Limited Number Research Articles

PCAOB Enforcement: Toothless Body of Law or a Bite That Packs a Punch?

SUMMARY The value of PCAOB enforcement was questioned in a 2019 Project on Government Oversight report, calling it a “toothless body of law.” However, the argument focused narrowly on the limited number of PCAOB enforcements imposed on Big 4 auditors without consideration of whether they motivate positive audit quality effects more broadly. In this paper, we summarize key findings by Lamoreaux, Mowchan, and Zhang (2023) regarding whether PCAOB enforcement provides spillover benefits, deterring audit failures. LMZ find audit quality improvements among nonsanctioned auditors following PCAOB enforcement, but the pattern of this spillover varies with auditor and enforcement characteristics. Their results suggest that even PCAOB enforcements that seem limited in scope can offer protections to investors more broadly through spillover benefits. In conclusion, we discuss potential avenues through which additional spillover benefits could occur, resulting from audit firm organizational structures, remote work environments, and emerging trends in PCAOB rule-making and enforcement. JEL Classifications: G38; M42; M48.

Restoring the discontinuous heat equation source using sparse boundary data and dynamic sensors

This study focuses on addressing the inverse source problem associated with the parabolic equation. We rely on sparse boundary flux data as our measurements, which are acquired from a restricted section of the boundary. While it has been established that utilizing sparse boundary flux data can enable source recovery, the presence of a limited number of observation sensors poses a challenge for accurately tracing the inverse quantity of interest. To overcome this limitation, we introduce a sampling algorithm grounded in Langevin dynamics that incorporates dynamic sensors to capture the flux information. Furthermore, we propose and discuss two distinct dynamic sensor migration strategies. Remarkably, our findings demonstrate that even with only two observation sensors at our disposal, it remains feasible to successfully reconstruct the high-dimensional unknown parameters.

Influence of Taekwondo Training as a Martial Art Sport on Enhancing Mental Wellness of Security Officers in Kenya

Purpose: The purpose of this research was to investigate whether or not training in taekwondo as a martial art sport has a positive impact on the mental health of Kenyan security officers.
 Methodology: The study used a desk top approach where literature was sought from different sources. The research was carried out with consideration given to previous theoretical literature, both published and unpublished.
 Findings: Problems with mental wellness is a serious societal and work related issue that has numerous ramifications, including far-reaching social and economic impact in Kenyan security officers. However, a significant number of security officers do not seek help when they are experiencing issues with their mental wellness. Research in this area is scant, but there are suggestions that training in Taekwondo as martial arts sport may be an effective sports-based intervention for mental wellness, and that it may provide an affordable alternative to psychological therapy to security officers both public and private.
 Unique contribution to theory, practice and policy: Uncertainty regarding the validity and trustworthiness of previous research is unfortunately caused by the limited number of studies that are relevant to the topic at hand, in addition to other methodological issues.

Influence of the gut and airway microbiome on asthma development and disease.

There are ample data to suggest that early-life dysbiosis of both the gut and/or airway microbiome can predispose a child to develop along a trajectory toward asthma. Although individual studies show clear associations between dysbiosis and asthma development, it is less clear what (collection of) bacterial species is mechanistically responsible for the observed effects. This is partly due to issues related to the asthma diagnosis and the broad spectrum of anatomical sites, sample techniques, and analysis protocols that are used in different studies. Moreover, there is limited attention for potential differences in the genetics of individuals that would affect the outcome of the interaction between the environment and that individual. Despite these challenges, the first bacterial components were identified that are able to affect the transcriptional state of human cells, ergo the immune system. Such molecules could in the future be the basis for intervention studies that are now (necessarily) restricted to a limited number of bacterial species. For this transition, it might be prudent to develop an exvivo human model of a local mucosal immune system to better and safer explore the impact of such molecules. With this approach, we might move beyond association toward understanding of causality.

Abstract A017: Prevalence and significance of common molecular alterations in Tp53-mutated uterine serous carcinoma

Abstract Background: Uterine Serous Carcinoma (USC) is an aggressive subtype of endometrial cancer characterized by ubiquitous TP53 mutations and high replication stress. The resulting dependency on DNA damage repair and cell cycle checkpoints triggers sensitivity to the abrogation of the G2 checkpoint using Wee1 inhibitors (Wee1i) such as Azenosertib. Wee1i sensitivity has been associated with high levels of Cyclin E1, which may result from gene amplification of CCNE1 or the alteration of its ubiquitin ligase FBXW7 1. In addition, signaling activity of Wee1 is controlled by the PP2A protein phosphatase2, the regulatory subunit of which, PPP2R1A, is frequently mutated in USC. Comprehensive molecular profiling has only been performed in a limited number of cohorts and the distribution and relationship of these candidate biomarkers to one another and other molecular alterations is unclear. Methods: Genomic and phenotypic data from TP53-mutated USC were collected from TCGA-pancancer (N=95), AACR-GENIE v13 (N=796) or Azenosertib studies (N=46). The mutational status of 6 mutated genes and 1 gene set (HRR; N=14 genes) was determined from pathogenic alterations. The prevalence of altered genes was measured accounting for variable gene inclusion for each assay. Cross-cohort prevalence or gene-pair mutual exclusivity and co-occurrence were measured using Fisher exact test. Results: The prevalence of alterations in TCGA, AACR-GENIE and Azenosertib cohorts were similar for PIK3CA (37%, 34%, 28%), FBXW7 (21%, 17%, 8%), PPP2R1A (37%, 30%, 29%), PIK3R1 (13%, 12%, 8%), HRR genes (7%, 7%, 15%), or amplification of ERBB2 (19%, 14%, 9%). In contrast, prevalence of CCNE1 amplification in TCGA was significantly higher (27% vs 16% and 7%), which could reflect differences in patient population or methodology. Of all 28 combinations, no gene pairs were significantly co-mutated and only FBXW7 and PPP2R1A were mutually exclusive in both TCGA and AACR-GENIE. The prevalence of the corresponding co-alterations was similar between cohorts: mutated in both (3% in both), neither (45% and 57%), FBXW7 only (18% and 13%) or PPP2R1A only (34% and 27%). Furthermore, alterations in genes encoding components of the PI3K enzyme (PIK3CA or PIK3R1) affected 45% of the patients in either cohort. None of the mutational status or derived subtypes had prognostic value (TCGA). Similarly, apart from CCNE1 amplification, none of the subtypes evaluated were associated with Cyclin E1 expression as measured by reverse phase protein array (TCGA) or immunohistochemistry (Azenosertib studies). Conclusion: Important processes related to CCNE1, FBXW7 and PPP2R1A function have been associated with high replication stress and Wee1i sensitivity. Our analyses suggest that alterations in these genes are common and sometimes mutually exclusive, leading to broad genomic instability across USC and suggesting an explanation for the clinical efficacy that has been seen with Azenosertib and other Wee1i. Citation Format: Olivier Harismendy, Jianhui Ma, Adrian M. Jubb, Carrie Brownstein, Mark R. Lackner, Ramez N. Eskander, Joyce Liu, Shannon N. Westin. Prevalence and significance of common molecular alterations in Tp53-mutated uterine serous carcinoma [abstract]. In: Proceedings of the AACR Special Conference on Endometrial Cancer: Transforming Care through Science; 2023 Nov 16-18; Boston, Massachusetts. Philadelphia (PA): AACR; Clin Cancer Res 2024;30(5_Suppl):Abstract nr A017.

Experimental effect of wind and heavy rain on increased splash erosion using rainfall simulator

To investigate the erosion process that occurs, rainfall simulation is used with a model scale for natural rain events in laboratory conditions. The calculation of erosion and any soil erosion with a slope setting of 5% was carried out experimentally on a laboratory scale using a rain simulator and adding wind using a 2-inch snail blower. Experiments carried out in the laboratory included erosion tests driven by rain and erosion tests by rain, which were given additional wind variables. Rain intensity used for testing is using discharge 1 litre/minute,1.5 litre/minute, and 2 litre/minute as a representative variation of rainfall. The occurrence of rain and wind simultaneously within a certain period will cause greater loss of soil. Although many studies have been conducted on the effects of rain and the combined effects of wind on soil erosion, only a limited number of studies have focused on the combination of the two variables that occur together. The results showed that in the applied rain intensity and wind factor, the collision of the kinetic energy of the rain driven by the wind resulted in higher erosion when compared to that without the influence of the wind.

Rapid Determination of Diverse Ganoderic Acids in Ganoderma Using UPLC–MS/MS

Background:: Ganoderma is known for its pharmaceutical, nutritional, and functional benefits. Its primary bioactive components are ganoderic acids. However, previous quantification methods only analyzed an individual or limited number of ganoderic acids. This study aims to develop a reliable method for simultaneously quantifying the major ganoderic acids to enhance Ganoderma quality control and study its active ingredients. Methods:: We developed a rapid quality assessment method to simultaneously determine the eleven ganoderic acids in Ganoderma using ultra-high performance liquid chromatography-tandem mass spectrometry (UPLC-MS/MS). The sample extraction method, along with mass spectrometric detection and chromatographic separation conditions was optimized. The separation was carried out using the ACQUITY UPLC BEH C18 column with a gradient elution of 0.1% (v/v) formic acid in water and acetonitrile. The mass spectrometry utilized negative mode electrospray ionization (ESI), with quantitative analysis being carried out in the MRM mode. Results:: The calibration curves showed good correlation coefficients (r2 > 0.998). The recovery range was 89.1–114.0%. The intra-day and inter-day relative standard deviation (RSD) were below 6.8% (n = 6) and 8.1% (n = 6), respectively. Furthermore, the detection and quantification limits were 0.66–6.55 μg/kg and 2.20–21.84 μg/kg, respectively. All 11 ganoderic acids in the sample solution remained stable at room temperature for 72 hours. A total of 11 ganoderic acids were quantified in the 13 Ganoderma samples. The levels of ganoderic acids were higher in Ganoderma lucidum than in Ganoderma sinense. Conclusion:: The method developed in this study can quantify ganoderic acids in Ganoderma lucidum, thus establishing a technical foundation for evaluating the Ganoderma quality.

Impact of the design of adult mental health inpatient facilities on healthcare staff: a mixed methods systematic review

ObjectivesMental health inpatient facilities are increasingly focusing on creating therapeutic, person-centred care environments. However, research shows that this focus may have unintended consequences for healthcare staff. Designs that do not...

Semantic Flowers for Good-for-Games and Deterministic Automata

We present an innovative approach for capturing the complexity of ω-regular languages using the concept of flowers. This semantic tool combines two syntax-based definitions, namely the Mostowski hierarchy of word languages and syntactic flowers. The former is based on deterministic parity automata with a limited number of priorities, while the latter simplifies deterministic parity automata by reducing the number of priorities used, without altering their structure. Synthesising these two approaches yields a semantic concept of flowers, which offers a more effective way of dealing with the complexity of ω-regular languages. This letter provides a comprehensive definition of semantic flowers and shows that it captures the complexity of ω-regular languages. We also show that this natural concept yields simple proofs of the expressive power of good-for-games automata.

Insights into Phakopsora pachyrhizi Effector-Effector Interactions.

The multifaceted role of pathogen-encoded effectors in plant-pathogen interactions is complex and not fully understood. Effectors operate within intricate host environments, interacting with host proteins and other effectors to modulate virulence. The complex interplay between effectors raises the concept of metaeffectors, wherein some effectors regulate the activity of others. While previous research has demonstrated the importance of effector repertoires in pathogen virulence, only a limited number of studies have investigated the interactions between these effectors. This study explores the interactions among Phakopsora pachyrhizi effector candidates (PpECs). P.pachyrhizi haustorial transcriptome analysis identified a collection of predicted PpECs. Among these, PpEC23 was found to interact with PpEC48, prompting further exploration into their potential interaction with other effectors. Here, we utilized a yeast two-hybrid screen to explore protein-protein interactions between PpECs. A split-luciferase complementation assay also demonstrated that these interactions could occur within soybean cells. Interestingly, PpEC48 displayed the ability to interact with several small cysteine-rich proteins (SCRPs), suggesting its affinity for this specific class of effectors. We show that these interactions involve a histidine-rich domain within PpEC48, emphasizing the significance of structural motifs in mediating effector interactions. The unique nature of PpEC48, showing no sequence matches in other organisms, suggests its relatively recent evolution and potential orphan gene status. Our work reveals insights into the intricate network of interactions among P. pachyrhizi effector-effector interactions. [Formula: see text] Copyright © 2024 The Author(s). This is an open access article distributed under the CC BY 4.0 International license.

Correlation between endometriosis and migraine features: Results from a prospective case-control study.

Endometriosis and migraine frequently coexist, but only a limited number of studies have focused on their mutual association. The aim of our study was to investigate, in untreated women with comorbid endometriosis/adenomyosis and migraine, the correlation between headache features and endometriotic subtypes and their possible relationship with pain severity and disease disability. Fifty women affected by endometriosis/adenomyosis and migraine matched (1:2) with 100 patients with endometriosis alone and 100 patients with only migraine were recruited and underwent pelvic ultrasound imaging and neurological examination. Severe adenomyosis, posterior and anterior deep infiltrating endometriosis (p = 0.027, p = 0.0031 and p = 0.029, respectively) occurred more frequently in women with migraine. Dysmenorrhea was the most commonly reported symptom in women with endometriosis and migraine and the mean VAS scores of all typical endometriotic symptoms were significantly higher in the presence of comorbidity. Women with both migraine and endometriosis reported significant higher pain intensity (p = 0.004), higher monthly migraine days (p = 0.042) and increased HIT 6-scores (p = 0.01), compared with those without endometriosis. Our results demonstrated that the co-occurrence of migraine in untreated women with endometriosis is associated with more severe gynecological infiltrations and correlated with increased pain intensity and disease disability.Trial Registration: Protocol number 119/21.

A Two-Phase Approach for Reliability-Redundancy Optimization of a Communication Satellite

The development and launch of communication satellite projects pose significant challenges and costs. The expenses can range from several hundred million dollars, contingent on factors such as mission objectives, satellite system size and complexity including the launch vehicle, and ground infrastructure. Satellites must be designed to withstand harsh conditions in space, such as the extreme temperatures, radiation, and other hazards, while delivering reliable communication services to its users. However, once a satellite is launched, physical maintenance interventions become infeasible in the event of technical problems. Thus, reliability is a critical aspect for these expensive systems. This study aims to minimize the cost of a high-tech communication satellite by addressing design considerations that meet customer reliability requirements without exceeding power and redundant equipment limits. To achieve this goal, we propose an integer non-linear programming model in this research. To solve the satellite design problem, we adopt a two-stage solution approach. Conventional industrial practices in satellite design often involve iterative attempts to determine the redundancy level of onboard units based on customer reliability requirements. These processes rely heavily on the experience of design engineers who evaluate a limited number of alternatives to determine the number of redundant units, resulting in sub-optimal outcomes. In contrast, our proposed approach systematically handles the problem and yields optimal results. Our findings demonstrate that the proposed two-phase approach can achieve optimal redundancy levels within seconds.

Commodity risk assessment of plants of 12 selected Prunus species from Moldova.

The European Commission requested the EFSA Panel on Plant Health to prepare and deliver risk assessments for commodities listed in Commission Implementing Regulation (EU) 2018/2019 as 'High-risk plants, plant products and other objects'. This Scientific Opinion covers plant health risks posed by defoliated 1- or 2-year old bare root plants for planting (grafted or not) of 12 Prunus species (Prunus armeniaca, P. avium, P. canescens, P. cerasifera, P. cerasus, P. davidiana, P. domestica, P. dulcis, P. fontanesiana, P. persica, P. salicina, P. tomentosa) imported from Moldova, taking into account the available scientific information, including the technical information provided by the applicant country. The evaluation identified three EU-quarantine pests, Erwinia amylovora (protected zone quarantine pest), Xiphinema rivesi non-EU populations and Xanthomonas arboricola pv. pruni (protected zone quarantine pest), which were selected for further evaluation, based on defined criteria, including their presence in the applicant country. It should be noted that there is uncertainty regarding whether all relevant pests have been identified due to a limited number of scientific publications and pest surveys in Moldova. For the three selected pests, the risk mitigation measures proposed in the technical dossier from Moldova were evaluated taking into account the possible limiting factors. For these pests, an expert judgement is given on the likelihood of pest freedom taking into consideration the risk mitigation measures acting on it, including uncertainties associated with the assessment. The degree of pest freedom varies among the pests evaluated, with Erwinia amylovora being the pest most frequently expected on the imported plants. The Expert Knowledge Elicitation indicated, with 95% certainty, that between 9823 and 10,000 bundles (comprising 10-20 plants per bundle) out of 10,000 bundles would be free from E. amylovora.

Synthetic Data Improve Survival Status Prediction Models in Early-Onset Colorectal Cancer.

In artificial intelligence-based modeling, working with a limited number of patient groups is challenging. This retrospective study aimed to evaluate whether applying synthetic data generation methods to the clinical data of small patient groups can enhance the performance of prediction models. A data set collected by the Cancer Registry Library Project from the Yonsei Cancer Center (YCC), Severance Hospital, between January 2008 and October 2020 was reviewed. Patients with colorectal cancer younger than 50 years who started their initial treatment at YCC were included. A Bayesian network-based synthesizing model was used to generate a synthetic data set, combined with the differential privacy (DP) method. A synthetic population of 5,005 was generated from a data set of 1,253 patients with 93 clinical features. The Hellinger distance and correlation difference metric were below 0.3 and 0.5, respectively, indicating no statistical difference. The overall survival by disease stage did not differ between the synthetic and original populations. Training with the synthetic data and validating with the original data showed the highest performances of 0.850, 0.836, and 0.790 for the Decision Tree, Random Forest, and XGBoost models, respectively. Comparison of synthetic data sets with different epsilon parameters from the original data sets showed improved performance >0.1%. For extremely small data sets, models using synthetic data outperformed those using only original data sets. The reidentification risk measures demonstrated that the epsilons between 0.1 and 100 fell below the baseline, indicating a preserved privacy state. The synthetic data generation approach enhances predictive modeling performance by maintaining statistical and clinical integrity, and simultaneously reduces privacy risks through the application of DP techniques.

Home range size of Tengmalm’s owl offspring during the post-fledging dependence period in Central and North Europe

A greater knowledge of the intrinsic and extrinsic factors of animal home range (HR) formation can help us to understand the fundamental biological issues underlying, for instance, movement patterns, habitat selection and survival. However, very little is known about the HRs of birds of prey fledglings, even though the post-fledging phase is recognised as crucial due to the high mortality of juvenile birds. We radio-tracked 138 Tengmalm’s owl (Aegolius funereus) fledglings from 43 broods to determine their HRs during the post-fledging dependence period and to investigate the factors affecting their sizes. The study was conducted during four breeding seasons in Czechia and two seasons in Finland. The mean fledglings’ HR size calculated according to the 95% IID Kernel Density Estimation method was 63.7 ± 43.9 ha (± SD; n = 71) during nocturnal activity and 52.0 ± 46.1 ha (n = 63) during diurnal roosting. The sizes of both nocturnal activity and diurnal roosting HRs increased with the longer individual duration of the post-fledging dependence period and also the higher rank of hatching within a brood. Diurnal roosting HRs were two times smaller in the Czech site, probably because of the very limited number of dense forest patches suitable for roosting as a legacy of the air pollution calamity in the 1970s, during which most coniferous stands died out. There was no difference in the size of nocturnal activity HR between the two study areas, although they differed markedly in terms of night length, altitude, weather, and forest age, structure and composition. This suggests that environmental factors are not decisive in determining the size of nocturnal activity HRs of Tengmalm’s owl fledglings. Since the diurnal HRs always occurred within the area of the nocturnal HRs, we suggest that conservation of the densest and preferably oldest forest stands within the areas of the study species occurrence may offer straightforward conservation tasks for protecting Tengmalm’s owl fledglings and also other species.

Navigated and individual α-peak-frequency-guided transcranial magnetic stimulation in male patients with treatment-refractory schizophrenia.

Previous electroencephalography (EEG) studies have indicated altered brain oscillatory α-band activity in schizophrenia, and treatment with repetitive transcranial magnetic stimulation (rTMS) using individualized α-frequency has shown therapeutic effects. Magnetic resonance imaging-based neuronavigation methods allow stimulation of a specific cortical region and improve targeting of rTMS; therefore, we sought to study the efficacy of navigated, individual α-peak-frequency-guided rTMS (αTMS) on treatment-refractory schizophrenia. We recruited medication-refractory male patients with schizophrenia or schizoaffective disorder in this doubleblind, sham-controlled study. We randomized patients to a 3-week course of either active αTMS or sham stimulation applied to the left dorsolateral prefrontal cortex (DLPFC). We assessed participants with the Positive and Negative Syndrome Scale (PANSS) and the Clinical Global Impression Scale (CGI) at baseline and after treatment. We conducted a follow-up assessment with the PANSS 3 months after intervention. We included 44 patients. After treatment, we observed a significantly higher PANSS total score (p = 0.029), PANSS general psychopathology score (p = 0.027) and PANSS 5-factor model cognitive-disorganized factor score (p = 0.011) in the αTMS group than the sham group. In addition, the CGI-Improvement score was significantly higher among those who received αTMS compared with sham stimulation (p = 0.048). The limited number of study participants included only male patients. Depression was not formally evaluated. Navigated αTMS to the left DLPFC reduced total, general psychopathological, and cognitive-disorganized symptoms of schizophrenia. These results provide evidence for the therapeutic efficacy of individual α-peak-frequency-guided rTMS in treatment-refractory schizophrenia. NCT01941251; ClinicalTrials.gov.

FrFT-based estimation of linear and nonlinear impairments using Vision Transformer

To comprehensively assess the conditions of an optical fiber communication system, it is essential to implement joint estimation of the following four critical impairments: nonlinear signal-to-noise ratio (SNRNL), optical signal-to-noise ratio (OSNR), chromatic dispersion (CD), and differential group delay (DGD). However, current studies only achieve identifying a limited number of impairments within a narrow range, due to a lack of high-performance computing algorithms and a unified representation of impairments. To address these challenges, we adopt time-frequency signal processing based on the fractional Fourier transform (FrFT) to achieve the unified representation of impairments, while employing a Transformer-based neural network (NN) to break through network performance limitations. To verify the effectiveness of the proposed estimation method, numerical simulations were conducted on a five-channel polarization-division-multiplexed quadrature phase shift keying (PDM-QPSK) long haul optical transmission system with the symbol rate of 50 GBaud per channel. The mean absolute error (MAE) for SNRNL, OSNR, CD, and DGD estimation is 0.091 dB, 0.058 dB, 117 ps/nm, and 0.38 ps, and the monitoring window ranges from 0−20dB, 10−30dB, 1700−51,000ps/nm, and 0−100ps, respectively. Our proposed method achieves accurate estimation of linear and nonlinear impairments over a broad range, representing a significant advancement in the field of optical performance monitoring (OPM).

Gulf Male Migration in Kerala: How do the Female Spouses Cope with It?

International male migration, where they have to leave their wives and families behind is becoming an increasingly visible trend in India in general and Kerala in particular. The scholars of international migration have produced a number of studies that research in detail about the economic implications on the household of these migrants. However, there have been a very limited number of studies that endeavored to look into the experiences of the wives of these migrants, especially within the context of India. This study attempts to bridge this gap by conducting a qualitative investigation on the effects of international migration of adult male members in the Thiruvananthapuram district of Kerala, specifically on their wives with the broader objective of unravelling the difficulties and concerns (if any) faced by these women in the physical absence of their husbands. In doing so, it also efforts to explore the continuity and changes in the discourse. Contextualized against the Indian landscape of patriarchy, the paper particularly intends to delineate the gendered experiences of these women especially with respect to the agency, autonomy, and decision making power exercised by them within familial settings. Further ahead, the research also aims to look into the nature of their relationship with their migrant spouses and the implications this has on their personal lives. Theoretically situated within the relational autonomy and intersectional frameworks of feminism, the study will base its findings on the data acquired qualitatively from the semi-structured interviews conducted with fifteen women from Thiruvananthapuram, whose husbands have migrated to Gulf countries for work.

Otel Yorumlarının Sınıflandırılmasında Makine Öğrenmesi Algoritmalarının Karşılaştırılması: Tripavdisor Yorumlarının Duygu Analizi

Sentiment analysis can help extract meaningful information from these data piles from various websites and social media and measure consumers' reactions by classifying consumers' emotions as positive, negative or neutral. The success of sentiment analysis varies according to feature selection, vector space selection and machine learning method. For this reason, determining the most successful method in sentiment analysis is still controversial and important. A limited number of studies have been conducted comparing the success of various machine learning methods in sentiment analysis of hotel reviews in English. Considering this gap, the purpose of this research is to determine the most successful machine learning algorithm for sentiment analysis of hotel reviews. For this purpose, 708 reviews for 5-star hotels in Istanbul were collected manually. Obtained data were classified as positive and negative using logistic regression, k-nearest neighbor, naive Bayes and support vector machine methods. Analysis results show that the logistic regression method was the most successful classification algorithm, with an accuracy rate of 0.92. It is followed by support vector machine (0.90), naive Bayes method (0.77) and k-nearest neighbor algorithms (0.66).

Balancing risks and rewards of alternate strategies in the seaward extent, duration and timing of fjord use in contemporary anadromy of brown trout (Salmo trutta)

BackgroundAnadromy comprises a successful life-cycle adaptation for salmonids, with marine migration providing improved feeding opportunities and thus improved growth. These rewards are balanced against costs from increased energy expenditure and mortality risk. Anthropogenic-induced environmental changes that reduce benefits and/or increase costs of migration e.g., aquaculture and hydropower, may therefore result in adaptations disfavouring anadromy. We tagged brown trout (Salmo trutta) smolts (N = 175) and veteran migrants (N = 342), from five adjacent riverine populations located in Sognefjorden, the longest Norwegian fjord-system supporting anadromous brown trout populations (209 km). Over four years, 138 acoustic telemetry receivers were deployed to track migrations of tagged individuals from freshwater and throughout Sognefjorden. Detected movements were used to fit migration models and multi-state mark-recapture models of survival and movement for each life-stage. Seaward migration distance was modelled to examine the fitness consequences from alternate migration strategies, with these models used to simulate the extent of fjord-use by individuals and accompanying growth, fecundity and survival consequences. We compared these findings with mark-recapture data collected prior to aquaculture and hydropower development.ResultsThe telemetry data revealed that the outermost-fjord region was utilised by all populations albeit by few individuals. However, historical recaptures were located at a greater distance from the river mouth (87.7 ± 70.3 km), when compared to maximum migration distances of present-day counterparts (58.6 ± 54.9 km). River of origin influenced observed migratory behaviour and differential survival was estimated for each population and life-stage. The simulations based on telemetry-data models revealed a 30% and 23% difference in survival among populations for smolts and veteran migrants, respectively. At the individual-level, a long-distance migration strategy was rewarded with enhanced fecundity. However, the main contribution to population-level fecundity was overwhelmingly derived from middle-distance migrants, due to higher mortality rates and limited numbers of long-distant migrants.ConclusionsWe conclude that present-day anadromy is precarious, but potential risk varies considerably between life-stages and populations, even within a single fjord system. Our findings suggest that selection for extended migration is under pressure, we therefore stress the importance of monitoring and management actions to secure genetic variation pertinent to preserve fitness gains of anadromy.