Centroid Shift Research Articles

An Analysis and Optimization of Distortion Effect Caused by Pupil Decentering in Optical Gun Scope

During the use of optical gun scopes, slight movements between the human eye and the instrument can cause the pupil to offset from the optical axis, resulting in a dynamic distortion effect. This affects the accuracy and stability of aiming. Based on the mechanism, this study established parameters of the centroid’s deviation of image spots for marginal field points under pupil decentering and centering conditions and their differences to quantitatively evaluate the distortion. These evaluation parameters were obtained by performing a double integral calculation of the ray aberration distribution function over the entire designed exit pupil. Based on this evaluation method, three optical design strategies for reducing the distortion were proposed: optimizing ray aberrations, optimizing centroid shift of image spots, and utilizing vignetting effects. An optimization process was established by combining increasing vignetting and suppressing centroid shift. For a gun scope with significant distortion, the distortion effect was significantly weakened by increasing the vignetting factor and optimizing the centroid shift of image spots. This proved the effectiveness of the proposed analysis, evaluation, and optimization design methods.

An Analysis of the Spatiotemporal Distribution and Influencing Factors of National Intangible Cultural Heritage along the Grand Canal of China

Intangible cultural heritage (ICH) reflects a region’s history and culture, serving as a significant indicator of regional identity and cohesion. The Grand Canal Basin in China is rich in historical traditions, containing a rich array of ICH resources. Analyzing the spatiotemporal distribution characteristics and influencing factors of ICH within the Grand Canal Basin of China can provide a scientific basis for developing cultural industries and promoting sustainable regional economic growth. This study employed GIS-based spatial analysis methods, including kernel density estimation, the mean nearest neighbor index, and standard deviation ellipse, to investigate the spatiotemporal distribution of 504 national-level ICH items (including extensions) in the Grand Canal Basin of China. The results demonstrate the significant spatial clustering of ICH, with concentrations in high-density regions, particularly at the northern and southern ends of the canal. There is significant regional disparity in the distribution of ICH, with an uneven quantity and structure, predominantly featuring traditional skills and traditional drama categories. The average centroid shift of ICH exhibits a north-to-south oscillatory trajectory. However, overall, it demonstrates a southward-moving trend. This study also underscores the impacts of urbanization, population density, economic development, and transportation infrastructure on ICH distribution. Among these factors, urbanization exerts the strongest influence on the spatial distribution of ICH. The impact of the natural environment is relatively minor; however, it remains a significant element that cannot be overlooked during development. This research offers valuable data and insights for local governments and institutions to formulate evidence-based strategies for the protection and sustainable utilization of ICH resources, promoting sustainable cultural and economic development in the Grand Canal Basin.

New Buckling Curve for a Compressed Member with Cold-Formed Channel Cross-Section

The verification of a column made from a lipped cold-formed channel section, subjected to pure axial compression relative to the gross cross-section, often results in a combined verification of bending and compression due to the appearance of a shift of the centroid of its effective cross-section. Following Eurocode 3 rules, this requires the determination of two distinct effective cross-sections and various interaction factors. This paper, based on an analytic approach, offers a modification to the actual buckling curve, based on Ayrton–Perry formulation, to include the second-order effects raised by the eventual shift of the effective centroid due to local buckling of the compressed web plate. This eliminates the need to use an interaction formula. The modified buckling curve is verified based on a GMNIA analysis performed on a numerical parametric model, which was previously validated by laboratory tests. In addition, the results are compared with strength results provided by appropriate Eurocode 3 formulas and AISI Direct Strength Method for global-local interaction and with classic experimental results.

Super‐Sensitive Multi‐Modal Optical Manometer Based on Huge Pressure‐Induced Spectral Red‐Shift and Broadening of Mn2+ Emission Band in Green‐Emitting Zn2GeO4 Phosphors

AbstractTo overcome the small sensitivities of luminescent manometers, Mn2+‐activated Zn2GeO4 green‐emitting phosphors with admirable manometric characteristics are synthesized. The structural stability of the studied samples is theoretically and experimentally investigated. Moreover, as pressure elevates, a huge spectral red‐shift and a broadening of the emission band are observed in studied samples, contributing to color‐tunable luminescence, i.e., from green to yellow, and ultimately to orange–red. Specifically, when pressure increases to 6.76 GPa, the emission band centroid shifts from 535.9 to 634.9 nm, leading to a superior sensitivity of dλ/dp = 21.3 nm/GPa. Whereas, in the same operating pressure range, the full width at half maximum (FWHM) of the emission band rises from 32.3 to 102.9 nm, resulting in unprecedentedly high sensitivity of dFWHM/dp = 17.0 nm/GPa. Furthermore, through analyzing the pressure‐dependent color coordinates, a maximum sensitivity of 29.43% GPa−1 is achieved, when x‐coordinate is adopted. Additionally, the applicability of the developed manometer is confirmed by a simple uniaxial pressure experiments to showcase its practical use in industrial and daily‐life purposes. Notably, the designed sensor exhibits the highest pressure sensitivities reported to date in different modes, namely, emission band centroid, FWHM and color coordinate, making supersensitive multimodal optical manometry a reality.

Prediction of Forest-Fire Occurrence in Eastern China Utilizing Deep Learning and Spatial Analysis

Forest fires are a major natural calamity that inflict substantial harm on forest resources and the socio-economic landscape. The eastern region of China is particularly susceptible to frequent forest fires, characterized by high population density and vibrant economic activities. Precise forecasting in this area is essential for devising effective prevention strategies. This research utilizes a blend of kernel density analysis, autocorrelation analysis, and the standard deviation ellipse method, augmented by geographic information systems (GISs) and deep-learning techniques, to develop an accurate prediction system for forest-fire occurrences. The deep-learning model incorporates data on meteorological conditions, topography, vegetation, infrastructure, and socio-cultural factors to produce monthly forecasts and assessments. This approach enables the identification of spatial patterns and temporal trends in fire occurrences, enhancing both the precision and breadth of the predictions. The results show that global and local autocorrelation analyses reveal high-incidence areas mainly concentrated in Guangdong, Fujian, and Zhejiang provinces, with cities like Jiangmen exhibiting distinct concentration characteristics and a varied spatial distribution of fire occurrences. Kernel density analysis further pinpoints high-density fire zones primarily in Meizhou, Qingyuan, and Jiangmen in Guangdong Province, and Dongfang City in Hainan Province. Standard deviation ellipse and centroid shift analysis indicate a significant northward shift in the fire-occurrence centroid over the past 20 years, with an expanding spatial distribution range, decreasing flattening, and relatively stable fire-occurrence direction. The model performs effectively on the validation set, achieving an accuracy of 80.6%, an F1 score of 81.6%, and an AUC of 88.2%, demonstrating its practical applicability. Moreover, monthly fire zoning analysis reveals that high-incidence areas in spring and winter are mainly concentrated in Guangdong, Fujian, Zhejiang, and Hainan, while autumn shows widespread medium-incidence areas, and summer presents lower fire occurrences in most regions. These findings illustrate the influence of seasonal climate variations on fire occurrences and highlight the necessity for enhanced fire monitoring and prevention measures tailored to different seasons.

Predicting the potential habitat suitability of Saussurea species in China under future climate scenarios using the optimized Maximum Entropy (MaxEnt) model

The Saussurea species, renowned for its biodiversity and medicinal significance in high-elevation regions, faces endangerment due to climate change and human activities. Despite this, conservation research on Saussurea has been limited. To fill the knowledge gap, this study employed the optimized MaxEnt model to simulate Saussurea's habitat suitability and analyze key environmental factors influencing its distribution. Additionally, considering the sensitivity of Saussurea habitats to climate change, this research also simulated the changes in suitable habitat and distribution centroid shifts of Saussurea under different climate scenarios (SSP126, SSP245, SSP370, and SSP585) for the periods 2040s, 2060s, 2080s and 2100s. Findings indicated that Saussurea's suitable habitat was primarily located in the Qinghai-Tibet Plateau, notably within the Himalayas and Hengduan Mountains. The areas of extremely and moderately suitable habitats were 1.106 × 10⁵ km2 and 3.436 × 10⁵ km2, respectively. Elevation, Isothermality (Bio3), and Temperature Annual Range (Bio7) were identified as the main environmental factors. Future projections suggest severe habitat fragmentation and a decrease in suitable habitat areas. By 2100, the total area of suitable Saussurea habitat will decrease under the SSP126, SSP245, SSP370, and SSP585 scenarios to 8.658 × 10⁵ km2, 6.971 × 10⁵ km2, 5.811 × 10⁵ km2, and 5.979 × 10⁵ km2, respectively. Additionally, a slight southeastward shift in the distribution centroid was observed. This study is expected to provide guidance for the conservation of Saussurea and alpine plant biodiversity.

Feasibility of augmented reality combine patient-specific implants (PSI) applied to navigation in mandibular genioplasty: A phantom experiment

Purpose: Genitoplasty is becoming more and more common, and it is important to improve the accuracy of the procedure and simplify the procedure. This experiment explores the feasibility of using augmented reality (AR) technology combined with PSI titanium plates for navigational assistance in genioplasty performed on models, aiming to study the precision of such surgical interventions.Methods: Twelve genioplasty procedures were designed and implemented on 3D-printed resin mandibular models by the same surgeon using three different approaches: AR+3DT group (AR+PSI) , 3DT group (patient-specific titanium plate) , and a traditional free-hand group(FH group). Postoperative models were assessed using CBCT to evaluate surgical accuracy.Results: In terms of osteotomy accuracy, the AR group demonstrated a surgical error of 0.9440±0.5441 mm, significantly lower than the control group, which had an error of 1.685±0.8907 mm (P < 0.0001). In experiments positioning the distal segment of the chin, the overall centroid shift in the AR group was 0.3661±0.1360 mm, significantly less than the 2.304±0.9629 mm in the 3DT group and 1.562±0.9799 mm in the FH group (P < 0.0001). Regarding angular error, the AR+3DT group showed 2.825±1.373°, significantly <8.283±3.640° in the 3DT group and 7.234±5.241° in the FH group.Conclusion: AR navigation technology combined with PSI titanium plates demonstrates higher surgical accuracy compared to traditional methods and shows feasibility for use. Further validation through clinical trials is necessary.

A cross-fusion of non-local attention network for infrared small target tracking

Infrared small target tracking plays important roles in many applications, such as infrared surveillance and reconnaissance. However, achieving promising performance with existing trackers is difficult due to the following challenges: (1) Infrared small targets lack color and texture information, making it difficult for the network to capture effective features; (2) A slight centroid-shift of the target can lead to tracking failure. To overcome these challenges, this paper proposes the CFNLA network, which consists of two parts: (1) The cross-fusion module is designed to capture the relationship between the target and its surroundings, including a non-local block to enhance the feature information of the target at the current scale and reduce interference such as background; (2) The confidence loss function is proposed to improve tracking stability by forcing the network to concentrate on centroid shift. Furthermore, a self-designed infrared small target tracking dataset, IRSTT, is constructed to evaluate the proposed algorithm. Finally, the experimental results on various open-source datasets and the IRSTT dataset verify the superior performance of the CFNLA network.

Future Range Expansions of Invasive Wasps Suggest Their Increasing Impacts on Global Apiculture.

Until now, no study has examined the future range dynamics of major invasive wasp species to assess their future impacts on global apiculture. Here, we developed 12 species distribution models to calibrate the future range dynamics of 12 major invasive Vespidae wasp species under a unified framework. An increase in their habitat suitability was identified in more than 75% of global land. Substantial range expansions were detected for all 12 species, and they were primarily induced by future climate changes. Notably, Polistes dominula and Vespa crabro had the largest potential ranges under all scenarios, suggesting their greater impact on global apiculture. Polistes chinensis and Vespa velutina nigrithorax had the highest range expansion ratios, so they warrant more urgent attention than the other species. Polistes versicolor and P. chinensis are expected to exhibit the largest centroid shifts, suggesting that substantial shifts in prioritizing regions against their invasions should be made. Europe and the eastern part of the USA were future invasion hotspots for all major invasive wasp species, suggesting that apiculture might face more pronounced threats in these regions than in others. In conclusion, given their substantial range shifts, invasive wasps will likely have increasingly negative impacts on global apiculture in the future.

The Effect of Model Input Uncertainty on the Simulation of Typical Pollutant Transport in the Coastal Waters of China

Route planning to evade potential pollution holds critical importance for aquaculture vessels. This study establishes a fish-feed pollutant drift model based on the Lagrangian particle tracking algorithm and designs four sets of sensitivity experiments in the East China Sea. The research investigates the impact of model input uncertainties on the drift trajectory, centroid position, and sweeping area of the fish-feed pollutants. Numerical results indicate that the uncertainty in the background flow field significantly affects the uncertainty in the centroid position and sweeping area in the numerical simulations. Specifically, when a 35% random error is added to the background flow field, the centroid shift distance reaches its maximum, and the sweeping area also attains its largest value. The uncertainty in the background wind field affects the centroid position of particles but to a much lesser extent compared to the background flow field. When considering only the uncertainty of the background wind field, the sweeping area does not significantly differ from the control experiment as the uncertainty of the background wind field increases. The initial release position has little effect on the drift direction of the fish-feed pollutants but does affect the drift distance; it has minimal impact on the trajectory but significantly affects the final position of the pollutant centroid. By analyzing the model uncertainties, this study reveals the key factors influencing the drift of fish-feed pollutants. This information is crucial for aquaculture vessels in planning routes, considering environmental factors, and reducing potential pollution risks.

Single-epoch and Differential Astrometric Microlensing of Quasars

We propose and discuss a new experimental approach to measure the centroid shift induced by gravitational microlensing in the images of lensed quasars (astrometric microlensing). Our strategy is based on taking the photocenter of a region in the quasar large enough as to be insensitive to microlensing as reference to measure the centroid displacement of the continuum. In this way, single-epoch measurements of astrometric microlensing can be performed. Using numerical simulations, we show that, indeed, the centroid shift monotonically decreases as the size of the emitting region increases, and only for relatively large regions, like the broad line region (BLR), does the centroid shift become negligible. This opens interesting possibilities to study the stratification of the different emitters in the accretion disk and the BLR. We estimate the amplitude of the centroid shifts for 79 gravitationally lensed images and study more thoroughly the special cases Q2237+030 A, RXJ1131-1231 A, PG1115+080 A2, and SDSS J1004+4112 A. We propose to use spectro-astrometry to simultaneously obtain the photocenters of the continuum and of different emission line regions since, with the precision of forthcoming instruments, astrometric microlensing by ∼1 M ⊙ mass microlenses may be detected in many quasar lensed images. When we consider more massive micro/millilenses, M ≳ 10 M ⊙, often proposed as the constituents of dark matter, the BLR becomes sensitive to microlensing and can no longer be used as a positional reference to measure centroid shifts. Differential microlensing between the images of a lensed quasar along several epochs should be used instead.

Orbital Hall diffraction and its application for vortex measurement.

We observe significant orbital angular momentum (OAM)-helicity-dependent centroid shifts in the Fraunhofer patterns for the far-field diffraction of optical vortex beams passing through a thin single wire, thus suggesting the orbital Hall effect (OHE) of light in diffraction. Based on the OHE with a thin cross wire, we further experimentally develop a compact and robust alignment-free method to measure the OAM states of light. These findings indicate that not only does the OHE of light offer insights into vortex diffraction with broken rotational symmetry, it may also provide a reliable and efficient way to simplify the vortex measurement for waves of different natures.

Global climate change-driven impacts on the Asian distribution of Limassolla leafhoppers, with implications for biological and environmental conservation.

Knowing the impacts of global climate change on the habitat suitability distribution of Limassolla leafhoppers contributes to understanding the feedback of organisms on climate change from a macroecological perspective, and provides important scientific basis for protecting the ecological environment and biodiversity. However, there is limited knowledge on this aspect. Thus, our study aimed to address this gap by analyzing Asian habitat suitability and centroid shifts of Limassolla based on 19 bioclimatic variables and occurrence records. Selecting five ecological niche models with the outstanding predictive performance (Maxlike, generalized linear model, generalized additive model, random forest, and maximum entropy) along with their ensemble model from 12 models, the current habitat suitability of Limassolla and its future habitat suitability under two Shared Socio-economic Pathways (SSP1-2.6 and SSP5-8.5) in the 2050s and 2090s were predicted. The results showed that the prediction results of the five models are generally consistent. Based on ensemble model, 11 potential biodiversity hotspots with high suitability were identified. With climate change, the suitable range of Limassolla will experience both expansion and contraction. In SSP5-8.52050s, the expansion area is 118.56 × 104 km2, while the contraction area is 25.40 × 104 km2; in SSP1-2.62090s, the expansion area is 91.71 × 104 km2, and the contraction area is 26.54 × 104 km2. Furthermore, the distribution core of Limassolla will shift toward higher latitudes in the northeast direction, and the precipitation of warmest quarter was found to have the greatest impact on the distribution of Limassolla. Our research results supported our four hypotheses. Finally, this research suggests establishing ecological reserves in identified contraction to prevent habitat loss, enhancing the protection of biodiversity hotspots, and pursuing a sustainable development path with reduced emissions.

Diagnostics of 3D explosion asymmetries of stripped-envelope supernovae by nebular line profiles

ABSTRACT Understanding the explosion mechanism and hydrodynamic evolution of core-collapse supernovae (SNe) is a long-standing quest in astronomy. The asymmetries caused by the explosion are encoded into the line profiles which appear in the nebular phase of the SN evolution – with particularly clean imprints in He star explosions. Here, we carry out nine different supernova simulations of He-core progenitors, exploding them in 3D with parametrically varied neutrino luminosities using the prometheus-hotb code, hydrodynamically evolving the models to the homologous phase. We then compute nebular phase spectra with the 3D Non-Local Thermodynamic Equilibrium spectral synthesis code extrass (EXplosive TRAnsient Spectral Simulator). We study how line widths and shifts depend on progenitor mass, explosion energy, and viewing angle. We compare the predicted line profile properties against a large set of Type Ib observations, and discuss the degree to which current neutrino-driven explosions can match observationally inferred asymmetries. With self-consistent 3D modelling – circumventing the difficulties of representing $^{56}$Ni mixing and clumping accurately in 1D models – we find that neither low-mass He cores exploding with high energies nor high-mass cores exploding with low energies contribute to the Type Ib SN population. Models which have line profile widths in agreement with this population give sufficiently large centroid shifts for calcium emission lines. Calcium is more strongly affected by explosion asymmetries connected to the neutron star kicks than oxygen and magnesium. Lastly, we turn to the near-infrared spectra from our models to investigate the potential of using this regime to look for the presence of He in the nebular phase.

Local climate change velocities and evolutionary history explain multidirectional range shifts in a North American butterfly assemblage.

Species are often expected to shift their distributions either poleward or upslope to evade warming climates and colonise new suitable climatic niches. However, from 18-years of fixed transect monitoring data on 88 species of butterfly in the midwestern United States, we show that butterflies are shifting their centroids in all directions, except towards regions that are warming the fastest (southeast). Butterflies shifted their centroids at a mean rate of 4.87 km year-1. The rate of centroid shift was significantly associated with local climate change velocity (temperature by precipitation interaction), but not with mean climate change velocity throughout the species' ranges. Species tended to shift their centroids at a faster rate towards regions that are warming at slower velocities but increasing in precipitation velocity. Surprisingly, species' thermal niche breadth (range of climates butterflies experience throughout their distribution) and wingspan (often used as metric for dispersal capability) were not correlated with the rate at which species shifted their ranges. We observed high phylogenetic signal in the direction species shifted their centroids. However, we found no phylogenetic signal in the rate species shifted their centroids, suggesting less conserved processes determine the rate of range shift than the direction species shift their ranges. This research shows important signatures of multidirectional range shifts (latitudinal and longitudinal) and uniquely shows that local climate change velocities are more important in driving range shifts than the mean climate change velocity throughout a species' entire range.

Analysis of potential niche shifts in alien pairs of mantis species (Insecta, Mantodea) with comments on the current taxonomic and ecological knowledge

Due to the pet and goods trade, several animals are now present in regions outside of their traditional native ranges. A peculiar situation has arisen in mantises, insects that are becoming more popular as pets: two genera (Hierodula and Tenodera) have begun to spread around the world, with two Hierodula species overlapping in Europe and two Tenodera species doing the same in North America. Such an event can lead to possible competition with both local taxa and alien congeneric sister species; the latter may reduce the impact of one of the invaders. Additionally, the situation allows the comparisons of niche shifts in displaced mantises, allowing us to understand whether such animals respect general patterns shown in terrestrial ectothermic invasive species. To do this, I adapted scripts from previous publications for analyzing niche overlap (Schoener’s D), niche expansion (E), and unfilling (U) through the centroid shift, overlap, unfilling, and expansion (COUE) scheme using presence records from GBIF and iNaturalist Research-Grade observations and bioclimatic variables available in BIOCLIM, selected according to variance inflation factor (VIF) values. I also evaluated the overlap between the sister species in the non-native range with D. Overall, there was relatively high niche expansion and unfilling patterns shared among the taxa, although species tended to have low abiotic overlap between native and alien ranges, and a relatively high niche overlap was present among congeneric species in the shared non-native area. However, such analyses may be biased due to chosen variables, taxonomic uncertainty, and lack of information on mantises’ ecology; particularly, the situation regarding H. tenuidentata/transcaucasica should be monitored and clarified, given the higher potential invasion risk of these species compared to other mantises and the uncertainties regarding which populations have reached Europe. Additionally, the biology of alien mantises should be studied in more detail in both native and non-native environments given the current critical lack of information.

Recent northward shift of tropical cyclone economic risk in China

The impact of tropical cyclones (TCs) has intensified with continued global warming and socio-economic development. Quantifying the TC economic exposure is a core element of economic risk assessment for TCs. The centroid of annual economic exposure to TCs in China shifted northward at a rate of 19.71 km per year from 2006 to 2020, where changes in the TC tracks contributed a northward shift of 11.22 km per year and changes in GDP distribution contributed a northward shift of 7.75 km per year. The northward shift of TC economic exposure centroid is more than twice as sensitive to the shift of GDP distribution as to that of TC tracks. The phenomenon of the northward shift in TC economic exposure is particularly evident in the subtropical zone in China. Further northward shift of TC exposure could potentially cause higher socio-economic losses in places underprepared for TC hazards. Our result provides references for TC disaster mitigation and preparedness in China.

Shaping ability of three instrumentation system in moderately curved canals: A micro-CT study.

This study aims to compare the shaping ability of three systems using micro-computed tomography (micro-CT). Moderately-curved mesial canals of 36 mandibular molars were assigned to three groups (n = 24); Protaper Next (PTN, 0.25, 0.06), WaveOne Gold (WOG, 0.25, 0.07), TruNatomy (TRN, 0.25, 0.04), and instrumentation was performed. Pre- and post-micro-CT scans were obtained. Canal volume and surface, structure model index (SMI), centroid shift, canal transportation, and untouched canal were analyzed. One-way ANOVA and Student's t-test were used for statistics. There was no difference in SMI, centroid shift, and centering ability between the study groups (p > .05). Removed dentin and canal surface changes were lower in TRN, while untouched dentin walls were higher (p < .05). Cross-sections became more rounded (p < .05), but not significant between groups (p > .05). Considering the removed dentin by TRN, it can be used in critical dentin thickness, such as the danger zone (DZ). PTN, WOG, and WOG kept the original canal course similarly. Untouched dentin by TRN (41%) was wider than PTN and WOG, consequently, meticulous irrigation is recommended. TRN, which provides a controlled increase in canal volume, can be used in thin dentin such as the DZ, however, its use should be supported by copious irrigation and brushing considering the rate of untouched dentin walls. RESEARCH HIGHLIGHTS: TRN presented a higher untouched dentin wall compared to PTN and WOG. Canal volume and surface changes were the lowest in the TRN group. The centering abilities were similar in PTN, WOG, and TRN.

Observing the galactic underworld: predicting photometry and astrometry from compact remnant microlensing events

ABSTRACT Isolated black holes (BHs) and neutron stars (NSs) are largely undetectable across the electromagnetic spectrum. For this reason, our only real prospect of observing these isolated compact remnants is via microlensing; a feat recently performed for the first time. However, characterization of the microlensing events caused by BHs and NSs is still in its infancy. In this work, we perform N-body simulations to explore the frequency and physical characteristics of microlensing events across the entire sky. Our simulations find that every year we can expect $88_{-6}^{+6}$ BH, $6.8_{-1.6}^{+1.7}$ NS, and $20^{+30}_{-20}$ stellar microlensing events which cause an astrometric shift larger than 2 mas. Similarly, we can expect $21_{-3}^{+3}$ BH, $18_{-3}^{+3}$ NS, and $7500_{-500}^{+500}$ stellar microlensing events which cause a bump magnitude larger than 1 mag. Leveraging a more comprehensive dynamical model than prior work, we predict the fraction of microlensing events caused by BHs as a function of Einstein time to be smaller than previously thought. Comparison of our microlensing simulations to events in Gaia finds good agreement. Finally, we predict that in the combination of Gaia and GaiaNIR data there will be $14700_{-900}^{+600}$ BH and $1600_{-200}^{+300}$ NS events creating a centroid shift larger than 1 mas and $330_{-120}^{+100}$ BH and $310_{-100}^{+110}$ NS events causing bump magnitudes &amp;gt;1. Of these, &amp;lt;10 BH and $5_{-5}^{+10}$ NS events should be detectable using current analysis techniques. These results inform future astrometric mission design, such as GaiaNIR, as they indicate that, compared to stellar events, there are fewer observable BH events than previously thought.

Unveiling climatic niches for deeper insights into invasion potential and enhanced distribution models of freshwater fishes

AbstractIntroduced species may exhibit variations in their preferred climatic niches between their native and introduced ranges, which can have important implications for the transferability of distribution models. In the Himalayan ecoregion, little is known about the geographic distribution and climatic niche overlap between native and introduced cold‐water species. Here, we used the COUE (centroid shift, overlap, unfilling, and expansion) framework to explore the invasive potential of rainbow (Oncorhynchus mykiss) and brown (Salmo trutta fario) trout and corresponding climatic niche overlap with native snow trout (Schizothorax plagiostomus and Schizothorax richardsonii) in the Indus and Ganges River basins. Although we found more stability in the climatic niche for O. mykiss (93%) than S. trutta (58%), both species do not conserve their climatic niches in this region (p &gt; 0.05). S. trutta has expanded more toward new environmental conditions (42%) compared to O. mykiss (7%). However, there are still available environmental gaps that O. mykiss and S. trutta can potentially occupy in the future. There was a higher overlap in climatic niches between S. plagiostomus and O. mykiss and between S. richardsonii and S. trutta. Observed shifts in climatic niches of these introduced species can negatively affect the transferability of distribution models, which may underestimate the assessments of habitat suitability for introduced trout in the Himalayas. Our study demonstrates that the information on climatic niche dynamics can inform the model‐building process and improve the transferability and predictive performance to better assess vulnerability of sensitive habitats to introduced species in the Himalayas and elsewhere.