese Academy of Sciencesthe Yunnan Applied Basic Research Project (202401AS070078)
文摘Prevailing concerns on mountainous biodiversity are concentrated on the impacts of climate change at higher elevations. However, the lower elevations are facing additional human disturbance and are expected to suffer from higher extinction risk but have attracted less conservation attention. Here, we employed population genomics to compare extinction risk two common songbirds—the Vinous-throated Parrotbill (Sinosuthora webbiana) and the Rufous-capped Babbler (Cyanoderma ruficeps)—at lower and higher elevations on the Taiwan island. As the result, we observed decreased genetic diversity and increased genetic load and thus elevated extinction risk in the low-elevation populations of both birds in the eastern slope of the Central Mountains on the Taiwan island. In contrast, genetic-load patterns of both birds in the western slope might be confused by substantial gene flow across lower and higher elevations. These results, on the one hand, call for conservation efforts to lower elevations in mountains and, on the other hand, highlight the importance of population connection in maintaining population viability under impending global change.
基金supported by the National Natural Science Foundation of China(31971545 and 32271734).
文摘Nested subset pattern(nestedness)is an important part of the theoretical framework of island biogeography and community ecology.However,most previous studies often used nestedness metrics or randomization algorithms that are vulnerable to type I error.In this study,we inves-tigated the nestedness of lizard assemblages on 37 islands in the Zhoushan Archipelago,China.We used the line-transect method to survey species occurrence,abundance,and habitat types of lizards on 37 islands during 2 breeding seasons in 2021 and 2022.We applied the nested metric WNODF and the conservative rc null model to control for type I error and quantify the significance of nestedness.Spearman rank cor relations were used to evaluate the role of 4 habitat variables(island area,2 isolation indices,and habitat diversity)and 4 ecological traits(body size,geographic range size,clutch size,and minimum area requirement)in generating nestedness.The results of WNODF analyses showed that lizard assemblages were significantly nested.The habitat-by-site matrix estimated by the program NODF was also significantly nested,support-ing the habitat nestedness hypothesis.The nestedness of lizard assemblages were significantly correlated with island area,habitat diversity.clutch size,and minimum area requirement.Overall,our results suggest that selective extinction and habitat nestedness were the main drivers of lizard nestedness in our system.In contrast,the nestedness of lizard assemblages was not due to passive sampling or selective colonization.To maximize the number of species preserved,our results indicate that we should protect both large islands with diverse habitats and species with largearea requirement and clutch size.
基金supported by the State Key R&D Project of China(No.2023YFF0804000)the National Natural Science Foundation of China(Nos.92155201,92255303)a BQR of the Universit'e de Bourgogne。
文摘The miniaturization of organisms during the Permian-Triassic mass extinction,as an ecological strategy in response to environmental devastation,has been widely recognized in diverse marine invertebrates.Previous studies on the extinction process and miniaturization of foraminifers in the Permian-Triassic interval have relied on the fossil record of the low-latitude Paleotethys or a global database,although data and materials from the high-latitude Neotethys region are still rare.To reveal the evolutionary patterns and spatial variability of foraminifers at different latitudes and paleogeographic contexts,here we investigated the fossil distribution and size variation of foraminifers in the Selong Section of southern Xizang,located in the mid-latitude Neotethys of the Southern Hemisphere during the Permian-Triassic transition.The results show that the foraminifer of the Selong Section experienced a two-pulsed extinction(total species extinction rate of 71%),consistent with the time in South China but with a lower magnitude of extinction.Meanwhile,the data show that foraminiferal test volume was significantly miniaturized following the first pulse of extinction event:the mean size of post-extinction foraminifer was only 15%of that in the pre-extinction,mainly reflected by the disappearance of large forms as well as occurrences of smaller survivors and originators.Combined with the South China record,size data from southern Xizang indicate that the miniaturization of foraminifera is synchronous in the Paleotethys and Neotethys but smaller in magnitude in the Neotethys.We propose that ocean anoxia and acidification may be the environmental pressures leading to local and global foraminiferal miniaturizations,along with global warming,which might play a dominant role.
文摘Avian extinctions have been relatively well documented in modern history,and in the past millennia,more bird species are known to have gone extinct than species in any other vertebrate class.We examined the biological correlates of extinction timing among 216 bird species that recently were either observed to go extinct or dis-appeared since 1500 CE,performing a novel analysis for examining the extinction trends of birds by modelling traits against the number of years since present day during which species have been extinct.We analyzed a broad range of traits and characteristics that have previously been associated with extinction and extinction risk in birds and compared the effects of these traits simultaneously against one another.In order to provide a more comprehensive and robust assessment of trait-based drivers of global bird loss in comparison to prior studies,we included extinct species recognized by any of the three major avian taxonomies as well as those birds that lack recent confirmed sightings and are at least functionally extinct.We found that insular,flightless,larger-bodied,ecologically specialized species,as well as those with high aspect ratio wings,were likely to go extinct earlier in time.Besides identifying the key locations and time periods over the past five centuries where birds have gone extinct,and highlighting specific extinction-prone taxonomic groups,we provide a complete and unified dataset of traits used in this study that helps address the lack of extensive public data on modern extinct species.
基金supported by grants from the STI2030-Major Projects(2021ZD0202800)the National Natural Science Foundation of China(32071023 and 32371078)+2 种基金the Program of Shanghai Academic/Technology Research Leader(22XD1420700)the Shanghai Municipal Health Commission(2022XD046)Innovative Research Team of High-Level Local Universities in Shanghai.
文摘Fear extinction is a biological process in which learned fear behavior diminishes without anticipated reinforcement,allowing the organism to re-adapt to ever-changing situations.Based on the behavioral hypothesis that extinction is new learning and forms an extinction memory,this new memory is more readily forgettable than the original fear memory.The brain’s cellular and synaptic traces underpinning this inherently fragile yet reinforceable extinction memory remain unclear.Intriguing questions are about the whereabouts of the engram neurons that emerged during extinction learning and how they constitute a dynamically evolving functional construct that works in concert to store and express the extinction memory.In this review,we discuss recent advances in the engram circuits and their neural connectivity plasticity for fear extinction,aiming to establish a conceptual framework for understanding the dynamic competition between fear and extinction memories in adaptive control of conditioned fear responses.
文摘INTRODUCTION Earth scientists have long sought universal features of past extinction crises.It can be argued that each past extinction event was a singularity,caused by combinations of circumstances that are unique in each case,and therefore that the search for common causes is futile.However,a key feature of the uniformitarian approach to geology is that past processes are the same as modern-day processes and,with that in mind,earth scientists are keen to use their knowledge to contribute some understanding to the study of the present and future climate crisis.
基金Supported by Beijing Natural Science Foundation(4242062)and the Youth Innovation Promotion Association,CAS(2021108)。
文摘This article introduces a method of achieving high polarization extinction ratio using a subwavelength grating structure on a lithium niobate thin film platform,and the chip is formed on the surface of the lithium niobate thin film.The chip,with a length of just 20μm,achieved a measured polarization extinction ratio of 29 dB at 1550 nm wavelength.This progress not only proves the possibility of achieving a high extinction ratio on a lithium niobate thin film platform,but also offers important technical references for future work on polarization beam splitters,integrated fiber optic gyroscopes,and so on.
文摘In this article, we develop and analyze a continuous-time Markov chain (CTMC) model to study the resurgence of dengue. We also explore the large population asymptotic behavior of probabilistic model of dengue using the law of large numbers (LLN). Initially, we calculate and estimate the probabilities of dengue extinction and major outbreak occurrence using multi-type Galton-Watson branching processes. Subsequently, we apply the LLN to examine the convergence of the stochastic model towards the deterministic model. Finally, theoretical numerical simulations are conducted exploration to validate our findings. Under identical conditions, our numerical results demonstrate that dengue could vanish in the stochastic model while persisting in the deterministic model. The highlighting of the law of large numbers through numerical simulations indicates from what population size a deterministic model should be considered preferable.
文摘One caveat to the dinosaur’s extinction is the conclusion that avian dinosaurs survived and became ancestors of birds. Their mobility enabled them to migrate great distances and find the nutrients needed to survive. Given this scenario, could the current observable migration of birds (the “dinosaurian offspring”) now be related? Migration is the regular seasonal movement undertaken by many species of birds, with the most common pattern, flying north in the Northern spring to breed in the temperate or Arctic summer and returning in the Northern autumn to wintering grounds in warmer regions of the south. The primary motivation for migration appears to be food. None of the major North-South migratory pathways fly over the Caribbean but three main fly ways, past to the west of the theorized K-T impact centre. Due to their ability to fly, the “avian Dinosaurs” adapted and survived very quickly in response to the disaster that marked the K-T boundary. It is an interesting speculation that the avian migration that we witness today is rooted in an event that occurred 66 million years ago! But it does explain why the migratory birds mostly fly from Polar summer to polar summer when they could just be as easily fly from Polar zone to the warmer equatorial region and back. In the recent article in Nature by Melanie During about identifying the late spring timing of the “Astro disaster”, it can be cited as consistent with my speculation. A late April early May Impact as suggested by During would have seen these migrations completely. The western migratory routes would have been found to be “luxurious” in vegetation in that first northern autumn after the “Astro-impact” while all eastern routes would have still been barren.
文摘At present, the use of furnaces in the northern rural areas of China is very common, due to the insufficient burning of fuel (coal, wood, etc.), carbon monoxide (CO) and other toxic gases are produced, CO colorless and odorless, difficult to find in time, and bring huge safety risks to the life and health of residents. Based on the above problems, we developed a gas monitoring and removal device which could reduce the effect of extinction coefficient. The device was composed of ash settling area, gas disturbance area, spectral absorption identification area and gas removal area. After the air entered the device, the large-size particles were first settled to purify the solid particles in the gas, the gas was disturbed through the multi-layer separator to achieve the turbulent production of the gas, and then the gas was identified through the optical element of the direct absorption spectrum technology. When the toxic gas component reached the threshold, the spray device would automatically start for chemical removal to achieve the role of purifying the gas. At the same time, the device’s alarm could be alerted by buzzer and flash to remind users to evacuate in time. By improving the optical device, the effect of extinction coefficient on measurement was reduced and the monitoring accuracy was improved.
基金Project supported by National Natural Science Foundation of China （Grant No 10274080）.
文摘With the method of differential optical absorption spectroscopy （DOAS）, average concentrations of aerosol particles along light path were measured with a flashlight source in Chiba area during the period of one month. The optical thickness at 550 nm is compared with the concentration of ground-measured suspended particulate matter （SPM）. Good correlations are found between the DOAS and SPM data, leading to the determination of the aerosol mass extinction efficiency （MEE） to be possible in the lower troposphere. The average MEE value is about 7.6m^2.g^-1 , and the parameter exhibits a good correlation with the particle size as determined from the wavelength dependence of the DOAS signal intensity.
文摘Lidar （Light detection and ranging） system monitoring of the atmosphere is a novel and powerful technique tool. The Raman lidar is well established today as a leading research tool in the study of numerous important areas in the atmospheric sciences. In this paper, the principle of Raman lidar technique measurement CO2 concentration profile is presented and the errors caused by molecular and aerosol extinction for CO2 concentration profile measurement with Raman lidar are also presented. The standard atmosphere extinction profile and ＇real-time＇ Hefei area extinction profile are used to conduct correction and the corresponding results are yielded. Simulation results with standard atmosphere mode correction indicate that the errors caused by molecule and aerosol extinction should be counted for the reason that they could reach about 8 ppm and 5 ppm respectively. The relative error caused by Hefei area extinction correction could reach about 6%. The errors caused by the two components extinction influence could produce significant changes for CO2 concentration profile and need to be counted in data processing which could improve the measurement accuracies.
基金Supported by Major Project of Chinese National Programs for Fundamental Research and Development(2006CB400502)National Natural Science Funds for Distinguished Young Scholar(40625015)~~
文摘[Objective] The aim was to study the dynamic variation of extinction coefficient of corn population, so as to improve the accuracy of assessment on net primary productivity （NPP） or yield. [Method] Based on the data of photosynthetic active radiation and leaf area index during corn growing season （from May to September） in 2006, observed in Jinzhou observation station of corn farmland ecosystem, China Meteorological Administration, the dynamic variation of extinction coefficient of corn population was analyzed. [Result] There was a great daily variation in the extinction coefficient of corn population during growing season, and the maximum value appeared from 7：00 to 9：00 and from 15：00 to 17：00, while the minimum could be found around 12：00, but the amplitude of variation decreased in tasseling stage. On a large time scale （5 d）, there was a parabolic relationship between extinction coefficient （K） and leaf area index （LAI）, with determination coefficient R2 of 0.960 7. The simulation equation of extinction coefficient, based on the sun elevation angle or leaf area index, had poor accuracy at various time during growing season, so a new dynamic model of extinction coefficient was established, namely K=λ（0.784 8-0.001 6θ）（0.154 8LAI2-0.558 6LAI＋0.654）. [Conclusion] The effect of sun elevation angle and leaf area index on extinction coefficient during corn growing season was considered in the new dynamic model of extinction coefficient, and its simulated result was superior to that of single-factor model.
基金supported by the Natural Science Foundation of China (Nos. 41172024, 41272044)the "973" Program (No. 2011CB808800)+2 种基金the "111" Project (No. B08030)the ‘Fundamental Research Funds for the Central Universities,China University of Geosciences (Wuhan)the State Key Laboratory of Biogeology and Environmental Geology, China University of Geosciences (No. GBL11202)
文摘The widespread microbialites deposition that followed the End-Permian mass extinction in the Tethyan realm have been intensively studied because of the evidence they provide on the nature of this crisis and its aftermath. However, the age of the microbialite event remains controversial. New conodont collection across the Permian–Triassic（P–T） transition from Dajiang（Guizhou Province, South China） in this study enable us to discriminate four conodont zones, in ascending order, they are： Hindeodus parvus zone, Isarcicella lobata zone, Isarcicella isarcica zone and Hindeodus sosioensis zone. The age of microbialite in the P–T transition at the Dajiang Section is considered to be within the Hindeodus parvus zone and thus to clearly post-date the main extinction crisis. Reviewing the age of onset of microbialites throughout the Tethyan regions reveals two different ages： a Hindeodus changxingensis zone age is dominant in south-western and westernmost Tethys, whilst most other regions show microbialite deposition began in the Hindeodus parvus zone. Our investigation also indicates that two conodont changes occur at this time： an increase of hindeodid species immediately following a sequence boundary and the mass extinction, and a phase of extinction losses in the earliest Triassic Isarcicella isarcica zone during highstand development.
基金supported by the National Natural Science Foundation of China(42025703,42325202,and 42277072)。
文摘Over the past 500 million years in Earth's history,five mass extinctions("Big Five")have been identified,each with an extinction rate of exceeding 75%of marine species[1].Abrupt climatic and environmental changes attributed to intra-or extraterrestrial events were proposed to cause these mass extinctions.Today the world is likely facing an ongoing biotic crisis,the socalled sixth mass extinction[2],due to the accelerated climate and environmental changes resulting from various anthropogenic activities.It is estimated that the average rate of vertebrate species loss in the last century is 100 times greater than the background rate[2].Deciphering the causes and mechanisms of past mass extinctions therefore is of great importance,as it provides critical knowledge for understanding the pattern and underlying mechanism of current biodiversity loss.
基金supported by the Special Scientific Research Funds for Environment Protection Commonweal Section (Grant Nos 200809143 and 201009001)Knowledge Innovation Program of the Chinese Academy of Sciences (Grant No IAP09320)
文摘The objective of this study was to reconstruct light extinction coefficients （b ext ） according to chemical composition components of particulate matter up to 2.5 μm in size （PM 2.5 ）. PM 2.5 samples were collected at the monitoring station of the South China of Institute of Environmental Science （SCIES, Guangzhou, China） during January 2010, and the online absorbing and scattering coefficients were obtained using an aethalometer and a nephelometer. The measured values of light absorption coefficient by particle （b ap ） and light scattering coefficient by particle （b sp ） significantly correlated （R 2 0.95） with values of b ap and b sp that were reconstructed using the Interagency Monitoring of Protected Visual Environments （IMPROVE） formula when RH was 70%. The measured b ext had a good correlation （R 2 0.83） with the calculated b ext under ambient RH conditions. The result of source apportionment of b ext showed that ammonium sulfate [（NH 4 ） 2 SO 4 ] was the largest contributor （35.0%） to b ext , followed by ammonium nitrate （NH 4 NO 3 , 22.9%）, organic matter （16.1%）, elemental carbon （11.8%）, sea salt （4.7%）, and nitrogen dioxide （NO 2 , 9.6%）. To improve visibility in Guangzhou, the effective control of secondary particles like sulfates, nitrates, and ammonia should be given more attention in urban environmental management.
