Maximum Likelihood Research Articles

Spatiotemporal dynamics of LULC change and implications for sustainable urban growth in Saudi Arabia

This study investigates the spatiotemporal dynamics of land use and land cover (LULC) change in Saudi cities between 2013 and 2023. Using Landsat satellite imagery and a Maximum Likelihood Classifier, LULC changes are analyzed in nine cities to understand the impact of Saudi Arabia’s rapid urbanization following the oil crisis. The objectives are: (1) to evaluate the LULC changes in nine cities between 2013 and 2023; (2) to explore the spatiotemporal patterns of LULC changes in this period; and (3) to interpret the urban expansion that occurs in Saudi Arabia in the light of the kingdom sustainable development plan. The results identifiy four primary LULC change models: Urbanization, Vegetation Recovery, Land Degradation, and Ecological Transition Models. The Urbanization and Land Degradation Models determine Saudi Arabia’s urban growth trend, posing significant challenges to sustainable development. Most cities experienced substantial increases in impermeable surfaces and developed lands, while concurrently losing high terrain and barren areas. However, the small cities showed lower urbanization and land degradation rates than major cities, showing an opportunity to sustainably grow by adopting sustainable planning approaches. The study’s findings show that more targeted and comprehensive policies are needed to address the challenges of urbanization and land degradation, mitigate environmental impacts, and ensure long-term resilience. It underscores the importance of considering Ecological Urbanism in urban development plans.

Psychometric validation of the French version of two scales measuring general (HLS19-Q12) and navigational (HLS19-NAV) health literacy using the Rasch model

BackgroundTo examine the psychometrics properties of the French version of two scales measuring general (HLS19-Q12) and navigational (HLS19-NAV) health literacy (HL) using validation methods based on modern psychometric test theories: a Rasch model analysis.MethodsThe data on representative samples of the French adult population came from the Health Literacy Survey (N = 2 003), conducted in France in two waves (2020 and 2021), and from the third wave of SLAVACO study (N = 2 022), conducted in December 2021. A Rasch analysis was performed using a partial credit model with marginal maximum likelihood estimation adapted to polytomous data. Category probability curves were used to examine whether participants found it consistently difficult to distinguish between response options. Differential item functioning (DIF) was also examined for each item in the two scales as a function of age, gender, and economic status. A Person Separation Index (PSI) of 0.7 has conventionally been considered to be the minimum acceptable PSI level. Chi-square fit statistics, expressed as infit and outfit mean square statistics, were calculated for each item in the two scales. An acceptable fit corresponded to average values between 0.7 and 1.3. The dimensionality of the scales was assessed using Principal Components Analysis (PCA) on the residual correlation matrix to identify whether items are locally independent. Additionally, Smith’s method was employed to detect potential multidimensionality.ResultsThe PSI values for both scales were greater than 0.90. No disordered categories were observed. No evidence of significant DIF was found when associated with gender and economic status. However, two items for both scales had a DIF which was dependent on age but did not have a significant impact on scale scores between younger and older people. Minor local dependence was noted on the HLS19-NAV scale. However, a PCA and Smith’s method demonstrated the unidimensionality of the French version of the scales measuring general and navigational HL.ConclusionsOur results, based on a rigorous statistical analysis, verified the psychometric parameters of the French version of the HLS19-Q12 and HLS19-NAV scales. Despite strong correlation between both scales, each measured a different latent trait. Moreover, despite the fact that presence of DIF was weak, attention must nonetheless be paid when comparing scale response scores between young and older respondents.

Option Pricing Based on REGARCH Model with High-Frequency Information

As a prevalent tool for hedging risk, the trading volume of options has been growing increasingly in the derivatives market. Precision in the estimation of volatility leads to accurate option pricing. Since volatility is time-varying and has a clustering effect, GARCH class of volatility models is effective in modeling volatility precisely. This paper utilizes the realized EGARCH (REGARCH) model combined with Monte Carlo simulation to investigate the role of high-frequency information in option pricing. The parameter estimates of the REGARCH model are obtained via joint maximum likelihood estimation using observations on returns and realized measure. Applying the model to S&P options market, the empirical results show that the REGARCH model that using high-frequency data is more efficient than the model that only use daily closing prices, including the EGARCH, NGARCH and GJR-GARCH models. This paper demonstrates that incorporating realized measures into volatility models can improve the accuracy of option pricing. The REGARCH model contained more intraday trading information from high-frequency data, can measure the additional risk premiums and specific volatility shocks.

Modeling of Reversed Fréchet Distribution under Linear Normalizing

Extreme value theory (EVT) is becoming increasingly important as a suitable model of extreme events to represent phenomena in various fields of applications where extreme values may appear and have detrimental effects. In EVT, the Reversed Fréchet (RF) distribution is a special case of the Reversed generalized extreme value distribution (RGEVD) for modeling extreme data under linear normalizing. The purpose of this paper is divided into four objectives: Firstly, we discuss the practical aspects of the two methods that belong to the domain attraction of RF distribution. The second objective is to use RF distribution to model the behavior of two extreme air pollutants. The third objective is based on a diagnostics plot and hypothesis testing used to evaluate an appropriate shape of the tail distribution. Lastly, for the fourth objective, we attempt to obtain the return level period (RLP) that is expected to be exceeded. Maximum likelihood estimation (MLE) is derived and used to estimate the parameters of RF distribution. The results show that applications are significant for modeling by RF distribution in all cases of two air pollutants. Software that was used in all computations and graphics is the R statistical program with packages fExtreme and ismev.

Turbiditylenchus corticeus n. gen., n. sp. (Rhabditida: Anguinidae) from the bark of Eucalyptus macrorhyncha from the Australian Capital Territory

Summary A new genus and species of the Anguinidae, Turbiditylenchus corticeus n. gen., n. sp., was isolated from the bark of Eucalyptus macrorhyncha from southeastern Australia. Turbiditylenchus corticeus is readily differentiated from all recognised anguinid genera and is characterised primarily by a slender body, lateral field with six incisures, an anteriorly flattened lip region continuous with the body, delicate stylet 7.9-9.9 μm long, muscular median bulb containing a strongly refractive valve, post-vulval uterine sac 1.87-4.4 times vulval body diam., conical tail with pointed tip, and males with leptoderan bursa and spicules 20.5-25.8 μm in length. The phylogenetic relationships of the new species with other anguinid lineages were reconstructed using sequences of the small subunit ribosomal RNA (18S rRNA), the internal transcribed spacer region (ITS; comprising ITS1-5.8S-ITS2) and partial large subunit ribosomal RNA (28S rRNA D2-D3) genes based on Bayesian inference and maximum likelihood analyses. These analyses demonstrate the new species represents a lineage distinct from all other anguinids. Based on phylogenetic results we also transfer Ditylenchus parvicauda Gu, Ma, Castillo & Munawar, 2024 and Ditylenchus gracicauda Gu, Ma, Castillo & Munawar, 2024 to Ditylenchoides Subbotin & Ryss, 2024 as Ditylenchoides parvicauda n. comb. and Ditylenchoides gracicauda n. comb.

Teacher epistemic curiosity: how principal–teacher conversation supports it

PurposeThe purpose of this study was to introduce teacher epistemic curiosity for student learning into the leadership literature and to determine if school principals can support it. The inquiry was organized by the following research question: In what ways can principal–teacher conversations support teacher epistemic curiosity for student learning? The research question guided the review of literature on epistemic curiosity, eventually leading to the leadership practice of transformative leadership conversation (TLC). A hypothesized model on the relationship between TLC and epistemic curiosity for student learning was advanced from research on student and employee curiosity and self-determination theory.Design/methodology/approachThe hypothesized model was tested with a correlational research design. Teacher survey data were collected in December 2023 from a random sample of certified public school teachers from a metropolitan area in a southwestern state of the USA. Usable survey responses were received from 2,022 teachers, resulting in a 55% response rate. The hypothesized model was tested with structural equation modeling in AMOS 28 using robust maximum likelihood estimation. The latent models include measurement and structural components.FindingsResults confirm the hypothesized relationships among TLC, need-satisfaction and teacher epistemic curiosity. TLC and need-satisfaction both had strong, direct relationships with teacher epistemic curiosity for student learning. TLC explained approximately 20% of the variance in teacher curiosity and need-satisfaction explained approximately 18%. The combined model accounted for approximately 55% of the variance in teacher epistemic curiosity.Originality/valueThe study emerged from robust evidence on the essential function of curiosity for knowing, learning, performance and life well-being, as well as limited research on social processes that leaders can leverage to stimulate teachers’ motivation to understand how their students learn. Curiosity is an inner energy behind learning; it fuels an innate drive to explore, know, create, design and adapt to our surroundings. Schools and classrooms come to life when teachers and students engage in learning from a place of curiosity, making this motivational resource worthy of leadership attention.

Enhancing Efficiency: Halton Draws in the Generalized True Random Effects Model

This paper measures the impact of the number of Halton draws in excess of ⌈n⌉ on technical efficiency in the generalized true random effects (four-component) stochastic frontier model estimated by simulated maximum likelihood. A substantial set of Monte Carlo simulations demonstrates that increasing the number of Halton draws to ⌈n3/4⌉ (⌈n2/3⌉) decreases the mean squared error of the total technical efficiency estimates by 6.1 (4.9) percent. Furthermore, increasing the number of Halton draws either improves or has no detrimental impact on correlation, mean squared error, relative bias, and upward bias for persistent, transient, and total technical efficiency. An energy sector application is included, to demonstrate how these issues can arise in practice, and how increasing Halton draws can improve parameter and efficiency estimates in empirical work.

First Report of Neofusicoccum nonquaesitum Causing Branch Dieback of English Walnut (Juglans regia) in the Maule Region, Chile

English walnut (Juglans regia) cultivation has been expanding in recent years in Chile, with a surface of 9,000 ha planted in the Maule Region (35° 26' S, 71° 40' W), central Chile. In a field survey conducted between August (2022) and January (2023) in three localities of the Maule Region, several declined trees were observed. English walnuts exhibited small chlorotic leaves, cankers, dead twigs, and dieback of branches, with an incidence of 10 to 35% of trees affected per orchard. Internally, diseased branches exhibit brown to dark brown wood cankers. Symptomatic branches (n = 30) were collected and surface disinfected with 96% ethanol, and flamed. Pieces of wood (approximately 5 mm) were placed on potato dextrose agar (PDA), supplemented with 0.005% tetracycline, 0.01% streptomycin, and 0.1% Igepal CO-630 (Díaz et al. 2018), and incubated at 22°C for 5 days in darkness. Four isolates (VLC-1-6-20, VLC-1-10-20, VLC-1-12-20, and VLC-1-15-20) exhibited moderate growth rates (16.4 mm/day), developing a white hue to olivaceous black colonies after 7 days at 22°C on PDA. Chlamydospores were absent. Black pycnidia were formed individually or in clusters. The isolates produced aseptate, hyaline, and fusiform, with base truncate conidia measuring 24.8 ± 1.6 x 6.8 ± 0.63 µm (l/w = 3.1; n = 50). The four isolates characterized were amplified using of the internal transcribed spacer (ITS1/ITS4), a portion of beta-tubulin (Bt2a/Bt2b), and part of the translation elongation factor 1- α (EF1-728/EF1-968) genes (Phillips et al. 2013). Blast analyses showed 100, 99 and 100 % identity with ex-type isolate PD-484 of Neofusicoccum nonquaesitum for ITS (deposited as GenBank accession no. PP697845 to PP697848), Bt (PP789576 to PP789579) and EF1 (PP830824 to PP830827) regions, respectively. Combined phylogenetic analysis using MEGA 7 software and the maximum likelihood test clustered the four isolates with ex-type of N. nonquaesitum. Pathogenicity was performed using two isolates (VLC-1-6-20 and VLC-1-10-20), which were inoculated in healthy tree walnuts cv. Chandler (8 years old), using 40 μl of mycelial suspension (105 fragments of mycelium/ml) on rounded wounds in the middle of each attached young branch (n=30 branches) (Twizeyimana et al. 2013). Sterile distilled water was used as a control treatment. Pathogenicity tests were repeated twice. After 6 months, necrotic streaks with mean lengths of 13 mm and 28 mm were observed in the middle of wounded young branches. No necrotic lesions were observed in the control treatments. Reisolation of N. nonquaesitum was positive (100%) only from inoculated branches and molecularly identified (EF1-a), fulfilling Koch’s postulates. Previously, N. nonquaesitum has been reported causing dieback on English walnut in California (Chen et al. 2014). To our knowledge, this is the first report of N. nonquaesitum causing canker and branch dieback of English walnut in central Chile. Previously, Diplodia mutila, Dothiorella sarmentorum, and N. austral have been associated with walnut dieback in Chile (Díaz et al. 2018; Iqbal et al. 2023; Barcos et al. 2023). In conclusion, it is imperative to implement epidemiological studies to avoid the spread and severity of branch dieback of walnuts in the Maule region, central Chile.

Optimal Estimation of Reliability Parameters for Modified Frechet-Exponential Distribution Using Progressive Type-II Censored Samples with Mechanical and Medical Data

The aim of this research is to estimate the parameters of the modified Frechet-exponential (MFE) distribution using different methods when applied to progressive type-II censored samples. These methods include using the maximum likelihood technique and the Bayesian approach, which were used to determine the values of parameters in addition to calculating the reliability and failure functions at time t. The approximate confidence intervals (ACIs) and credible intervals (CRIs) are derived for these parameters. Two bootstrap techniques of parametric type are provided to compute the bootstrap confidence intervals. Both symmetric loss functions such as the squared error loss (SEL) and asymmetric loss functions such as the linear-exponential (LINEX) loss are used in the Bayesian method to obtain the estimates. The Markov Chain Monte Carlo (MCMC) technique is utilized in the Metropolis–Hasting sampler approach to obtain the unknown parameters using the Bayes approach. Two actual datasets are utilized to examine the various progressive schemes and different estimation methods considered in this paper. Additionally, a simulation study is performed to compare the schemes and estimation techniques.

First Report of Powdery Mildew Caused by Golovinomyces ambrosiae on Symphyotrichum subulatum in China.

Symphyotrichum subulatum (Michx.) G. L. Nesom (syn. Aster subulatus), an annual herb in the Asteraceae family, is native to North America. Nowadays, it has become an invasive weed in several provinces of China, including Jiangsu, Zhejiang, and Sichuan (Li and Xie, 2002). Despite being invasive, this species holds significance in Chinese medicine, where it is used for the external treatment of eczema and swollen sore poison (Hu, 2020). In June 2023, symptoms of powdery mildew were observed in S. subulatum populations in Deyang and Nanchong, Sichuan Province, China. About 32.73% among 55 surveyed S. subulatum plants showed signs of infection. Symptoms initially appeared as small, scattered white powdery patches on the leaves, which enlarged and coalesced over time. Subsequently, hyphal growth forming extensive conidia covered up to 90% of the leaf area on both surfaces (Fig. S1A, B), and the infected leaves withered and fell off (Fig. S1A). A specimen was archived at China West Normal University (SsPM-ZL). Conidiophores were cylindrical and erect, 66.4 to 183.2 µm (avg. 108.2±40.8 μm) in length (n=30) (Fig. S1C). Conidia, produced singly, were ellipsoid-ovoid to nearly cylindrical, measuring 29.5 to 36.7 μm in length (avg. 32.9±2.6 μm) and 16.0 to 19.9 μm in width (avg. 17.4±1.3 μm), lacking distinct fibrosin bodies (n=30) (Fig. S1D). Under a scanning electron microscope, turgid conidia displayed reticulate wrinkles on the surface, with gentle contractions or bulges at both poles (Fig. S1E, F). Based on these characteristics, the powdery mildew fungus was consistent with the genus Golovinomyces (Bradshaw et al. 2022a). To confirm the identity of the causal fungus of specimen (SsPM-ZL), the calmodulin (CAM), RNA polymerase II subunit (RPB2), glyceraldehyde-3-phosphate dehydrogenase (GAPDH), glutamine synthetase (GS), and the internal transcribed spacer (ITS) were amplified using PMCAMF/R, PMRPB2F/R, PMGAPDH1/3R, PMGSF/R, and PM5/ITS4 primers (Bradshaw et al. 2022b), and deposited in GenBank (CAM: OR761878; RPB2: OR761881; GAPDH: OR761879; GS: OR761880; ITS: OR758452). BLAST analysis showed 99 to 100% identity with the sequences of Golovinomyces ambrosiae (FH00941234) for CAM (ON101658, 99.65%), RPB2 (ON119165, 100%), GS (ON075690, 99.78%), and ITS (ON073876, 99.47%). Phylogenetic analysis was performed in MEGAX with maximum likelihood method (Kumar et al. 2016) and clustered SsPM-ZL into the G. ambrosiae clade with a 100% bootstrap support value based on the concatenated sequences of CAM, RPB2, GAPDH, GS and ITS (Fig. S2). Combining morphological and phylogenetic analyses, SsPM-ZL was identified as Golovinomyces ambrosiae. To evaluate pathogenicity, leaves of 3 healthy potted S. subulatum plants (3 leaves per plant) were inoculated by gently pressing them with diseased leaves, while 3 non-contact plants were used as control. Plants in two groups were incubated in separate greenhouses maintained at 27±1°C, with a photoperiod of 14 hours and a relative humidity of 80%. After 7 days, the inoculated plants exhibited symptoms of powdery mildew (Fig. S1H, J), while the control plants remained asymptomatic (Fig. S1G, I). Morphological characteristics of the artificially induced powdery mildew were consistent with those on naturally infected plants. Powdery mildew caused by G. ambrosiae has been reported affecting Helianthus tuberosus (Huang et al. 2017) and Bidens pilosa (Mukhtar et al. 2022) in China. To our knowledge, this is the first report of powdery mildew caused by G. ambrosiae on S. subulatum in China. Our finding will provide the fundamental knowledge for future powdery mildew diagnosis and the development of potential control strategies.

Phylogenetics and reticulation among koelerioid clades, part I: Contraction of Trisetum, expansion of Acrospelion, Graphephorum, and Tzveleviochloa; Graciliotrisetum gen. nov. and resurrection of Aegialina (Poaceae, Pooideae, Poeae, Aveninae)

AbstractKoelerioid grasses (subtribe Aveninae, tribe Poeae; Pooideae) resolve into two major clades, here called Koelerioid Clades A and B. Phylogenetic relationships among koelerioid grasses are investigated using plastid DNA sequences of rpl32‐trnL, rps16‐trnK, rps16 intron, and ITS regions, focusing on Trisetum, Acrospelion, and some annual species (Rostraria p.p. and Trisetaria p.p.) closely related to Trisetum flavescens in Koelerioid Clade A. Phylogenetic analyses of several selected data sets performed for 80 taxa and using maximum likelihood and Bayesian methods, revealed mostly congruent topologies in the nuclear and plastid trees, but also reticulation affecting several lineages. Trisetum is restricted to one species, T. flavescens, which is a sister to the clade formed by Trisetum gracile and Trisetaria aurea. The latter two species are classified here in the genus Graciliotrisetum gen. nov. The sister clade includes three species of Rostraria and Trisetaria lapalmae, all of which are classified here in a resurrected genus, Aegialina, which includes four species. Acrospelion is enlarged to include 13 species after the addition of other species formerly classified in Trisetum sect. Trisetum and T. sect. Acrospelion. We also transfer Trisetum ambiguum, Trisetum longiglume, and Koeleria mendocinensis to Graphephorum; and Helictotrichon delavayi to Tzveleviochloa, expanding these genera to eight and six species, respectively. We evaluate cases of reticulate evolution between Koelerioid Clades A and B and within Koelerioid Clade A, which probably gave rise to Graphephorum, Rostraria cristata, and Rostraria obtusiflora. Finally, we comment on polyploidy and biogeographic patterns in koelerioid grasses. We propose the following 26 new combinations: Acrospelion alpestre, Acrospelion altaicum, Acrospelion argenteum, Acrospelion bertolonii, Acrospelion buschianum, Acrospelion buschianum subsp. transcaucasicum, Acrospelion fuscum, Acrospelion laconicum, Acrospelion macrotrichum, Acrospelion rigidum, Acrospelion rigidum subsp. teberdense, Acrospelion tamonanteae, Acrospelion velutinum, Aegialina lapalmae, Aegialina pubescens, Aegialina pumila, Aegialina pumila subsp. fuscescens, Aegialina salzmannii, Aegialina salzmannii subsp. cossoniana, Graciliotrisetum aureum, Graciliotrisetum gracile, Graphephorum ambiguum, Graphephorum longiglume, Graphephorum mendocinense, Graphephorum orthochaetum, and Tzveleviochloa delavayi. Lectotypes are designated for the names Aegialitis tenuis, Aira melicoides, Avena aspera var. parviflora, Avena delavayi, Koeleria grisebachii var. mendocinensis, Koeleria pubescens subsp. cossoniana, Koeleria pumila, Koeleria salzmannii, Phalaris pubescens, Trisetum aureum, Trisetum cernuum, Trisetum fuscescens, Trisetum longiglume, and Trisetum wolfii; and we designate one neotype for Alopecurus litoreus.

Genetic Evidence Supporting a Causal Role of Snoring in Keratoconus: A Bidirectional Mendelian Randomization Study.

To clarify the controversial causal association between snoring and keratoconus (KCN), which is crucial in clinical prevention and treatment. This is a 2-sample bidirectional mendelian randomization (MR) case-control study. MR is an innovative method that uses genetic variation as a natural experiment to investigate the causal relationships between potentially modifiable risk factors and health outcomes in observational data. The single nucleotide polymorphisms associated with snoring were retrieved from the UK biobank cohort with 218,346 participants (61,792 cases and 156,554 controls). The summary statistics of KCN were obtained from the European ancestry with 209,598 subjects (311 cases and 209,287 controls). The inverse-variance-weighted method was applied as the primary estimate, whereas weighted median and MR-pleiotropy residual sum and outlier played a subsidiary role. Elevated risk of snoring showed a robust causal effect on KCN (inverse-variance-weighted: causal effect = 9.821, 95% confidence interval [CI], 1.944-17.699, P = 0.015), which was consistent with complementary methods of the weighted median (causal effect = 11.117, 95% CI, 2.603-19.631, P = 0.010), maximum likelihood (causal effect = 10.245, 95% CI, 3.967-16.523, P = 0.001), and MR-pleiotropy residual sum and outlier (causal effect = 9.793, 95% CI, 2.316-17.269, P = 0.028). However, there was no causality of KCN on the increasing risk of snoring. This study provides genetic evidence supporting the causal role of snoring on KCN. Our findings provide new insights into potential strategies to manage KCN.

Seven mitochondrial genomes of tribe Hylurgini (Coleoptera: Curculionidae: Scolytinae) in Eurasia and their phylogenetic analysis.

The Hylurgini tribe (Coleoptera: Curculionidae: Scolytinae) comprises commercially significant bark beetles, including invasive species within the genera Dendroctonus and Hylurgus. These invasive species coexist with native Tomicus species of Hylurgini and cooperatively infest host trees in China. However, we lack sufficient mitochondrial genome data of Hylurgini to conduct phylogenetic studies, clarify the phylogenetic relationships of the above species, and improve the understanding of niche divergence and common hazards. Here, we sequenced and analyzed the mitochondrial genomes of seven Hylurgini species, including Dendroctonus valens, Hylurgus ligniperda, Hylurgus micklitzi, Tomicus piniperda, Tomicus brevipilosus, Tomicus minor and Tomicus yunnanensis. All sequenced mitochondrial genomes ranged from 15,339 bp to 17,545 bp in length, and their AT contents ranged from 73.24% to 78.81%. The structure of the seven mitochondrial genomes was consistent with that of ancestral insects. Based on 13 protein-coding genes from the reported mitochondrial genomes of 29 species of bark beetles, we constructed phylogenetic trees using maximum likelihood and Bayesian inference methods. The topology of the two phylogenetic trees was almost consistent. The findings elucidated the taxonomy classification of Hylurgini and the evolutionary connections of its sister taxa within the Scolytinae. This study offers insights for examining the evolutionary connections between invasive and native bark beetles, as well as the molecular identification and detection of newly invading species.

A note on potential gains in precision of radiation risk estimates from joint analysis.

In estimating radiation-related risk of cancer and other diseases based on the RERF Life Span Study (LSS), joint analyses can be performed where multiple health outcome endpoints are combined in the same model, allowing some parameters to be estimated in common among all endpoints with possible increase in precision of radiation risk and other model parameter estimates. Using as a basis excess relative risk (ERR) and excess absolute risk (EAR) models of the type commonly used in analysis of LSS data at RERF, we use maximum likelihood theory to compute the asymptotic relative standard error of endpoint-specific radiation effect and other parameter estimates using joint analyses as compared to traditional independent analysis. We show that some gains in precision of endpoint-specific radiation risk parameter estimates can be achieved by sharing effect modifier and other model parameters, but only small or negligible gains in precision are achieved for endpoint-specific background modifying or effect modifying parameters when other model parameters are shared. The magnitude of the precision gain for radiation risk estimates depends on the number of endpoints, the baseline incidence rate of the endpoint, and the type of model being used.

Russian exports amid geopolitical instability: The case of physical and transitional climate risks

The paper examines the impact of physical and transitional climate risks, which to some extend shape the geopolitical situation in the world, on Russian exports. The gravity model of international trade was employed to model the existing relationship. Estimation of the gravity equation by means of the Poisson Pseudo Maximum Likelihood (PPML) method using data on Russian export flows to 72 countries over the period 2010—2021 revealed that climate change and the ambitions of trading partner states towards low-carbon development determine the dynamics of Russian exports. In particular, national physical climate risks have a detrimental impact on Russia’s exports due to the destruction of infrastructure, loss of capital, reduced quality and availability of natural resources, and increased social tensions. Extreme climatic events and climate change measures in trading partner countries spur the development of Russian exports. Namely, physical climate risks of importing countries may increase the demand for key Russian goods for economic recovery purposes. Changes during the transition to a low-carbon economy in trading partner countries also generate opportunities for Russian export growth due to the country’s role as a major supplier of energy and mineral products, as well as technologies for the alternative energy production and electrification of transport

Willingness to Pay for Improved Groundwater due to BMPs in PEI.

This study uses stated preference techniques to evaluate the willingness to pay for improved groundwater in PEI, which allows us to estimate the social cost of nitrogen in this region. 'Beneficial Management Practices' (BMPs) are often employed in PEI's agricultural sector, to improve crop yields but also reduce adverse environmental effects such as nitrogen leaching that can affect ground and surface waters. PEI residents were surveyed to estimate a dollar value of improved water quality due to reduced nitrogen leaching due to BMPs. From the responses to a double-bounded dichotomous choice survey, models using maximum likelihood estimation showed that residents of PEI were willing to pay roughly $230 per year to see a reduction in nitrogen of either 20% or 50%, which translated to $5-13 per kg of nitrogen reduced. However, excluding 'yeah-sayers' and protest votes suggests that WTP is lower for the 20% reduction and increases as nitrogen reduction increases. Thus, a social cost of $13/kg should be considered an upper bound in PEI. WTP values, as well as estimates of the social cost of nitrogen are similar to values in previous literature. We find that variables such as cell phone usage, belief that farmers should pay for BMPs, and spending on water filtration have a statistically significant impact on WTP. Other variables are significant in some model specifications, however many demographic variables such as employment status and education do not affect WTP.

Joint modelling of longitudinal ordinal and multi-state data.

Joint modeling of longitudinal and survival data is increasingly used in biomedical studies. However, existing joint models are not applicable to model the longitudinal ordinal responses with non-ignorable missing values caused by the occurrence of events in a multi-state process. In this article, we introduce a joint model for longitudinal ordinal measurements and multi-state data. Our proposed joint model consists of two sub-models: a proportional odds sub-model for longitudinal ordinal measurements and a multi-state sub-model with transition-specific proportional hazards for times of transitions between different health states, both linked by shared random effects. The model parameters were estimated employing the maximum likelihood method for a piecewise constant baseline hazard function. The proposed joint model is evaluated in a simulation study and, as an illustration, it is fitted to real data from people with human immunodeficiency virus.

Hemoglobin level and common mental disorder among school adolescent girls in Central Ethiopia: Structural Equation Model.

The prevalence of common mental disorder (CMD) and anemia is observed to be on the rise over time, adversely affecting the health and overall quality of life among adolescents. Extensive literature corroborates the significant impact of anemia on cognitive development, intelligence and developmental milestones. Nevertheless, the linkage between hemoglobin level and CMD emerging during adolescence remains relatively unexplored. Thus, the objective of this study was to investigate the association between hemoglobin level and CMD as well as the mediating factor among school adolescent girls residing in Central Ethiopia. A cross-sectional study design was conducted among adolescent girls attending schools in Silti Woreda, Central Ethiopia, comprising a total sample size of 516 individuals during the period from October 2-20, 2023. Hemoglobin level was adjusted for altitude, while CMD was evaluated utilising the summation score of a 20-item Self-Reporting Questionnaire. Data were analysed through fitting Structural Equation Model and the maximum likelihood estimation method. Goodness of fit was assessed using the χ2The -test statistic, Comparative Fit Index, Root Mean Square Error of Approximation, Standardised Root Mean Square Residual, Non-Normed Fit Index, Pclose and coefficient of determination (R2). The prevalence of CMD was 22.3% (95% CI: 18.6%-25.8%). Hemoglobin level (UTE = -0.73, CI: -0.93, -0.53) and experience of morbidity symptoms (UTE = 1.05; CI: 0.74, 1.38) were significantly associated with CMD. Furthermore, hemoglobin level is significantly influenced by morbidity frequency symptoms (UDE = -0.63, CI = -0.77, -0.49) and animal source food (ASF) (UDE = 0.09, CI = 0.01, 0.17). Hemoglobin level has been identified as a significant mediator of the experience of morbidity symptoms and ASF on CMD. However, household food insecurity and wealth index had no significant association with CMD. A significant proportion of adolescent girls face CMD, often linked to a lower hemoglobin level. Having a significant association with CMD, the hemoglobin level is found to mediate a significant effect of morbidity symptom experience and ASF on CMD. Hence, addressing early infection prevention, promoting ASF and treating anemia are promptly needed.

Terraces in species tree inference from gene trees

A terrace in a phylogenetic tree space is a region where all trees contain the same set of subtrees, due to certain patterns of missing data among the taxa sampled, resulting in an identical optimality score for a given data set. This was first investigated in the context of phylogenetic tree estimation from sequence alignments using maximum likelihood (ML) and maximum parsimony (MP). It was later extended to the species tree inference problem from a collection of gene trees, where a set of equally optimal species trees was referred to as a “pseudo” species tree terrace which does not consider the topological proximity of the trees in terms of the induced subtrees resulting from certain patterns of missing data. In this study, we mathematically characterize species tree terraces and investigate the mathematical properties and conditions that lead multiple species trees to induce/display an identical set of locus-specific subtrees owing to missing data. We report that species tree terraces are agnostic to gene tree heterogeneity. Therefore, we introduce and characterize a special type of gene tree topology-aware terrace which we call “peak terrace”. Moreover, we empirically investigated various challenges and opportunities related to species tree terraces through extensive empirical studies using simulated and real biological data. We demonstrate the prevalence of species tree terraces and the resulting ambiguity created for tree search algorithms. Remarkably, our findings indicate that the identification of terraces could potentially lead to advances that enhance the accuracy of summary methods and provide reasonably accurate branch support.

Asymptotic Confidence Intervals for MRL and TVaR of the Inverse Weibull Distribution with Type II Censored Data

We consider interval estimation for the parameters, the Mean Residual Life (MRL) and the Tail Value at Risk (TVaR) of the inverse Weibull distribution. We constructed the confidence intervals based on the asymptotic normality of the maximum likelihood estimator in addition to intervals based on the asymptotic Chi-Square distribution of the likelihood ratio (LR) statistic under Type II Censoring. The performance of intervals is investigated and compared using the lower, upper, and total error rates, in addition to expected lengths using simulation. We found that LR intervals showed better overall performance and are more accurate than confidence intervals based on the asymptotic normality of maximum likelihood estimator.