Frequency Variability Research Articles

What environmental and climatic factors influence multidecadal fire frequency?

AbstractFire is a key ecosystem process with more than half the world's land surface potentially subject to fire. A key aspect of fire ecology is the fire regime, with fire frequency an important component. Fire frequency appears to be increasing in some ecosystems, but decreasing in others. Such temporal and spatial variability in fire frequency highlights the importance of more effectively quantifying spatiotemporal changes in fire frequency for particular environments. We modeled changes in fire frequency over the past 40 years (1981–2020) in a 4.64 million ha area in Victoria, Australia. We quantified regional variation in the number of fires (hereafter termed fire frequency) during two 20‐year time periods (1981–2000 vs. 2001–2020), employing the Interim Biogeographic Regionalisation for Australia (IBRA), a standardized regionalization of Australia's terrestrial landscapes. We also quantified the climate and environmental factors influencing fire frequency in each IBRA subregion. Our empirical analyses revealed that fire frequency in Victoria was heterogeneous in both time and space. Wildfire frequency changed between 1981 and 2020, with the past 20 years (2001–2020) experiencing a substantially greater number of fires relative to the 20 years prior (1981–2000). Changes in fire frequency were not spatially uniform, with increases more pronounced in some IBRA subregions than others. Climate and topographic factors influenced the frequency of wildfires, but their effects manifested differently in different IBRA subregions. For example, fire frequency was associated with increasing rainfall deficit deviation in four IBRA subregions, but an opposite trend characterized two others. Associations between fire frequency and increasing temperature deviation also varied from negative to positive across subregions. We also found evidence of elevation, slope, and aspect effects, but these too varied between IBRA subregions. The complex spatiotemporal changes in fire frequency quantified in this study, and the complex between‐region differences in the factors associated with the number of fires, have major implications for biodiversity conservation, resource availability (e.g., timber yields), and ecosystem integrity. In ecosystems subjected to repeated fires at short intervals, new rapid detection and swift suppression technologies may be required to reduce the risks of ecosystem collapse as high‐severity wildfires increase in frequency.

Customer segmentation with RFM models and demographic variable using DBSCAN algorithm

The aims of this research was to identify prospective customers by conducting customer segmentation based on recency, frequency, monetary (RFM) values and demographic variables. The step were selected the data and normalized. The normalized data were clustered using the density based spatial clustering of applications with noise (DBSCAN) algorithm. The k-dist graph was utilized with RStudio tools to identify the best values for epsilon and MinPts. The outcome of utilizing epsilon 0.06 and MinPts 3 was the identification of 5 clusters and 31 data points considered as noise, resulting in a silhouette index (SI) value of 0.4222. Based on the average RFM values, cluster 1 was categorized as prospective customers, while clusters 2, 3, 4, and 5 were designated as loyal customers. Furthermore, according to demographic analysis, the majority of customers are between the ages of 35 to 45, female, married, and housewives. Women, groceries, such as rice and cooking oil, were the most popular products. Besides, the customers were mostly lecturers and lived in Pekanbaru. This was compatible with the customer target of people from upper middle class, such as lecturers, and with the location of the mart as well, which was near a campus.

Comparative Analysis Of Digital Or Print Book Reading References Among Journalism Students

This research is related to the preference for reading printed books with digital books by UIN Jakarta Journalism Study Program students. The purpose of this research is to find out the reading preferences of UIN Jakarta students and find out the advantages and disadvantages of reading printed or physical books. The method used in this research is a quantitative approach method with a descriptive research type, this method uses frequency and percentage variables. This study concludes that UIN Jakarta Journalism Study Program students prefer to read physical books with various advantages of the physical book itself compared to reading digital books which still have shortcomings in quality and convenience for readers

Progress Toward Transition Edge Sensor Arrays With On-Chip Thermal Stabilization

Electrothermal feedback in a transition edge sensor (TES) suppresses thermal fluctuations in the TES and well-thermally coupled regions in proximity. We have designed a heavily metallized, leg-isolated membrane with a TES which serves as a thermal isolation stage that can be lithographically integrated with other devices, for example, a suitably designed TES detector. Through modeling, fabrication, and test of prototype devices, we plan to examine the utility of stabilizing this guard stage to limit low frequency variability in the sensor response. In one implementation, a leg-isolated TES bolometer of higher superconducting transition temperature ( <italic xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">T_c</i> ) is encircled by a second membrane region which is metallized and thermally stabilized by a second, lower- <italic xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">T_c</i> TES. We present fabrication results on the dual- <italic xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">T_c</i> device and explore varied heat capacity of the thermal stability stage in the single-pixel design. We then evaluate the use of this stage for multiple pixel arrangements and investigate the criteria for stabilizing such a device.

The adverse impact of headway variability on bus transit ridership: Evidence from Bengaluru, India

This study examines the impact of bus service headway variability on bus transit ridership using direct demand models at different levels of spatial aggregation – route level and stop-route level – using transit demand and supply data from the city of Bengaluru, India. In addition, auxiliary models are developed to understand the determinants of service frequency and headway variability and to address the endogeneity of these service characteristics in the demand models. This is perhaps the first study in the public transit literature to compare and contrast the endogeneity and non-linearity effects of service frequency and headway variability in transit demand models using both a conceptual framework and empirical evidence from a large transit system. The empirical results offer evidence that variability in headways adversely impacts transit ridership and passenger-kilometres. The strength of the adverse effect increases with increasing variability. On the other hand, the influence of service frequency decreases with increasing frequency. Furthermore, it is shown conceptually and demonstrated empirically that ignoring the endogeneity of service variability results in an underestimation of its adverse effect on transit demand. On the other hand, the empirical results suggest that ignoring the endogeneity of service frequency would result in an overestimation of its beneficial effect. An important takeaway from these results and additional policy simulations is that transit agencies can potentially gain greater ridership and revenue by reducing headway variability rather than simply allocation more buses and crew to high-frequency routes.

Multi-proxy reconstruction of climate changes in the Lower St. Lawrence Estuary, Canada, during the Middle and Late-Holocene

The micropaleontological and palynological content, and geochemical and isotopic composition of a marine sediment core collected off Pointe-des-Monts in eastern Québec, Canada, reveal regional palaeoclimatic and paleoceanographic conditions in the Lower St. Lawrence Estuary over the last ~8200 years. The pollen and spore content allows comparison with the terrestrial palynostratigraphy, whereas dinoflagellate cysts and benthic foraminifera are used to reconstruct sea-surface conditions and bottom water properties, respectively. The dinocyst-based reconstructions indicate shifts between estuarine and oceanic conditions with important changes in sea-surface temperature, salinity, and primary productivity. Both the dinocyst assemblages and the quantitative sea-surface estimates highlight a distinct transition at ca. 4200 cal years BP. It is notably marked by a change towards higher salinity, which suggests reduced freshwater discharge, hence lower precipitation in the watershed, during the Late-Holocene. The isotopic composition (δ18O and δ13C) and assemblages of the benthic foraminifera indicate centennial to millennial frequency variability of bottom water properties, over a general trend towards decreasing temperatures and increasing ventilation from the beginning of the Middle Holocene until the last century. Since then, reverse trends with abrupt warming and decreasing dissolved oxygen content in bottom water have been observed.

Analysis of the Ionospheric Response to Sudden Stratospheric Warming and Geomagnetic Forcing over Europe during February and March 2023

A study of the behavior of the main characteristics of the ionosphere over Europe during the 26–28 February 2023 ionospheric storm was carried out in this present work. The additional influence of sudden stratospheric warming on the ionosphere was considered. The behavior of the critical frequency of the ionosphere foF2 (characterizing the maximum electron density), the peak height of the F2-layer (hmF2), and Total Electron Content (TEC) were investigated through their relative deviations from the quiet conditions. The behavior of the TEC over Europe showed the geographic latitudinal dependence of the response. The variability in the ionospheric critical frequency was represented by the data of 10 ionospheric stations for vertical sounding located in two groups: (i) near the prime meridian and (ii) near the 25° E meridian. Some differences were found in the response compared to the TEC response, which was explained by the different responses of the top maximum region and bottom maximum region. The peak height of the F2 layer varied strongly during the storm, which was due to the forced drift of ionospheric plasma induced by additional electric fields. The present detailed analysis of the ionospheric response shows that the considered storm exhibited characteristic features inherent in the winter season but with some manifestations of reactions in equinox conditions.

The Effect of Heart Rate Variability Biofeedback on Basketball Performance Tests.

The purpose of this study is to investigate the effects of 10-week heart rate variability biofeedback training on basketball skills, free throws, and heart rate variability parameters. Twenty-four basketball players (experimental, n = 12 and control, n = 12) aged 18-24 years volunteered to participate in this study. The experimental group participated in a 10-week heart rate variability biofeedback and basketball training program, while the control group only participated in the 10-week basketball training session. Basketball free-throw performance, basketball skills, and heart rate variability tests were conducted on the experimental and control groups before and after the 10-week intervention. Consequently, we discovered that basketball free-throw performance, breathing frequency, and heart rate variability parameters, which reflect vagal modulation of parasympathetic activity, improved in participants who underwent the 10-week heart rate variability biofeedback and basketball training, and not in those who took basketball training only. Our findings propose that heart rate variability biofeedback, alongside basketball workouts, can contribute to better basketball free-throw performance potentially through improved autonomic nervous system functioning.

Effective bowel management in spinal cord injury during inpatient rehabilitation: data from the Dutch spinal cord injury database.

Retrospective Observational Study. To describe bowel management in individuals with a recently acquired spinal cord injury (SCI) both at admittance and discharge from first inpatient rehabilitation, and to determine factors that contribute to effective bowel management (EBM) at discharge. Specialized rehabilitation centers in the Netherlands. Data from the Dutch Spinal Cord Injury Database (DSCID) collected between 2015 and 2019 was used. EBM was defined by the variables of stool frequency and fecal incontinence. After univariate analysis, a multivariate regression analysis was conducted. Of 1,210 participants, 818 (68%) did not have EBM at admittance. At discharge, 308 (38%) did still not have EBM (in total 33% of all participants). The odds of having EBM at discharge was 2.82 times higher for participants with ASIA Impairment Scale (AIS) D compared to those with AIS-A (95% CI: 1.38-5.78). Participants with non-traumatic SCI had higher odds of having EBM than those with traumatic SCI (OR: 0.59, 95% CI 0.38-0.91). Use of suppositories, small enema, medication influencing bowel function, and oral laxatives at admittance did not influence EBM significantly at discharge. Bowel management improves during first inpatient rehabilitation. However, realizing EBM after a recently acquired SCI is a challenge. This endorses the importance of bowel management during inpatient rehabilitation, especially for people with AIS-A and non-traumatic etiology.

Sensitivity simulation of sea surface temperature variability in coastal waters off East Africa in relation to the Indian Ocean Dipole

East African coastal waters in the tropical western Indian Ocean experience strong seasonality which varies yearly, leading to the establishment of a prominent interannual Indian Ocean Dipole (IOD). This has a significant influence on regional and global socio-economic, climatic and human development. Sea surface temperature (SST) variability in these waters and its association with ocean–atmosphere feedbacks and internal subsurface ocean dynamics in relation to the IOD is the subject of this study. The research used reference simulation accompanied with sensitivity simulations with forcings from higher frequency variabilities against climatological signals of ocean–atmosphere or internal subsurface ocean dynamics from 1980 to 2007. Wind forcing with higher-frequency variabilities was applied in all simulations. Cooling and warming during pure and positive IOD events leading El Niño events in the region is caused by a combination of both surface heat fluxes associated with ocean–atmosphere feedbacks, and internal subsurface ocean dynamics, from July and peaking in August and October, respectively. Such processes also dominate the warming (cooling) in the region during pure El Niño (La Niña) events from July to December (July to October) where the SST patterns extend southwards. The warmest (coolest) SST anomalies during positive (negative) IOD events co-occurring with El Niño (La Niña) events stay longer than other events, being characterised by bimodal peaking in August and December. Such SST patterns are significantly forced with ocean–atmosphere feedbacks that might be associated with Walker circulation driving links between the Indian and Pacific oceans; however, the peaking in August might be enhanced by small ocean dynamics off the Somali coast, probably owing to the existing upwelling systems during these conditions.

Voice Improvement After Essential Tremor Treatment via Focused Ultrasound and Deep Brain Stimulation.

The primary objective of this study was to determine whether two neurosurgical procedures, deep brain stimulation (DBS) and focused ultrasound (FUS), to treat essential tremor (ET) of the upper limb also reduce vocal tremor (VT) in patients with comorbid dysphonia. Twelve patients with ET and concomitant VT scheduled for neurosurgical intervention (FUS or DBS) or returning for follow-up after DBS implantation were assessed. FUS patients were assessed pre- and post-intervention and DBS patients were assessed with the electrodes turned on and off post-implantation. Three voice recordings of a sustained /a/ were obtained for each participant condition. Percent fundamental frequency variability (FFV) was calculated for each recorded sustained vowel. Additionally, blinded expert perceptual VT rating (VTR) was performed to assess subjective changes in tremors. Of the 12 patients, seven underwent unilateral FUS, and five underwent bilateral DBS. Mean FFV without neurosurgical intervention was 18.3%, SD = 7.8 and with neurosurgical intervention was 6.3%, SD = 3.0 (t (70) =8.7, p < 0.001). Mean FFV decreased in the FUS cohort from 22.0%, SD = 7.1 pre-ablation to 6.7%, SD = 2.4 post-ablation (t (40) = 7.7, p < 0.001). Mean FFV also decreased in the DBS cohort from 15.7%, SD = 7.0 to 6.0%, SD = 3.3 when stimulation was turned on (t (28)=5.7 p < 0.001). In the FUS group, mean VTR decreased from 4.0 to 1.4 post-ablation (Z = 7.8, p < 0.001). In the DBS group, mean VTR decreased from 3.3 to 2.1 with stimulation (Z = 4.1, p < 0.001). Neurosurgical interventions for ET (bilateral DBS and unilateral FUS) demonstrate acoustic and perceptual benefits for VT. 4 Laryngoscope, 134:367-373, 2024.

Ergonomic risk assessment during massage among physiotherapists: Introduction of generic postures notion.

Musculoskeletal disorders are prevalent among physiotherapists. They perform many repetitive tasks in awkward postures that require a high muscle load. This issue was often addressed through subjective analysis (questionnaire) but rarely using postural evaluation combined with an ergonomic assessment. The aim of this article was to decompose draining lymphatic massage performed by physiotherapists in generic postures (GP) to quickly assess the musculoskeletal disorder risk. Based on numeric video recorded in frontal and sagittal planes, 3360 postures were defined from 20-minutes lymphatic drainage massage performed by 7 physiotherapists over a period of 6 months. A hierarchical cluster analysis was applied to define the GP. Seven GP were identified, which were described by their average joint angles, variability and relative frequency. GP6, GP4 and GP2 had the highest frequencies (17.6%, 16.9% and 16.8% respectively). Trunk and neck were essentially flexed (neck: 17.0±10.0° for GP1; trunk: 20.4±8.7° for GP4). Shoulder flexion and abduction ranged from 15° (GP7) to 60° (GP4). Mean and variability of RULA score completed the analysis. The highest scores were computed for GP2 and GP3 (respectively 5.5±1.3 and 5.8±1.2, p < 0.05). GP4 had the lowest (4.0±1.1, p < 0.05). The results suggest that massages have to be monitored. Attention should be paid to the postures used to prevent the occurrence of MSDs. The massages could be described as a combination of generic posture for a rapid ergonomic assessment.

Predicting emergency department visits and hospitalizations for patients with heart failure in home healthcare using a time series risk model.

Little is known about proactive risk assessment concerning emergency department (ED) visits and hospitalizations in patients with heart failure (HF) who receive home healthcare (HHC) services. This study developed a time series risk model for predicting ED visits and hospitalizations in patients with HF using longitudinal electronic health record data. We also explored which data sources yield the best-performing models over various time windows. We used data collected from 9362 patients from a large HHC agency. We iteratively developed risk models using both structured (eg, standard assessment tools, vital signs, visit characteristics) and unstructured data (eg, clinical notes). Seven specific sets of variables included: (1) the Outcome and Assessment Information Set, (2) vital signs, (3) visit characteristics, (4) rule-based natural language processing-derived variables, (5) term frequency-inverse document frequency variables, (6) Bio-Clinical Bidirectional Encoder Representations from Transformers variables, and (7) topic modeling. Risk models were developed for 18 time windows (1-15, 30, 45, and 60days) before an ED visit or hospitalization. Risk prediction performances were compared using recall, precision, accuracy, F1, and area under the receiver operating curve (AUC). The best-performing model was built using a combination of all 7 sets of variables and the time window of 4days before an ED visit or hospitalization (AUC = 0.89 and F1 = 0.69). This prediction model suggests that HHC clinicians can identify patients with HF at risk for visiting the ED or hospitalization within 4days before the event, allowing for earlier targeted interventions.

Of the new opportunity of solving the Ambartsumian’s functional equation in the theory of radiative transfer

A new approach to solving of the Ambartsumian’s functional equation is presented. Its application is illustrated on the two classical cases: a) in the case of a plane-parallel semi-infinite medium with monochromatic anisotropic scattering and b) the simple one-dimensional problem of diffuse reflection of radiation from the scattering-absorbing semi-infinite medium in the case of the general law of redistribution of radiation by frequencies. The desired: a) azimuthal harmonics of reflection function dependent on two angular variables are explicitly expressed through the according eigenfunctions of one angle variable and b) diffuse reflection function of two frequency variables also expressed through a system of according eigenfunctions which have only one frequency variable. This does not require the use of any simplifying assumptions or special decompositions of the characteristics of elementary act of scattering: a) of scattering indicatrix and b) of the redistribution function of radiation by frequencies.

Resistance training prescription for muscle strength and hypertrophy in healthy adults: a systematic review and Bayesian network meta-analysis

ObjectiveTo determine how distinct combinations of resistance training prescription (RTx) variables (load, sets and frequency) affect muscle strength and hypertrophy.Data sourcesMEDLINE, Embase, Emcare, SPORTDiscus, CINAHL, and Web of Science were...

Sex differences concerning the effects of ankle muscle fatigue on static postural control and spinal proprioceptive input at the ankle.

The main aim of this study was to determine sex differences in postural control changes with ankle muscle fatigue during a standing forward leaning (FL) task under different vision conditions. The secondary aim was to examine sex differences in the effect of fatigue on soleus (SOL) H-reflex amplitude, a measure of motoneuron excitability with activation of Ia afferents. Fifteen healthy young adult males (mean age: 28.0 years) and 16 healthy young adult females (mean age: 26.1 years) were asked to perform four consecutive FL tasks [30 s; two with eyes open (EO) and two with eyes closed (EC)] before, and immediately following a fatiguing exercise consisting of alternating ankle plantarflexion (6 s) and dorsiflexion (2 s) maximal isometric contractions, and at 5 and 10 min of recovery. Center of pressure (COP) sway variables (mean position, standard deviation, ellipse area, average velocity, and frequency), an ankle co-contraction index, and a ratio of SOL H-reflex to the maximum amplitude of the compound muscle action potential (M-max) were obtained during the FL tasks. A rating of perceived fatigue (RPF) was also documented at the different time points. Time to task failure (reduction of 50% in maximal voluntary isometric contraction torque of ankle plantar flexors) and the increase in RPF value were not significantly different between males and females. Both sex groups showed similar and significant increases (p < 0.05) in mean COP sway velocity with no significant changes in co-contraction indices. No significant effects of fatigue and related interactions were found for SOL H/M-max ratio. The absence of a significant sex difference in postural control change (sway and co-contraction) with fatigue could be explained by similar perceived (RPF) and performance fatigability (exercise duration) between males and females in the present study. Fatigue did not lead to significant changes in SOL spinal motoneuron excitability with activation of Ia afferents.

Regional background and donor-language fluency as predictors of Finnish loanword frequency in Finland-Swedish

Aims and objectives: This study examines fennicisms (i.e., Finnish loanwords and calques) in Finland-Swedish, a Swedish variety spoken in Finland. We investigate how fennicism frequency relates to speakers’ regional backgrounds and fluency in Finnish. Methodology: 134 participants from four regions in Finland performed a picture-naming task designed to elicit fennicisms. The participants also rated their own fluency in Finnish. Data and analysis: A regression analysis with the outcome variable of fennicism frequency and the predictors of region, fluency in Finnish, and gender was performed. Findings: Results show that speakers from the more bilingual regions of Southern Finland and Helsinki used significantly more fennicisms than speakers from Ostrobothnia or Swedish-speaking Åland. The study suggests that fluency in Finnish was a strong predictor for fennicism use, as speakers with low or moderate knowledge of Finnish used fewer fennicisms than speakers with high or native(-like) fluency. No significant effect of gender was found. Originality: While fennicisms are considered widespread in Finland-Swedish, there is little previous research on their use and distribution. Implications: The results demonstrate that while many of the fennicisms are well-established in the Finland-Swedish variety, their use is limited to certain groups and communities.

Financial well-being and life satisfaction of individuals during the Covid-19 outbreak

Purpose - This study aims to identify how factors related to financial health, financial ignorance, future prospects, emotional constructs, mental accounting, financial crisis, and household consumptions affect adult population’s financial well-being and life satisfaction in Turkey during an ongoing pandemic. Methodology - The data were collected through an online survey between May 26 and June 15, 2020. The sample of the study consisted of 1333 participants (58.7% women; 41.3% men). Descriptive statistics were calculated regarding the socio-economic variables (frequency, percentage, average, standard deviation, maximum, minimum). Then independent groups t-test analyses were conducted to compare the means of the scales by gender. Finally, Linear Regression Model were used to compare the effects of independent variables on three dependent variables (financial well-being measured as financial security/anxiety and life satisfaction). Findings- The result shows that participants were financially coping during the COVID-19 outbreak. There was a significant difference when comparing mean financial health, spending and saving scores between men and women This study concluded that financial ignorance, financial health, perceptions of the household’s future economic outlook and national economic situation, emotional constructs and gender were significantly related to financial well-being. Furthermore, financial health, financial security, perceptions of the future economic outlook of the household economic situation, mental accounting, changes in consumption, emotional constructs, gender, and marital status were predicted life satisfaction. Conclusion- The findings would be useful for policy makers to maintain the parallel expansion of financial, psychological and welfare measures to improve people’s financial well-being and life satisfaction and to strengthen the subjective well-being of individuals to fight against COVID-19. This research will help government and policymakers to maintain their economic and psychological policies and measures to provide relief to individuals during this current and post COVID-19 recovery knowing the psychological and financial situation of the general public. Keywords: Financial health, financial ignorance, financial well-being, financial anxiety, financial security, life satisfaction. JEL Codes: A14, D1, D9

Deep learning on mixed frequency data

AbstractIn deep learning, it is common to encounter data observed at different frequencies. Mixed data sampling (MIDAS) is an efficient technique for handling mixed frequency data, where a high frequency predictor is converted into a set of low frequency variables using the frequency alignment approach and parametric function constraints. This efficiently prevents the proliferation of parameters, ensuring the consistency of data frequency. We introduce the MIDAS technique into the deep learning architecture and develop a novel deep learning‐MIDAS (DL‐MIDAS) model, which enables to conduct deep learning on raw mixed frequency data directly. Its efficacy is then illustrated through extensive Monte Carlo simulations and a real‐world application. The simulation experiments show that the DL‐MIDAS model is able to explore nonlinear patterns in mixed frequency data and achieves more stable and accurate prediction results than several competing models, such as the artificial neural network for mixed frequency data (ANN‐MIDAS), long short‐term memory (LSTM), and MIDAS regressions. Additionally, the real‐world application of predicting the inflation rate of China also confirms the strength of DL‐MIDAS. The model can exploit high frequency information contained in financial market to produce timely and accurate prediction results on the inflation rate.

A population-based study of the salivary prevalence of Porphyromonas gingivalis and Aggregatibacter actinomycetemcomitans in Saudi Arabian adults with chronic periodontitis

AimsThis study was designed to investigate the incidence of subgingival Porphyromonas gingivalis and Aggregatibacter actinomycetemcomitans infections and their relationship with genetic variability in Saudi Arabian adults with chronic periodontitis and to evaluate the correlation between infection frequency and other variables. MethodsMultiplex polymerase chain reaction (PCR) assays were developed to detect P. gingivalis 16 ​S rDNA, fimbria (fimA), and collagenase (prtC) genes, as well as the A. actinomycetemcomitans 16 ​S rDNA, leukotoxin (lktA), and fimbria-associated protein (fap) genes in saliva samples from 50 patients with periodontitis and 51 healthy subjects. ResultsThe incidence of both P. gingivalis and A. actinomycetemcomitans infections was higher (72% and 14%) in the “Periodontal disease” group than in the healthy subjects (P ​< ​0.001). The P. gingivalis 16 ​S rDNA, fimA, and prtC genes were detected in 43.56%, 61.36%, and 84.09% of saliva samples, respectively, while A. actinomycetemcomitans 16 ​S rDNA, lktA, and fap genes were detected in 6.93%, 71.43%, and 0%, respectively. P. gingivalis strains with the fimA+/prtC ​+ ​genotype were found in 61.11% and 25% of chronic periodontitis patients and healthy subjects, respectively. By comparison, A. actinomycetemcomitans strains with the lktA+ ​genotype were found in 71.43% of chronic periodontitis patients. ConclusionInfection with fimA+ and prtC+ ​P. gingivalis or lktA+ ​A. actinomycetemcomitans was correlated with periodontal disease occurrence in Saudi adults. Nevertheless, A. actinomycetemcomitans lktA and P. gingivalis fimA and prtC are closely linked to periodontal destruction, whereas A. actinomycetemcomitans fap is not.