This paper investigates a conservator’s approach to a particular subset of physical cultural property:clocks.It looks at established conservation frameworks and practical elements of codes of practice,and considers h...This paper investigates a conservator’s approach to a particular subset of physical cultural property:clocks.It looks at established conservation frameworks and practical elements of codes of practice,and considers how the conservator’s perspective will differ from that of a peer engaged solely with an approach to static objects.The paper considers,through examples of historic technological development,how what we mean by"clock"and how we consider clocks are in a state of constant change of context.Clocks are a diverse group of objects,some of which are technically complex.The conservator must draw together many influences in order to demonstrate professional competence in thinking,delivering an accountable decision-making process.In order to illustrate the breadth of the challenge the conservator faces when approaching clocks,the paper gives examples of three contrasting case study objects including one automaton and one electromechanical model.Clocks as a group comprise multimedia and multimedium objects.The perspective of the conservator will draw on professional networks within and without the immediate field,including at times the work of philosophers,scientists,sociologists,and historians in order to maintain objectivity,inform and engender new ideas.The paper concludes with the statement that the perspective of the conservator engaged with clocks should never be fixed,and that solutions to the challenges presented by clocks are never absolute and never permanent,but are in constant context-driven flux.展开更多
Aconitum heterophyllum Wall.ex Royle,an endangered Ayurvedic medicinal plant,is predominantly found in the alpine and subalpine zones of the Himalayas.This study aimed to enhance seed germination under various soil co...Aconitum heterophyllum Wall.ex Royle,an endangered Ayurvedic medicinal plant,is predominantly found in the alpine and subalpine zones of the Himalayas.This study aimed to enhance seed germination under various soil conditions,to facilitate conservation and provide opportunities for income generation through large-scale cultivation.The selection of soil treatments was based on their contrasting physicochemical properties and known influence on seed germination in related high altitude species.The study was conducted in a mist chamber at the Deoban nursery in Dehradun,India,using five soil conditions:normal forest soil(NS),vermiculite(Vc),vermiculite+normal forest soil(Vc+NS),normal forest soil+sand(NS+S),and a mixture of soil,sand,vermiculite,and vermicompost(NS+S+Vc+VCo).All the soil treatments were replicated ten times under the controlled environmental conditions.These substrates were selected to represent a gradient of water retention,aeration,nutrient content,and organic matter composition,which are known to affect seed germination and early seedling development.Results showed significant different among treatments in terms of physical and chemical soil properties in sand,silt,clay,pH,organic carbon,organic matter,total nitrogen,total phosphorus,as well as growth parameters such as,seed vigor index,root length,plant length,and leaf number across soil conditions.Among all treatments,vermiculite alone showed the highest germination rate(73.33%),peak germination value(0.719),and seed vigor index(24.02),along with superior growth parameters and the lowest seed mortality index(2.45).These findings in addition to its low seed mortality underscore vermiculite's potential as a suitable growth medium for the ex-situ cultivation of A.heterophyllum offering a promising alternative to wild harvesting while supporting conservation and sustainable use of this valuable Himalayan species.展开更多
Successful ex situ conservation of plant populations requires a high degree of genetic representativeness.However,spatially biased sampling in ex situ conservation efforts may fail to capture all wild genetic clusters...Successful ex situ conservation of plant populations requires a high degree of genetic representativeness.However,spatially biased sampling in ex situ conservation efforts may fail to capture all wild genetic clusters for species with range-wide genetic structure.To investigate the extent of spatially biased sampling in living collections and the coverage of wild genetic clusters in plant populations under ex situ conservation worldwide,we combined a global synthesis of ex situ conservation efforts with a case study of an endangered riparian plant species,Myricaria laxiflora.Our analysis of ex situ conservation worldwide revealed that the majority(82.6%)of ex situ populations fail to cover all wild genetic clusters,largely due to spatially biased sampling with low geographic coverage.Our case study of M.laxiflora showed that genetic diversity differed between the ex situ and upstream populations,while it was comparable between ex situ populations and other wild populations.However,current ex situ populations did not cover all wild genetic clusters,as the upstream genetic cluster was previously uncollected.Our study suggests that the failure to cover all wild genetic clusters in ex situ populations is a widespread issue,and ex situ populations with high genetic diversity can also fail to cover all wild genetic clusters.In future ex situ conservation programs,both the importance of high genetic diversity and the high coverage of wild genetic clusters should be prioritized.展开更多
African drylands occupied 19.6 million km~2(46%of the total global area)and 525 million people.Soil erosion models are useful for assessing the impact of soil erosion in the dryland areas.This review provides an asses...African drylands occupied 19.6 million km~2(46%of the total global area)and 525 million people.Soil erosion models are useful for assessing the impact of soil erosion in the dryland areas.This review provides an assessment of soil erosion/deposition models and soil conservation practices,which are supportive for mitigating the impact of soil erosion and maintaining soil health and soil functional services for food security in African drylands.The theories of soil erosion models and soil conservation practices provide advanced ways to understand the detailed impact of soil erosion and management solutions.The paper reviews a set of useful soil erosion models and traditional conservation practices,which can control soil erosion and enhance dryland farming systems in Africa.Soil erosion models are classified into three categories:empirical,conceptual,and physical.Soil conservation practices include reduced tillage,advanced cover crops,mechanical structures(barriers made of stones/gravel/vegetation),advanced mechanical roller-crimper technique,mixed cropping,intercropping,crop rotation systems,terracing techniques,and land modification techniques.These conservation practices are effective in controlling soil erosion,reducing soil damage,improving soil health and quality,enhancing soil fertility,and ensuring food security.The existing assessment suggests that understanding the theories of soil erosion models and soil conservation practices is a first step towards addressing soil erosion problems in African drylands.展开更多
Background:We present a case of two major complications following insertion of a nephrostomy managed in a minimally invasive way.Our case is the first in the literature to describe this minimally invasive treatment te...Background:We present a case of two major complications following insertion of a nephrostomy managed in a minimally invasive way.Our case is the first in the literature to describe this minimally invasive treatment technique for colon perforation in a completely asymptomatic patient.Case Description:A 75-year-old female patient with a history of bilateral obstructive uropathy secondary to bilateral radiation-induced ureteric strictures attended for bilateral nephrostomy placement.The patient had a history of endometrial cancer,treated previously by total hysterectomy and bilateral salpingo-oophorectomy with adjuvant chemo-radiotherapy and brachytherapy.Her recovery had been further complicated by the development of radiation cystitis,small bowel resection,and short gut syndrome.The strictures had previously been managed with bilateral double J stents,which have now failed.A left-sided nephrostomy insertion was performed.ACT-scan prompted by a repeat deterioration in renal function revealed a right-sided hydronephrosis and suggested transcolic passage of the previously placed leftsided nephrostomy.She had remained clinically well and apyretic.A right-sided nephrostomy was inserted,and the left re-sited following a colonoscopy-guided nephrostomy removal and clip occlusion of the nephrostomy tract.The patient then developed a pseudoaneurysm,which was managed with embolization.The patient was able to return home with corrected kidney function.The three-monthly checks for changes in nephrostomy catheters did not reveal any complications.Conclusions:The patient therefore presented with two major complications of nephrostomy placement:colonic perforation and pseudoaneurysm,classified as Clavien IIIb and IIIa,respectively.Multidisciplinary management,including urologists,gastroenterologists,general surgeons,and radiologists,enabled a minimally invasive management.Minimally invasive management with endoscopic clip placement appears to be a safe alternative to directed fistula of colonic perforation.展开更多
Bhutan is a biodiverse country,yet there are relatively few scientific studies on its herpetofauna.To determine research gaps and opportunities for scientific advances,we completed a literature review on amphibians an...Bhutan is a biodiverse country,yet there are relatively few scientific studies on its herpetofauna.To determine research gaps and opportunities for scientific advances,we completed a literature review on amphibians and reptiles of Bhutanese origin from online databases including ResearchGate,Google Scholar,the Integrated Taxonomic Information System(ITIS),and relevant authors.Of the 63 studies on herpetofauna of Bhutan between 1972 and 2022,most focused on reptiles(45%)followed by amphibians(32%),while fewer(23%)included both taxa.Most studies were field-based(n=44),followed by desktop research(n=14),and then laboratory work(n=5).Ecology and natural history studies(n=35)dominated the literature,while other disciplines included conservation and anthropogenic interactions(n=22),then evolution,taxonomy,and systematics(n=4).Single reports existed on disease,and on genetic studies.After 2009,the quantity of literature rose considerably to a total of 52 publications on Bhutanese herpetofauna.Most studies have been conducted by Bhutanese researchers(n=36),followed by collaborations with scientists from outside the country(n=15),and work published by foreign scientists alone(n=12)contributed some of the earliest studies.There was a bias in the taxa studied,the type of research,and the location of study.Research concentrating on anatomy or physiology was absent,while studies on disease,genetics,taxonomy,and systematic classification are scarce.There is a pressing need for increased conservation-oriented studies,as they were poorly represented.These gaps offer direction for further research.In particular,there are few studies on the diversity and distribution of amphibians and reptiles-such information is key to analysing threats and developing effective conservation strategies.Such knowledge would contribute greatly towards the conservation and management of Bhutan’s native amphibians and reptiles.Bhutan currently harbours ca.83 amphibian species(31 genera,8 families,3 orders:Anura,Caudata,Gymnophiona)and ca.138 reptile species(58 genera,17 families,2 orders:Squamata,Testudines).Bhutan does have crocodiles,but they are in captivity only.展开更多
Gibbons are small,arboreal apes that play a critical role in tropical biodiversity and ecosystem ecology.However,nearly all species of gibbons are threatened by habitat loss,illegal trade,hunting,and other human activ...Gibbons are small,arboreal apes that play a critical role in tropical biodiversity and ecosystem ecology.However,nearly all species of gibbons are threatened by habitat loss,illegal trade,hunting,and other human activities.Long-term poor understanding of their genetics and evolution undermines effective conservation efforts.In this study,we analyse comparative population genomic data of four Nomascus species.Our results reveal strong genetic differentiation and gene flow among Nomascus species.Additionally,we identify genomic features that are potentially related to natural selection linked to vocalization,fructose metabolism,motor balance,and body size,consistent with the unique phenotype and adaptability of gibbons.Inbreeding,coupled with population declines due to climate change and historical human activities,leads to reduced genetic diversity and the accumulation of deleterious variations that likely affect cardiovascular disease and the reproductive potential of gibbons and further reduce their fitness,highlighting the urgent need for effective conservation strategies.展开更多
Reconciling biodiversity conservation with economic advancement represents a defining challenge of the Anthropocene epoch.Although ecotourism is widely promoted as a strategy capable of delivering both environmental a...Reconciling biodiversity conservation with economic advancement represents a defining challenge of the Anthropocene epoch.Although ecotourism is widely promoted as a strategy capable of delivering both environmental and developmental benefits,empirical evidence regarding its ecological and socioeconomic impacts remains limited.This study critically examined the Hide-in-Bird Pond(HIBP)model,a rapidly expanding,community-based avitourism framework in China that integrates targeted wildlife provisioning with concealed infrastructure for bird observation,simultaneously establishing a novel income source for economically marginalized rural regions through ecotourism.Semi-structured online interviews were conducted with 98 HIBP operators,and thematic analysis was applied to evaluate current developmental patterns,spatial distribution,and conservation outcomes.A total of 251 HIBP sites were identified across China,predominantly located in biodiversity-rich but economically marginalized regions.These sites collectively supported 524 bird species—36%of China's avifauna—including 148 species classified as nationally protected or threatened(38%of nationally listed bird taxa).These findings suggest that HIBP can serve as an integrative socio-ecological platform that aligns conservation objectives with sustainable rural development.However,the absence of standardized governance frameworks and ecological safeguards poses significant risks to biodiversity an d long-term sustainability.Implementation of science-based adaptive management systems,incorporating systematic biodiversity monitoring,inclusive stakeholder coordination,and certified sustainable tourism protocols,is critical to ensure ecological integrity and sectoral resilience.These findings offer novel insights into aligning conservation objectives with economic development across regions characterized by high biodiversity and persistent economic disadvantage.展开更多
Lichens exhibit exceptional ecological adaptability,thriving in diverse habitats ranging from temperate forests to extreme environments.They colonize various substrates,including tree bark,rocks,soil,and artificial su...Lichens exhibit exceptional ecological adaptability,thriving in diverse habitats ranging from temperate forests to extreme environments.They colonize various substrates,including tree bark,rocks,soil,and artificial surfaces,playing critical roles as bioindicators of air quality and environmental change.Despite their ecological and economic importance,regions like Pakistan remain underexplored for lichen diversity,leaving significant gaps in knowledge about local lichen flora.This study hypothesizes that the ecological diversity and environmental gradients in the Hazara Division,Khyber Pakhtunkhwa,significantly influence the distribution,composition,and community structure of lichens.Field surveys were conducted from March 2021 to December 2023 across 48 locations in the Hazara Division,covering diverse altitudes,aspects,and vegetation types.Epiphytic lichens were sampled using standardized transect methods with vertical grids on tree stems.Specimens were collected,shade-dried,and identified using chemical spot tests.Multivariate analyses,including TWINSPAN,CCA,and DCA,were employed to examine species-environment relationships.A total of 97 lichen species were identified across 44 genera and 19 families.Physciaceae was the dominant family(24 species).Foliose lichens represented 55%of the total species,highlighting morphological diversity.Among the recorded species,11 were new to Pakistan,and 30 were newly documented for the Himalayan region of Hazara.The study documented 52 host tree species across 36 genera,with Quercus being the most dominant genus.Multivariate analyses identified seven distinct lichen communities.Altitude and road distance emerged as the strongest drivers of lichen distribution,with specific species exhibiting distinct responses to environmental gradients.In DCA ordination the Eigen value was maximum for axis 1,(0.67)followed by axis 2(0.56).The maximum gradients was 5.87 recorded axis 1.Canonical Correspondence Analysis captured 15.09%of the total variation,with significant contributions from altitude,temperature,and substrate type.The per mutation result for all axis were pseudo(F=1.1,P=0.01).The result showed that species,stand and environmental variables were in linear combination with each other.This study provides the first comprehensive assessment of lichen diversity and ecology in the Hazara Division,unveiling significant species-environment relationships and ecological patterns.The findings underscore the importance of multivariate analysis in lichen studies and highlight the region's potential for further ecological and conservation research.展开更多
Dear Editor,Mountain systems have long been refuges for many species,often viewed as"islands"that promote speciation due to geographic isolation(Rahbek et al.,2019).Their high environmental heterogeneity fos...Dear Editor,Mountain systems have long been refuges for many species,often viewed as"islands"that promote speciation due to geographic isolation(Rahbek et al.,2019).Their high environmental heterogeneity fosters centers of endemism,and they harbor over 85%of global species diversity(Zhao et al.,2022).Consequently,mountains are key systems for exploring biodiversity patterns along elevational gradients,where species richness often follows four recognized models:monotonic decrease,unimodal pattern(forward and backward peak patterns),and low plateau followed by a decrease along the elevational gradient(McCain et al.,2010).展开更多
Tajikistan represents a core region of the biodiversity hotspot in Central Asian mountains and has exceptional vascular plant diversity.However,the species diversity of the country faces urgent conservation challenges...Tajikistan represents a core region of the biodiversity hotspot in Central Asian mountains and has exceptional vascular plant diversity.However,the species diversity of the country faces urgent conservation challenges.There has been a lack of a comprehensive and multidimensional assessment to inform strategic conservation planning.Therefore,this study integrated 4 key biodiversity indices including species richness(SR),phylogenetic diversity(PD),threatened species richness(TSR),and endemic species richness(ESR)to map species diversity distribution patterns,identify conservation gaps,and elucidate their effects of climatic factors.This study revealed that species diversity shows a clear trend of decreasing from the western region to the eastern region of Tajikistan.The central–western mountains(specifically the Gissar-Darvasian and Zeravshanian regions)emerge as irreplaceable biodiversity hotspots.However,we found a severe spatial mismatch between these priority areas and the existing protected areas(PAs).Protection coverage for all hotspots was alarmingly low,ranging from 31.00%to 38.00%.Consequently,a critical 64.80%of integrated priority areas fall outside of the current PAs,representing a major conservation gap.This study identified precipitation seasonality and isothermality as the principal drivers,collectively explaining over 50.00%of the diversity variation and suggesting high vulnerability to hydrological shifts.Furthermore,we detected significant geographic sampling bias in the public biodiversity databases,with the most critical hotspot being systematically under-sampled.This study provides a robust scientific basis for conservation action,highlighting the urgent need to strategically expand PAs in the under-protected southwestern region and to mitigate critical sampling gaps through targeted data digitization and field surveys.These measures are indispensable for securing Tajikistan’s unique biodiversity and achieving the Kunming-Montreal Global Biodiversity Framework Target 3(“30×30 Protection”).展开更多
Sikkim,located in the Eastern Himalayan Region,represents one of the 36 globally recognized biodiversity hotspots and harbors an exceptional range of ecosystems within a relatively small geographic area.Over the past ...Sikkim,located in the Eastern Himalayan Region,represents one of the 36 globally recognized biodiversity hotspots and harbors an exceptional range of ecosystems within a relatively small geographic area.Over the past few decades,the region has witnessed rapid urbanization alongside other developmental activities such as hydropower construction,road expansion,mining and infrastructure development.While these processes have contributed to socioeconomic development,they have simultaneously exerted significant pressure on the fragile mountain environment.This review examines the impacts of urbanization on biodiversity in the Sikkim Himalaya drawing attention to the ways in which land-use change due to urbanization,habitat fragmentation and economic development have altered ecological dynamics and threatened biodiversity of this region.The findings of the current study suggest that unplanned urban growth has led to the degradation of forest cover,disruption of ecological corridors thereby diminishing ecosystem resilience of the region.In addition,the current study highlights the challenges of balancing developmental imperatives with environmental conservation in the study area where both ecological integrity and human livelihoods are intricately interdependent.This study highlights the urgent need for integrated land-use planning that incorporates ecological corridors,urban green spaces,and community-based conservation to mitigate biodiversity loss.Strengthened governance, sustainable tourism, invasive species control, and systematic biodiversity monitoring are essential tobalance urban development with ecological integrity. Most importantly, holistic and interdisciplinary approaches arecritical to ensuring that urban growth in the Global Biodiversity Hotspot of the Sikkim Himalaya aligns with globalbiodiversity conservation goals and the Sustainable Development Goals (SDGs).展开更多
This paper presents a geometric perspective that connects reciprocal transformations with multidimensional integrable deformations.By interpreting conservation laws as closed 1-forms,we formalize reciprocal transforma...This paper presents a geometric perspective that connects reciprocal transformations with multidimensional integrable deformations.By interpreting conservation laws as closed 1-forms,we formalize reciprocal transformations as induced local diffeomorphisms on the jet bundle.This allows us to characterize higher-dimensional deformations as systematic fiber bundle extensions,where fiber coordinates are generated by potential functions of the conservation laws.This perspective provides an interpretation for the covariant lifting of Lax pairs to higher dimensions and reveals that auto-Backlund transformations are composite diffeomorphisms.These results are applied to several classical integrable models.展开更多
It is essential to understand how adaptation needs and options differ among stakeholders in protected areas(PAs)to effectively implement climate change(CC)adaptation strategies.Using the Qiangtang PA in Xizang as a ca...It is essential to understand how adaptation needs and options differ among stakeholders in protected areas(PAs)to effectively implement climate change(CC)adaptation strategies.Using the Qiangtang PA in Xizang as a case study,this research examines CC adaptation needs and options from the perspectives of stakeholders across multiple administrative levels,including provincial,prefectural,county authorities,73 protection stations,and 13364 pastoralists residing within the PA.The findings show that stakeholders at the provincial level,as well as those from the Ali and Naqu prefectures and six counties,place greater emphasis on institutional and resource-related needs than on other categories(attention score:7.0-9.3 vs.5.0-7.0).In contrast,stakeholders from the 73 protection stations prioritize technological and capacity-building needs more strongly than other types(attention score:8.0-9.0 vs.4.0-8.0).The 13364 pastoralists assign the highest importance to social needs relative to other categories(attention score:9.0-9.5 vs.3.0-8.0).Most of the eight existing protection measures were found to indirectly support broader climate adaptation efforts.In particular,protective actions addressing fire,pests,and weather-related disasters can be classified as autonomous adaptation,while other measures generate outcomes that enhance adaptation capacity under specific conditions.Adaptation options,grouped into three main types and 13 subcategories,differ across stakeholder groups,although substantial overlap exists between these options and current protective actions,including ecosystem based adaptation strategies,adaptation-related practices,autonomous adaptation measures,and emergency interventions.Overall,these findings highlight the critical role of all stakeholders-especially staff from the 73 protection stations and the 13364 pastoralists-in the effective implementation of adaptation actions within the PA.展开更多
Plants constitute nearly 80%of the planet’s total biomass(Bar-On et al.,2018);however,this vital group is experiencing severe threats,and recent evaluations indicate that approximately 45%of the world's described...Plants constitute nearly 80%of the planet’s total biomass(Bar-On et al.,2018);however,this vital group is experiencing severe threats,and recent evaluations indicate that approximately 45%of the world's described plant species are at risk of extinction(Bachman et al.,2024).The number of plant extinctions has increased by 60%in the last 100 years(Di Marco et al.,2017).Over the past 250 years,571 plant species have gone extinct—more than twice the combined total of extinct birds,mammals,and amphibians(217 species)(Briggs,2019).展开更多
Effective conservation relies on robust assessments;however,the lack of waterbird data in the Yellow River Basin(YRB)has led to an underestimation of key habitat significance.This study addressed this gap by evaluatin...Effective conservation relies on robust assessments;however,the lack of waterbird data in the Yellow River Basin(YRB)has led to an underestimation of key habitat significance.This study addressed this gap by evaluating YRB wetland conservation importance using waterbirds as indicators and applying Ramsar,Important Bird Areas(IBA),and East Asian-Australasian Flyway(EAAF)criteria.We integrated coordinated surveys with citizen science data,creating a framework that tackles data deficiencies along the under-monitored Central Asian Flyway(CAF).Our analysis identified 75 priority wetlands,supporting 15 threatened species and 49 exceeding global/flyway 1%thresholds,highlighting the basin's biodiversity.We observed strong seasonal habitat use,with high-altitude wetlands vital for breeding and migration,and the Yellow River Delta providing year-round refuge.This research also provided data to refine Baer's Pochard population estimates.Alarmingly,one-third of the identified priority areas,primarily rivers and lakes,remain unprotected.To address this,we recommend systematic surveys,enhanced protected areas,OECMs,and targeted wetland restoration.This study underscores the YRB's role in regional conservation and provides essential data for adaptive management,particularly emphasizing the CAF's importance.展开更多
Root nodule symbiosis(RNS)is a mutualistic association formed between nitrogen-fixing rhizobia or Frankia and host plants limited to four orders within Rosid I―Fabales,Fagales,Cucurbitales,and Rosales―which comprise...Root nodule symbiosis(RNS)is a mutualistic association formed between nitrogen-fixing rhizobia or Frankia and host plants limited to four orders within Rosid I―Fabales,Fagales,Cucurbitales,and Rosales―which comprise the so-called‘Nitrogen Fixing Nodulation Clade’(NFNC).The majority of nodulation studies have focused on Leguminosae,given their agricultural and environmental importance,as well as the widespread occurrence of nodulation among members of this family.Endowing cereal crops with nitrogen fixation,like Leguminosae,presents a strategy to reduce the detrimental effects of synthetic fertilizer overuse.Different hypotheses on the origin of RNS have been proposed;however,key genetic innovations underlying the evolution of RNS,even in Leguminosae,have been rarely reported.In this review,we begin by examining current knowledge of genetic innovations―including gene gain,gene loss,and the acquisition or loss of conserved noncoding sequences(CNS)in preexisting genes.We explore the available evidence supporting these genetic innovations underlying the evolution of RNS in Leguminosae and offer the phylogenomics approach that could be applied to uncover these genetic innovations.Finally,we conclude by proposing a model of genetic innovations underlying the evolution of RNS in Leguminosae and consider the potential implications for the development of nitrogen-fixing crops.展开更多
With their intricate vectorial structures in space,optical skyrmions have significantly expanded the landscape of topological optics and light-matter interactions.We theoretically investigate high harmonic generation ...With their intricate vectorial structures in space,optical skyrmions have significantly expanded the landscape of topological optics and light-matter interactions.We theoretically investigate high harmonic generation in crystals driven by optical skyrmions.We find that although the skyrmion number is not conserved,the resulting high-order harmonics can exhibit a distinctive multi-vortex structure,whose features are shaped by both the topology of the optical skyrmions and the rotational symmetry of the crystal.The position of the vortex centers can be effectively tuned by employing different types of optical skyrmions.To elucidate the underlying physics,we develop a multi-absorption channel model based on the conservation laws of spin and orbital angular momentum.Our work explores the role of optical topology in extreme nonlinear light-matter interactions,offering new opportunities for the formation and manipulation of optical vortices and novel structured light fields in the visible and ultraviolet regimes.展开更多
In recent years bird hunting has become a topical issue in public debate in Poland.Some organizations and communities actively engaged in nature conservation efforts propose a complete ban on hunting,arguing it needs ...In recent years bird hunting has become a topical issue in public debate in Poland.Some organizations and communities actively engaged in nature conservation efforts propose a complete ban on hunting,arguing it needs to be introduced for ethical reasons and to ensure a more effective species protection.This discussion frequently involves cases when hunters break the law,illustrated by photographs published on social media,documenting culling of legally protected species.In response hunters mention the need to verify the sources and the context for published materials.展开更多
文摘This paper investigates a conservator’s approach to a particular subset of physical cultural property:clocks.It looks at established conservation frameworks and practical elements of codes of practice,and considers how the conservator’s perspective will differ from that of a peer engaged solely with an approach to static objects.The paper considers,through examples of historic technological development,how what we mean by"clock"and how we consider clocks are in a state of constant change of context.Clocks are a diverse group of objects,some of which are technically complex.The conservator must draw together many influences in order to demonstrate professional competence in thinking,delivering an accountable decision-making process.In order to illustrate the breadth of the challenge the conservator faces when approaching clocks,the paper gives examples of three contrasting case study objects including one automaton and one electromechanical model.Clocks as a group comprise multimedia and multimedium objects.The perspective of the conservator will draw on professional networks within and without the immediate field,including at times the work of philosophers,scientists,sociologists,and historians in order to maintain objectivity,inform and engender new ideas.The paper concludes with the statement that the perspective of the conservator engaged with clocks should never be fixed,and that solutions to the challenges presented by clocks are never absolute and never permanent,but are in constant context-driven flux.
文摘Aconitum heterophyllum Wall.ex Royle,an endangered Ayurvedic medicinal plant,is predominantly found in the alpine and subalpine zones of the Himalayas.This study aimed to enhance seed germination under various soil conditions,to facilitate conservation and provide opportunities for income generation through large-scale cultivation.The selection of soil treatments was based on their contrasting physicochemical properties and known influence on seed germination in related high altitude species.The study was conducted in a mist chamber at the Deoban nursery in Dehradun,India,using five soil conditions:normal forest soil(NS),vermiculite(Vc),vermiculite+normal forest soil(Vc+NS),normal forest soil+sand(NS+S),and a mixture of soil,sand,vermiculite,and vermicompost(NS+S+Vc+VCo).All the soil treatments were replicated ten times under the controlled environmental conditions.These substrates were selected to represent a gradient of water retention,aeration,nutrient content,and organic matter composition,which are known to affect seed germination and early seedling development.Results showed significant different among treatments in terms of physical and chemical soil properties in sand,silt,clay,pH,organic carbon,organic matter,total nitrogen,total phosphorus,as well as growth parameters such as,seed vigor index,root length,plant length,and leaf number across soil conditions.Among all treatments,vermiculite alone showed the highest germination rate(73.33%),peak germination value(0.719),and seed vigor index(24.02),along with superior growth parameters and the lowest seed mortality index(2.45).These findings in addition to its low seed mortality underscore vermiculite's potential as a suitable growth medium for the ex-situ cultivation of A.heterophyllum offering a promising alternative to wild harvesting while supporting conservation and sustainable use of this valuable Himalayan species.
基金supported by National Key Research and Development Program of China(2024YFF1307400)Hubei Provincial Natural Science Foundation and Three Gorges Innovation Development Joint Fund(Grant No.2023AFD195)China Three Gorges Corporation(NBZZ202300130).
文摘Successful ex situ conservation of plant populations requires a high degree of genetic representativeness.However,spatially biased sampling in ex situ conservation efforts may fail to capture all wild genetic clusters for species with range-wide genetic structure.To investigate the extent of spatially biased sampling in living collections and the coverage of wild genetic clusters in plant populations under ex situ conservation worldwide,we combined a global synthesis of ex situ conservation efforts with a case study of an endangered riparian plant species,Myricaria laxiflora.Our analysis of ex situ conservation worldwide revealed that the majority(82.6%)of ex situ populations fail to cover all wild genetic clusters,largely due to spatially biased sampling with low geographic coverage.Our case study of M.laxiflora showed that genetic diversity differed between the ex situ and upstream populations,while it was comparable between ex situ populations and other wild populations.However,current ex situ populations did not cover all wild genetic clusters,as the upstream genetic cluster was previously uncollected.Our study suggests that the failure to cover all wild genetic clusters in ex situ populations is a widespread issue,and ex situ populations with high genetic diversity can also fail to cover all wild genetic clusters.In future ex situ conservation programs,both the importance of high genetic diversity and the high coverage of wild genetic clusters should be prioritized.
基金part of the project on soil and water management approved and supported by the Department of Agronomy,Nasarawa State University,Keffi(NSUK),Nigeria。
文摘African drylands occupied 19.6 million km~2(46%of the total global area)and 525 million people.Soil erosion models are useful for assessing the impact of soil erosion in the dryland areas.This review provides an assessment of soil erosion/deposition models and soil conservation practices,which are supportive for mitigating the impact of soil erosion and maintaining soil health and soil functional services for food security in African drylands.The theories of soil erosion models and soil conservation practices provide advanced ways to understand the detailed impact of soil erosion and management solutions.The paper reviews a set of useful soil erosion models and traditional conservation practices,which can control soil erosion and enhance dryland farming systems in Africa.Soil erosion models are classified into three categories:empirical,conceptual,and physical.Soil conservation practices include reduced tillage,advanced cover crops,mechanical structures(barriers made of stones/gravel/vegetation),advanced mechanical roller-crimper technique,mixed cropping,intercropping,crop rotation systems,terracing techniques,and land modification techniques.These conservation practices are effective in controlling soil erosion,reducing soil damage,improving soil health and quality,enhancing soil fertility,and ensuring food security.The existing assessment suggests that understanding the theories of soil erosion models and soil conservation practices is a first step towards addressing soil erosion problems in African drylands.
文摘Background:We present a case of two major complications following insertion of a nephrostomy managed in a minimally invasive way.Our case is the first in the literature to describe this minimally invasive treatment technique for colon perforation in a completely asymptomatic patient.Case Description:A 75-year-old female patient with a history of bilateral obstructive uropathy secondary to bilateral radiation-induced ureteric strictures attended for bilateral nephrostomy placement.The patient had a history of endometrial cancer,treated previously by total hysterectomy and bilateral salpingo-oophorectomy with adjuvant chemo-radiotherapy and brachytherapy.Her recovery had been further complicated by the development of radiation cystitis,small bowel resection,and short gut syndrome.The strictures had previously been managed with bilateral double J stents,which have now failed.A left-sided nephrostomy insertion was performed.ACT-scan prompted by a repeat deterioration in renal function revealed a right-sided hydronephrosis and suggested transcolic passage of the previously placed leftsided nephrostomy.She had remained clinically well and apyretic.A right-sided nephrostomy was inserted,and the left re-sited following a colonoscopy-guided nephrostomy removal and clip occlusion of the nephrostomy tract.The patient then developed a pseudoaneurysm,which was managed with embolization.The patient was able to return home with corrected kidney function.The three-monthly checks for changes in nephrostomy catheters did not reveal any complications.Conclusions:The patient therefore presented with two major complications of nephrostomy placement:colonic perforation and pseudoaneurysm,classified as Clavien IIIb and IIIa,respectively.Multidisciplinary management,including urologists,gastroenterologists,general surgeons,and radiologists,enabled a minimally invasive management.Minimally invasive management with endoscopic clip placement appears to be a safe alternative to directed fistula of colonic perforation.
文摘Bhutan is a biodiverse country,yet there are relatively few scientific studies on its herpetofauna.To determine research gaps and opportunities for scientific advances,we completed a literature review on amphibians and reptiles of Bhutanese origin from online databases including ResearchGate,Google Scholar,the Integrated Taxonomic Information System(ITIS),and relevant authors.Of the 63 studies on herpetofauna of Bhutan between 1972 and 2022,most focused on reptiles(45%)followed by amphibians(32%),while fewer(23%)included both taxa.Most studies were field-based(n=44),followed by desktop research(n=14),and then laboratory work(n=5).Ecology and natural history studies(n=35)dominated the literature,while other disciplines included conservation and anthropogenic interactions(n=22),then evolution,taxonomy,and systematics(n=4).Single reports existed on disease,and on genetic studies.After 2009,the quantity of literature rose considerably to a total of 52 publications on Bhutanese herpetofauna.Most studies have been conducted by Bhutanese researchers(n=36),followed by collaborations with scientists from outside the country(n=15),and work published by foreign scientists alone(n=12)contributed some of the earliest studies.There was a bias in the taxa studied,the type of research,and the location of study.Research concentrating on anatomy or physiology was absent,while studies on disease,genetics,taxonomy,and systematic classification are scarce.There is a pressing need for increased conservation-oriented studies,as they were poorly represented.These gaps offer direction for further research.In particular,there are few studies on the diversity and distribution of amphibians and reptiles-such information is key to analysing threats and developing effective conservation strategies.Such knowledge would contribute greatly towards the conservation and management of Bhutan’s native amphibians and reptiles.Bhutan currently harbours ca.83 amphibian species(31 genera,8 families,3 orders:Anura,Caudata,Gymnophiona)and ca.138 reptile species(58 genera,17 families,2 orders:Squamata,Testudines).Bhutan does have crocodiles,but they are in captivity only.
基金supported by Science and Technology Program from the Forestry Administration of Guangdong Province(2024KJQT0012)the Guangdong Provincial Key R&D Program(2022B1111040001)+2 种基金the National Forestry Administration rare and endangered species field rescue and breeding project(Gui lin hu yu O10)the National Natural Science Foundation of China(32200337)a fellowship from the China Postdoctoral Science Foundation(2022M712003).
文摘Gibbons are small,arboreal apes that play a critical role in tropical biodiversity and ecosystem ecology.However,nearly all species of gibbons are threatened by habitat loss,illegal trade,hunting,and other human activities.Long-term poor understanding of their genetics and evolution undermines effective conservation efforts.In this study,we analyse comparative population genomic data of four Nomascus species.Our results reveal strong genetic differentiation and gene flow among Nomascus species.Additionally,we identify genomic features that are potentially related to natural selection linked to vocalization,fructose metabolism,motor balance,and body size,consistent with the unique phenotype and adaptability of gibbons.Inbreeding,coupled with population declines due to climate change and historical human activities,leads to reduced genetic diversity and the accumulation of deleterious variations that likely affect cardiovascular disease and the reproductive potential of gibbons and further reduce their fitness,highlighting the urgent need for effective conservation strategies.
基金supported by the Gaoligong Mountain Ecological Function Enhancement and Sustainable Development Technology Research(202303AC1000120303)Gaoligong Mountain Ecological Function Enhancement and Invasive Plant Species Prevention and Control Technology Project(2022YFF130240304)National Key R&D Program of China(2022YFC2602500)。
文摘Reconciling biodiversity conservation with economic advancement represents a defining challenge of the Anthropocene epoch.Although ecotourism is widely promoted as a strategy capable of delivering both environmental and developmental benefits,empirical evidence regarding its ecological and socioeconomic impacts remains limited.This study critically examined the Hide-in-Bird Pond(HIBP)model,a rapidly expanding,community-based avitourism framework in China that integrates targeted wildlife provisioning with concealed infrastructure for bird observation,simultaneously establishing a novel income source for economically marginalized rural regions through ecotourism.Semi-structured online interviews were conducted with 98 HIBP operators,and thematic analysis was applied to evaluate current developmental patterns,spatial distribution,and conservation outcomes.A total of 251 HIBP sites were identified across China,predominantly located in biodiversity-rich but economically marginalized regions.These sites collectively supported 524 bird species—36%of China's avifauna—including 148 species classified as nationally protected or threatened(38%of nationally listed bird taxa).These findings suggest that HIBP can serve as an integrative socio-ecological platform that aligns conservation objectives with sustainable rural development.However,the absence of standardized governance frameworks and ecological safeguards poses significant risks to biodiversity an d long-term sustainability.Implementation of science-based adaptive management systems,incorporating systematic biodiversity monitoring,inclusive stakeholder coordination,and certified sustainable tourism protocols,is critical to ensure ecological integrity and sectoral resilience.These findings offer novel insights into aligning conservation objectives with economic development across regions characterized by high biodiversity and persistent economic disadvantage.
文摘Lichens exhibit exceptional ecological adaptability,thriving in diverse habitats ranging from temperate forests to extreme environments.They colonize various substrates,including tree bark,rocks,soil,and artificial surfaces,playing critical roles as bioindicators of air quality and environmental change.Despite their ecological and economic importance,regions like Pakistan remain underexplored for lichen diversity,leaving significant gaps in knowledge about local lichen flora.This study hypothesizes that the ecological diversity and environmental gradients in the Hazara Division,Khyber Pakhtunkhwa,significantly influence the distribution,composition,and community structure of lichens.Field surveys were conducted from March 2021 to December 2023 across 48 locations in the Hazara Division,covering diverse altitudes,aspects,and vegetation types.Epiphytic lichens were sampled using standardized transect methods with vertical grids on tree stems.Specimens were collected,shade-dried,and identified using chemical spot tests.Multivariate analyses,including TWINSPAN,CCA,and DCA,were employed to examine species-environment relationships.A total of 97 lichen species were identified across 44 genera and 19 families.Physciaceae was the dominant family(24 species).Foliose lichens represented 55%of the total species,highlighting morphological diversity.Among the recorded species,11 were new to Pakistan,and 30 were newly documented for the Himalayan region of Hazara.The study documented 52 host tree species across 36 genera,with Quercus being the most dominant genus.Multivariate analyses identified seven distinct lichen communities.Altitude and road distance emerged as the strongest drivers of lichen distribution,with specific species exhibiting distinct responses to environmental gradients.In DCA ordination the Eigen value was maximum for axis 1,(0.67)followed by axis 2(0.56).The maximum gradients was 5.87 recorded axis 1.Canonical Correspondence Analysis captured 15.09%of the total variation,with significant contributions from altitude,temperature,and substrate type.The per mutation result for all axis were pseudo(F=1.1,P=0.01).The result showed that species,stand and environmental variables were in linear combination with each other.This study provides the first comprehensive assessment of lichen diversity and ecology in the Hazara Division,unveiling significant species-environment relationships and ecological patterns.The findings underscore the importance of multivariate analysis in lichen studies and highlight the region's potential for further ecological and conservation research.
基金supported by grants from the National Natural Science Foundation of China(Grant No.32360333)the Guizhou Provincial Science and Technology Projects(Grant Nos.ZK[2022]540 and[2023]099)+1 种基金the Survey of Amphibian and Reptile Resources in Leigongshan National Nature Reserve and Literature Publishing Services(P5226002023000019)the Guizhou Provincial Science and Technology Innovation Talent Team Construction Project 2024[Qian Ke He Talent CXTD(2025)053].
文摘Dear Editor,Mountain systems have long been refuges for many species,often viewed as"islands"that promote speciation due to geographic isolation(Rahbek et al.,2019).Their high environmental heterogeneity fosters centers of endemism,and they harbor over 85%of global species diversity(Zhao et al.,2022).Consequently,mountains are key systems for exploring biodiversity patterns along elevational gradients,where species richness often follows four recognized models:monotonic decrease,unimodal pattern(forward and backward peak patterns),and low plateau followed by a decrease along the elevational gradient(McCain et al.,2010).
基金the Chinese Academy of Sciences Research Center for Ecology and Environment of Central Asia(RCEECA),the construction and joint research for the China-Tajikistan“Belt and Road”Joint Laboratory on Biodiversity Conservation and Sustainable Use(2024YFE0214200)the Shanghai Cooperation Organization Partnership and International Technology Cooperation Plan of Science and Technology Projects(2023E01018,2025E01056)the Chinese Academy of Sciences President’s International Fellowship Initiative(PIFI)(2024VBC0006).
文摘Tajikistan represents a core region of the biodiversity hotspot in Central Asian mountains and has exceptional vascular plant diversity.However,the species diversity of the country faces urgent conservation challenges.There has been a lack of a comprehensive and multidimensional assessment to inform strategic conservation planning.Therefore,this study integrated 4 key biodiversity indices including species richness(SR),phylogenetic diversity(PD),threatened species richness(TSR),and endemic species richness(ESR)to map species diversity distribution patterns,identify conservation gaps,and elucidate their effects of climatic factors.This study revealed that species diversity shows a clear trend of decreasing from the western region to the eastern region of Tajikistan.The central–western mountains(specifically the Gissar-Darvasian and Zeravshanian regions)emerge as irreplaceable biodiversity hotspots.However,we found a severe spatial mismatch between these priority areas and the existing protected areas(PAs).Protection coverage for all hotspots was alarmingly low,ranging from 31.00%to 38.00%.Consequently,a critical 64.80%of integrated priority areas fall outside of the current PAs,representing a major conservation gap.This study identified precipitation seasonality and isothermality as the principal drivers,collectively explaining over 50.00%of the diversity variation and suggesting high vulnerability to hydrological shifts.Furthermore,we detected significant geographic sampling bias in the public biodiversity databases,with the most critical hotspot being systematically under-sampled.This study provides a robust scientific basis for conservation action,highlighting the urgent need to strategically expand PAs in the under-protected southwestern region and to mitigate critical sampling gaps through targeted data digitization and field surveys.These measures are indispensable for securing Tajikistan’s unique biodiversity and achieving the Kunming-Montreal Global Biodiversity Framework Target 3(“30×30 Protection”).
文摘Sikkim,located in the Eastern Himalayan Region,represents one of the 36 globally recognized biodiversity hotspots and harbors an exceptional range of ecosystems within a relatively small geographic area.Over the past few decades,the region has witnessed rapid urbanization alongside other developmental activities such as hydropower construction,road expansion,mining and infrastructure development.While these processes have contributed to socioeconomic development,they have simultaneously exerted significant pressure on the fragile mountain environment.This review examines the impacts of urbanization on biodiversity in the Sikkim Himalaya drawing attention to the ways in which land-use change due to urbanization,habitat fragmentation and economic development have altered ecological dynamics and threatened biodiversity of this region.The findings of the current study suggest that unplanned urban growth has led to the degradation of forest cover,disruption of ecological corridors thereby diminishing ecosystem resilience of the region.In addition,the current study highlights the challenges of balancing developmental imperatives with environmental conservation in the study area where both ecological integrity and human livelihoods are intricately interdependent.This study highlights the urgent need for integrated land-use planning that incorporates ecological corridors,urban green spaces,and community-based conservation to mitigate biodiversity loss.Strengthened governance, sustainable tourism, invasive species control, and systematic biodiversity monitoring are essential tobalance urban development with ecological integrity. Most importantly, holistic and interdisciplinary approaches arecritical to ensuring that urban growth in the Global Biodiversity Hotspot of the Sikkim Himalaya aligns with globalbiodiversity conservation goals and the Sustainable Development Goals (SDGs).
基金sponsored by the National Natural Science Foundation of China(Nos.12235007,11975131)。
文摘This paper presents a geometric perspective that connects reciprocal transformations with multidimensional integrable deformations.By interpreting conservation laws as closed 1-forms,we formalize reciprocal transformations as induced local diffeomorphisms on the jet bundle.This allows us to characterize higher-dimensional deformations as systematic fiber bundle extensions,where fiber coordinates are generated by potential functions of the conservation laws.This perspective provides an interpretation for the covariant lifting of Lax pairs to higher dimensions and reveals that auto-Backlund transformations are composite diffeomorphisms.These results are applied to several classical integrable models.
基金supported by the National Key Research and Development Project[Grand No.2022YFF0802304]Key Research and Development and Transformation Project of the Xizang Autonomous Region[Grand No.XZ202501ZY0119].
文摘It is essential to understand how adaptation needs and options differ among stakeholders in protected areas(PAs)to effectively implement climate change(CC)adaptation strategies.Using the Qiangtang PA in Xizang as a case study,this research examines CC adaptation needs and options from the perspectives of stakeholders across multiple administrative levels,including provincial,prefectural,county authorities,73 protection stations,and 13364 pastoralists residing within the PA.The findings show that stakeholders at the provincial level,as well as those from the Ali and Naqu prefectures and six counties,place greater emphasis on institutional and resource-related needs than on other categories(attention score:7.0-9.3 vs.5.0-7.0).In contrast,stakeholders from the 73 protection stations prioritize technological and capacity-building needs more strongly than other types(attention score:8.0-9.0 vs.4.0-8.0).The 13364 pastoralists assign the highest importance to social needs relative to other categories(attention score:9.0-9.5 vs.3.0-8.0).Most of the eight existing protection measures were found to indirectly support broader climate adaptation efforts.In particular,protective actions addressing fire,pests,and weather-related disasters can be classified as autonomous adaptation,while other measures generate outcomes that enhance adaptation capacity under specific conditions.Adaptation options,grouped into three main types and 13 subcategories,differ across stakeholder groups,although substantial overlap exists between these options and current protective actions,including ecosystem based adaptation strategies,adaptation-related practices,autonomous adaptation measures,and emergency interventions.Overall,these findings highlight the critical role of all stakeholders-especially staff from the 73 protection stations and the 13364 pastoralists-in the effective implementation of adaptation actions within the PA.
基金support of the ORG.one project of Oxford Nanopore Technologies(ONT),the Rufford Grants(45249-1)the Idea Wild Grants(Project ID-KJOSINDI0125-00)the Mohamed Bin Zyed Species Conservation(MBZ)(GEF Grant no-240535253)Funds in our efforts to conserve threatened trees in the Western Ghats Biodiversity Hotspot Forest regions.
文摘Plants constitute nearly 80%of the planet’s total biomass(Bar-On et al.,2018);however,this vital group is experiencing severe threats,and recent evaluations indicate that approximately 45%of the world's described plant species are at risk of extinction(Bachman et al.,2024).The number of plant extinctions has increased by 60%in the last 100 years(Di Marco et al.,2017).Over the past 250 years,571 plant species have gone extinct—more than twice the combined total of extinct birds,mammals,and amphibians(217 species)(Briggs,2019).
基金The Science and Technology Basic Resources Survey Project,No.2021FY101002Wetland Protection and Restoration in China Funded by the Palson Institute and Laoniu Foundation,UNDP-GEF Flyway Project,No.PIMS ID:6110。
文摘Effective conservation relies on robust assessments;however,the lack of waterbird data in the Yellow River Basin(YRB)has led to an underestimation of key habitat significance.This study addressed this gap by evaluating YRB wetland conservation importance using waterbirds as indicators and applying Ramsar,Important Bird Areas(IBA),and East Asian-Australasian Flyway(EAAF)criteria.We integrated coordinated surveys with citizen science data,creating a framework that tackles data deficiencies along the under-monitored Central Asian Flyway(CAF).Our analysis identified 75 priority wetlands,supporting 15 threatened species and 49 exceeding global/flyway 1%thresholds,highlighting the basin's biodiversity.We observed strong seasonal habitat use,with high-altitude wetlands vital for breeding and migration,and the Yellow River Delta providing year-round refuge.This research also provided data to refine Baer's Pochard population estimates.Alarmingly,one-third of the identified priority areas,primarily rivers and lakes,remain unprotected.To address this,we recommend systematic surveys,enhanced protected areas,OECMs,and targeted wetland restoration.This study underscores the YRB's role in regional conservation and provides essential data for adaptive management,particularly emphasizing the CAF's importance.
基金supported by the National Natural Science Foundation of China(32300512)and the Xplorer Prize.
文摘Root nodule symbiosis(RNS)is a mutualistic association formed between nitrogen-fixing rhizobia or Frankia and host plants limited to four orders within Rosid I―Fabales,Fagales,Cucurbitales,and Rosales―which comprise the so-called‘Nitrogen Fixing Nodulation Clade’(NFNC).The majority of nodulation studies have focused on Leguminosae,given their agricultural and environmental importance,as well as the widespread occurrence of nodulation among members of this family.Endowing cereal crops with nitrogen fixation,like Leguminosae,presents a strategy to reduce the detrimental effects of synthetic fertilizer overuse.Different hypotheses on the origin of RNS have been proposed;however,key genetic innovations underlying the evolution of RNS,even in Leguminosae,have been rarely reported.In this review,we begin by examining current knowledge of genetic innovations―including gene gain,gene loss,and the acquisition or loss of conserved noncoding sequences(CNS)in preexisting genes.We explore the available evidence supporting these genetic innovations underlying the evolution of RNS in Leguminosae and offer the phylogenomics approach that could be applied to uncover these genetic innovations.Finally,we conclude by proposing a model of genetic innovations underlying the evolution of RNS in Leguminosae and consider the potential implications for the development of nitrogen-fixing crops.
基金supported by the National Natural Science Foundation of China (Grant Nos. 12234002, 92250303, 12474486, 12504301, and 12504396)the National Key Research and Development Program of China (Grant No. 2024YFA1612101)。
文摘With their intricate vectorial structures in space,optical skyrmions have significantly expanded the landscape of topological optics and light-matter interactions.We theoretically investigate high harmonic generation in crystals driven by optical skyrmions.We find that although the skyrmion number is not conserved,the resulting high-order harmonics can exhibit a distinctive multi-vortex structure,whose features are shaped by both the topology of the optical skyrmions and the rotational symmetry of the crystal.The position of the vortex centers can be effectively tuned by employing different types of optical skyrmions.To elucidate the underlying physics,we develop a multi-absorption channel model based on the conservation laws of spin and orbital angular momentum.Our work explores the role of optical topology in extreme nonlinear light-matter interactions,offering new opportunities for the formation and manipulation of optical vortices and novel structured light fields in the visible and ultraviolet regimes.
文摘In recent years bird hunting has become a topical issue in public debate in Poland.Some organizations and communities actively engaged in nature conservation efforts propose a complete ban on hunting,arguing it needs to be introduced for ethical reasons and to ensure a more effective species protection.This discussion frequently involves cases when hunters break the law,illustrated by photographs published on social media,documenting culling of legally protected species.In response hunters mention the need to verify the sources and the context for published materials.
