Stochastic Model of Dengue: Analysing the Probability of Extinction and LLN

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.

A Speculation: Avian Migration and the K-T Extinction

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.

Chinese pangolins (Manis pentadactyla) are not functionally extinct in China

DEAR EDITOR,The key features of functional extinction include continuous reproductive failure,lack of new recruitment,and persistent population decline(Jarićet al.,2016;Roberts et al.,2017).However,the conclusion of functional extinction for the Chinese pangolin(Manis pentadactyla)by the China Biodiversity Conservation and Green Development Foundation(CBC-GDF)based on preliminary field information is unconvincing as they did not assess reproductive function or new individual recruitment of Chinese pangolin populations(Supplementary Materials).

An Improved Pair Method to Probe the Dust Extinction Law

Dust extinction law is crucial to recover the intrinsic energy distribution of celestial objects and infer the characteristics of interstellar dust.Based on the traditional pair method,an improved pair method is proposed to model the dust extinguished spectral energy distribution(SED)of an individual star.Instead of the mathematically parameterizing extinction curves,the extinction curves in this work are directly from the silicate-graphite dust model,so that the dust extinction law can be obtained and the dust properties can be analyzed simultaneously.The ATLAS9 stellar model atmosphere is adopted for the intrinsic SEDs in this work,while the silicate-graphite dust model with a dust size distribution of dn da~a^(-a)exp(-a a_(c)),0.005<a<5μmfor each component is adopted for the model extinction curves.One typical extinction tracer in the dense region(V410 Anon9)and one in the diffuse region(Cyg OB2#12)of the Milky Way are chosen to test the reliability and the practicability of the improved pair method in different stellar environments.The results are consistent with their interstellar environments and are in agreement with the previous observations and studies,which prove that the improved pair method is effective and applicable in different stellar environments.In addition to the reliable extinction results,the derived parameters in the dust model can be used to analyze the dust properties,which cannot be achieved by other methods with the mathematical extinction models.With the improved pair method,the stellar parameters can also be inferred and the extinction law beyond the wavelengths of observed data can be predicted based on the dust model as well.

Dynamic Variation and Simulation of Extinction Coefficient of Corn Population

[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.

Reconstructed Light Extinction Coefficients Using Chemical Compositions of PM_(2.5) in Winter in Urban Guangzhou, China

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.

Analysis of the Aerosol Extinction Characteristics in Different Areas of China

The multi-wavelength aerosol optical depths and the Angstrom exponent between 450 nm and 900 nm in four locations of China (Miyun, Beijing; Xinfeng, Guangdong; Waliguan, Qinghai and Damxung, Tibet) have been observed by sun-photometers. This paper analyzes their characteristics for a one-year period from February 1998 to January 1999. The results show that in the arid and semi-arid locations like Miyun (117.12°E, 40.65°N) and Waliguan (100.90°E, 36.29°N), there is a maximum of aerosol optical depth in the spring, it is about twice as large as in any other season. In a humid region like Xinfeng (114.2“E, 24.5°N), the aerosol optical depth also has a maximum in the spring, however it is only slightly larger than in other seasons. The Angstrom exponent shows a significant minimum at Waliguan in spring, about 0.15, indicating relatively large dust aerosol particles. Large variability of the monthly mean Angstrom exponent is also found in Miyun and Xinfeng, but there is no tendency with seasons. It means that the source of aerosol in these locations is complicated.

Determination of aerosol extinction coefficient and mass extinction efficiency by DOAS with a flashlight source

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.

Vertical profile of aerosol extinction based on the measurement of O4 of multi-elevation angles with MAX-DOAS

A method for aerosol extinction profile retrieval using ground-based multi-axis differential optical absorption spectroscopy(MAX-DOAS)is studied,which is based on a look-up table algorithm.The algorithm uses parametric method to represent aerosol extinction profiles and simulate different atmospheric aerosol states through atmospheric radiation transfer model.Based on the method,aerosol extinction profile was obtained during six cloud-free days.The O4 differential air mass factor(dAMF)measured by MAX-DOAS is compared with the corresponding model results under different atmospheric conditions(R^2=0.78).The aerosol optical thickness,aerosol weight factor in boundary layer,and the height of the boundary layer are obtained after the process of minimization and look-up table method.The retrieved aerosol extinction in boundary layer is compared with PM2.5 data measured by ground point instrument.The diurnal variation trends of the two methods are in good agreement.The correlation coefficients of the two methods are 0.71 when the aerosol optical thickness is smaller than 0.5.The results show that the look-up table method can obtain the aerosol state of the troposphere and provide validation for other instrument data.

Climate change challenge, extinction risk, and successful conservation experiences for a threatened primate species in China: Golden snub-nosed monkey(Rhinopithecus roxellana)

DEAR EDITOR, Despite the vulnerability of primates to the negative impacts of human activities and climate change, there is still room for optimism. Notably, years of conservation efforts may have paid off for the golden snub-nosed monkey(Rhinopithecus roxellana). Our field surveys confirmed the existence of 188 to 220 wild multilevel societies(MLS) of R. roxellana, with an estimated 22 710 to 26 130 individuals in 2019。

Analysis of influence of atmosphere extinction to Raman lidar monitoring CO2 concentration profile

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.

Stratigraphical Time——Correlation and Mass Extinction Event Near Permian——Triassic Boundary in South China

Shaw's method used to correlate 40 sections across the Permo-Triassic boundary in South China is applied in the paper. Two steps are adopted to get an Integral Composite Section (ICS) by synthesizing these data : First , South China is divided into five areas and composite section developed for each area . Then the second step . the Changxing composite section is regarded as a composite standard (CSRS) while the ICS is produced by matching the CSRS with composite sections of the other areas. Three biozones in the Changxingian and two biozones in the Griesbachian can be discerned on the basis of computing Z values in the ICS. These biozones are marked by the Z values which quantitatively represent their time ranges ; therefore , they may increase accuracy of stratigraphic time correlation . The mass extinction at the end of the Permian is an abrupt event that is supported by the relative rate of extinction near the P/T boundary . About 90% of invertebrate species died out by the end of the Permian . The duration of the mass extinction is rather short ,approximately 0.018Ma .

Dependence of Mixed Aerosol Light Scattering Extinction on Relative Humidity in Beijing and Hong Kong

The hygroscopic properties of mixed aerosol particles are crucial for the application of remote sensing products of aerosol optical parameters in the study of air quality and climate at multiple scales. In this study, the authors investigated aerosol optical properties as a func tion of relative humidity （RH） for two representative me tropolises： Beijing and Hong Kong. In addition to the RH data, mass concentrations of PM10 （particulate matter up to 10 utm in diameter） and aerosol scattering extinction coefficient （aext） data were used. The relationship between the mass scattering extinction efficiency （MEE, defined as O＇ext/PMl0） and RH can be expressed by regression func tions asf= 1.52x ＋ 0.29 （re= 0.77）,f= 1.42x ＋ 1.53 （re= 0.58）,f= 1.19x ＋ 0.65 （re= 0.59）, andf= 1.58x ＋ 1.30 （re = 0.61） for spring, summer, autumn, and winter, respec tively, in Beijing. Here, f represents MEE, x represents I/（1-RH）, and the coefficients of determination are pre sented in parentheses. Conversely, in Hong Kong, the corresponding functions are f= 1.98x- 1.40 （r^2= 0.55）,f = 1.32x - 0.36 （r^2 = 0.26）,f= 1.87x - 0.65 （r^2 = 0.64）, and f= 2.39x - 1.47 （r^2 = 0.72）, respectively. The MEE values for Hong Kong at high RHs （RH 〉 70%） are higher than those for Beijing, except in summer; this suggests that aerosols in Hong Kong are more hygroscopic than those in Beijing for the other three seasons, but the aerosol hy groscopicity is similarly high in summer over both cities. This study describes the effects of moisture on aerosol scattering extinction coefficients and provides a potential method of studying atmospheric visibility and ground level air quality using some of the optical remote sensing products of satellites.

Simultaneous low extinction and high local field enhancement in Ag nanocubes

We theoretically investigate surface plasmon resonance properties in Au and Ag cubic nanoparticles and find a novel plasmonic mode that exhibits simultaneous low extinction and high local field enhancement properties. We analyse this mode from different aspects by looking at the distribution patterns of local field intensity, energy flux, absorption and charge density. We find that in the mode the polarized charge is highly densified in a very limited volume around the corner of the nanocube and results in very strong local field enhancement. Perturbations of the incident energy flux and light absorption are also strongly localized in this small volume of the corner region, leading to both low absorption and low scattering cross section. As a result, the extinction is low for the mode. Metal nanoparticles involving such peculiar modes may be useful for constructing nonlinear compound materials with low linear absorption and high nonlinearity.

Combination Features,Paleobiogeographic Affinity and Mass Extinction of the Latest Ordovician(Hirnantian) Rugosan Fauna from Northern Guizhou,China

The rugosan fauna from the Guanyinqiao Bed （latest Ordovician, Hirnantian） of northern Guizhou, China is known to belong to the cold or cool-water type corals. The components of the fauna are solitary corals only, and corallite septa are generally strongly dilated, especially the streptelasmatid corals are dominant comprising 98% of the whole fauna. The Guanyinqiao Bed is rich in rugosans of 18 genera, which are streptelasnmtid Streptelasma （=Helicelasma）, Brachyelasma, Amplexobrachyelasma, Salvadorea, Grewingkia, Borelasma, CrassUasma, Leolasma, KenophyUum, UUernelasma, Paramplexoides, Siphonolasma, Pycnactoides, Dalmanophyllum, Bodophyllum, Axiphoria, Lambeophyllum and cystiphyllid Sinkiangolasma. Although this fauna was fairly abundant in a confined area （northern-northeastern Guizhou, southern Sichuan） during the Hirnantian age, the rugosan mass extinction （generic extinction rate 81%） happened at the end of the Hirnantian Stage. It is conduded that the mass extinction is related to the ending of maximum glaciation and ice cap melting in Gondwana in the southern hemisphere in the latest Hirnantian, resulting in rapid global sea-level rise in the earliest Silurian. In the Upper Yangtze Basin, the sea bottom environments were replaced by anoxic and warmer water during that time, so that the cool-water type rugosan became extinct. The present paper attempts to revise some already described rugose coral genera and species （He, 1978, 1985） and to supplement a few new forms from the Guanyinqiao Bed. Fourteen species of 12 genera are re-described and illustrated, of which one species- Grewingkia latifossulata is new. As a whole, the rugosan fauna of the Guanyinqiao Bed may be correlated with those contemporaneous of North Europe, Estonia and North America, indicating a dose biogeographic affinity to North Europe.

New Evidence from Alashan Area of West Nei Monggol to Reveal Enigma of Dinosaur Extinction

Dinosaur extinction of the late Cretaceous is an enigma. A scorched earth layer was discovered at the end of the Cretaceous system from drilling cores in west of Nei Monggol in China. And there was a creature interruption for 6-8 million years after that period through fossil analysis of the area and the adjacent area. Just in the same system of scorched earth layer, the Polish scientists found the abnormal geo chemical phenomena and high dense universal substances generally contained in meteorite. The authors think, at the end of Cretaceous, many celestial bodies ran into the earth. The collision caused fires all over the world and slowed down the speed of the earth rotation suddenly. The oxygen density decreased sharply. And because of the sudden increase of day length, the biological clock of dinosaur was in the state of chaos. That’s the reason why dinosaurs got extinct. It took a very long time both for the oxygen to return normal for most creatures to live and for the new species fit for new rotation speed of the earth to come into being. That’s why there was the creature interruption after the extinction of the dinosaur.

ON THE EXTINCTION OF POPULATION-SIZE-DEPENDENT BISEXUAL GALTON-WATSON PROCESSES

In this article, the population-size-dependent bisexual Galton-Watson processes are considered. Under some suitable conditions on the mating functions and the offspring distribution, existence of the limit of mean growth rate per mating unit is proved. And based on the limit, a criterion to identify whether the process admits ultimate extinct with probability one is obtained.

Volcanism at the Permian-Triassic Boundary in South China and Its Effects on Mass Extinction

This paper discusses the clayrocks widespread at the Permian-Triassic boundary, which are mostly of volcanic origin. Volcanogenetic textures, structures and minerals such as high-temperature quartz are found in clayrocks at the Permian-Triassic boundary in many places. Thousands of microspherules have been collected from the Boundary clayrocks, many of which exhibit the typical features of the process from melting to cooling and solidification. indicating that they were formed by volcanic eruption or extraterrestrial impact. Volcanic effects on the Permian-Triassic mass extinction may be reflected in conodonts, algae and ammonoids. The Boundary clayrocks are found in many Permian-Triassic sections along the coast of Tethys. Their orighin remains to be studied.

A New View of the Mass Extinctions and the Worldwide Floods

In this study, the reasons for mass extinction in Jurassic were investigated. It was shown that galactic compression led to the activation of terrestrial nuclear reactors, which in turn led to the changes in tectonic activity, volcano eruptions, LIPs, MORBs, paleoclimate change, drift of continents, narrowing of the Earth, worldwide floods, tsunami, changes in mantle and core structures, in magnetic fields and in sedimentary isotopes. It was shown that the mass extinctions occurred during worldwide floods, caused by the narrowing of the Earth at the time of galactic gravitational compression. It was shown that the average statistical altitude distribution of dinosaurs has a bimodal distribution and corresponds to permanent migrations between the plains and the hills. It has been suggested that the skeletons of dinosaurs are well preserved as a result of covering the bodies of dinosaurs with mud flows of coastal sediments and the soil layers at worldwide tsunami. It was formulated the requirement to paleontology, consisting in the obligatory registration of altitudes of the actual place of the fossils found. The simple explanation of the presence of boundaries in the structure of the Earth is given: the 40K nuclear layer corresponds to the boundary between upper and lower mantle;the 137Cs layer located on the boundary between the lower mantle and the outer core;the Th-U nuclear layer is a border between outer and inner core. The previously abstract theories of subduction and continents drift have a clear and obvious physical sense. It was shown that the standard geological table is a registration book of galactic events during Paleozoic. It is proposed to restore the structure of the galactic arms by the geological deposits on the Earth. It was suggested to create the stations on elevated hills for rescue and regeneration of biological forms in the future.

An Empirical Method for Estimating Background Stratospheric Aerosol Extinction Profiles over China

The current paper introduces an empirical method for estimating the vertical distribution of background stratospheric aerosol extinction profiles covering the latitude bands of 50±5°N,40±5°N,30±5°N,and 20±5°N and the longitude range of 75 135°E based on Stratospheric Aerosol and Gas Experiment (SAGE) II aerosol extinction measurements at wavelengths of 1020 nm,525 nm,452 nm,and 386 nm for the volcanically calm years between 1998 2004.With this method,the vertical distribution of stratospheric aerosol extinction coefficients can be estimated according to latitude and wavelength.Comparisons of the empirically calculated aerosol extinction profiles and the SAGE II aerosol measurements show that the empirically calculated aerosol extinction coefficients are consistent with SAGE II values,with relative differences within 10% from 2 km above the tropopause to 33 km,and within 22% from 33 km to 35 km.The empirically calculated aerosol stratospheric optical depths (vertically integrated aerosol extinction coefficient) at the four wavelengths are also consistent with the corresponding SAGE II optical depth measurements,with differences within 2.2% in the altitude range from 2 km above the tropopause to 35 km.