Individual Variation Research Articles

Demonstratives in heritage Greek, Russian, and Turkish in Germany and the United States

Aims and Objectives: This study investigates the use of definite noun phrases involving demonstratives in adolescent and adult monolingually raised and heritage speakers of Greek, Russian, and Turkish with the following research questions: (1) Do heritage speakers of Greek, Russian, and Turkish align with monolingually raised speakers regarding the production of demonstratives? and (2) Do mode and register affect the use of demonstratives? Methodology: We conducted a corpus study on production data of heritage speakers of Greek, Russian, and Turkish residing in the United States and Germany and the respective monolingually raised speakers in Greece, Russia, and Turkey. The majority languages of the heritage speakers were German or English, respectively. Data were elicited in two distinct registers (formal vs informal) and in two distinct modes (spoken vs written). Participants were asked to narrate what happened in a short video showing a fictional minor car accident. Analysis: Oral and written narrations were annotated and analyzed using generalized linear mixed-effects regression modeling on the use of demonstratives by heritage and monolingually raised speakers accounting for individual variation, country of elicitation, mode, and register. Findings: The results show that heritage and monolingually raised speakers of Greek, Russian, and Turkish converge in their use of demonstratives. Also, mode and/or register significantly affect the production of definite noun phrases with demonstratives across all speaker groups. Originality: This is the first cross-linguistically comparable large-scale corpus study with ecologically valid production data of definite noun phrases with demonstratives in bilinguals. Significance: The study contributes to understanding the use of demonstratives in heritage and monolingual Greek, Russian, and Turkish. It provides insights into the use of demonstratives in languages with different determiner systems and the impact of mode and/or register, which seems to be pronounced roughly similarly across these languages.

Airborne SARS-CoV-2 RNA detected during deliveries with unmasked patients

Healthcare workers in obstetric clinics may be exposed to airborne SARS-CoV-2 when treating patients with COVID-19. In this study, performed during the midst of the pandemic, air samples were collected in delivery rooms during childbirth and analysed for SARS-CoV-2 RNA content. Six of 28 samples collected inside delivery rooms were positive for SARS-CoV-2, but none in anterooms or corridors. Five of the six positive samples were from the same occasion. This indicates that some patients could be major sources of exhaled virus, although the individual variation is large, and it is thus difficult to predict the risk of infection.

Estimation of winter wheat LAI based on color indices and texture features of RGB images taken by UAV.

Leaf area index (LAI) is an important indicator for assessing plant growth and development, and is also closely related to photosynthesis in plants. The realization of rapid accurate estimation of crop LAI plays an important role in guiding farmland production. In study, the UAV-RGB technology was used to estimate LAI based on 65 winter wheat varieties at different fertility periods, the wheat varieties including farm varieties, main cultivars, new lines, core germplasm and foreign varieties. Color indices (CIs) and texture features were extracted from RGB images to determine their quantitative link to LAI. The results revealed that among the extracted image features, LAI exhibited a significant positive correlation with CIs (r = 0.801), whereas there was a significant negative correlation with texture features (r = -0.783). Furthermore, the visible atmospheric resistance index, the green-red vegetation index, the modified green-red vegetation index in the CIs, and the mean in the texture features demonstrated a strong correlation with the LAI with r > 0.8. With reference to the model input variables, the backpropagation neural network (BPNN) model of LAI based on the CIs and texture features (R2 = 0.730, RMSE = 0.691, RPD = 1.927) outperformed other models constructed by individual variables. This study offers a theoretical basis and technical reference for precise monitor on winter wheat LAI based on consumer-level UAVs. The BPNN model, incorporating CIs and texture features, proved to be superior in estimating LAI, and offered a reliable method for monitoring the growth of winter wheat. © 2024 Society of Chemical Industry.

Development and validation of a novel vault prediction formula based on structural parameters of the anterior and posterior chambers

BackgroundAccurate prediction of postoperative vault in implantable collamer lens (ICL) implantation is crucial; however, current formulas often fail to account for individual anatomical variations, leading to suboptimal visual outcomes and necessitating improved predictive models. We aimed to verify the prediction accuracy of our new predictive model for vaulting based on anterior and posterior chamber structural parameters.MethodsThis retrospective observational study included 137 patients (240 eyes) who previously underwent ICL surgery. Patients were randomly divided into the model establishment (192 eyes) or validation (48 eyes) groups. Preoperative measurements of the anterior and posterior chamber structures were obtained using Pentacam, CASIA2 anterior segment optical coherence tomography (AS-OCT), ultrasound biomicroscopy, and other devices. Stepwise multiple linear regression analysis was used to evaluate the relationship between the vault and each variable (WL formula). The Friedman test was performed for the vaulting prediction results of the WL, NK (Ver. 3), and KS formulas (Ver. 4) in CASIA2 AS-OCT, as well as the Zhu formula and vault measurements. The proportions of prediction error within ± 250 μm per formula were compared.ResultsThe predicted vault values of the WL, NK, KS, and Zhu formulas and vault measurements were 668.74 ± 162.12, 650.85 ± 248.47, 546.56 ± 128.99, 486.56 ± 210.76, and 716.06 ± 233.84 μm, respectively, with a significant difference (χ2 = 69.883, P = 0.000). Significant differences were also found between the measured vault value and Zhu formula, measured vault value and KS formula, WL formula and Zhu formula, WL formula and KS formula, NK formula and KS formula, and NK formula and Zhu formula (P < 0.001) but not between other groups. The proportions of prediction error within ± 250 μm per formula were as follows: WL formula (81.3%) > NK formula (70.8%) > KS formula (66.7%) > Zhu formula (54.2%).ConclusionsThe WL formula, which considers the complexity of the anterior and posterior chamber structures, demonstrates greater calculation accuracy, compared with the KS (Ver. 4) and Zhu formulas. The proportion of absolute prediction error ≤ 250 μm is higher with the WL formula than with the NK formula (ver. 3). This enhanced predictive capability can improve ICL sizing decisions, thereby increasing the safety and efficacy of ICL implantation surgeries.

Neighbourhood effects on herbivory damage and chemical profiles in short-rotation coppice willows and their hybrids

Short rotation coppices (SRCs) represent an important source of biomass. Since they are grown in various mixtures, SRCs represent an excellent opportunity for assessing the effects of local plant neighbourhoods on their performance. We used a common garden experiment consisting of plots that varied in genotype diversity of SRC willows to test for the effects of chemical traits of individual plants and chemical variation in the plots where they grew on insect herbivory. We also explored whether the composition of willows planted in a plot affected their chemistry. To do this, we performed untargeted metabolomics and quantified various chemical traits related to the total set of metabolites we detected, flavonoids, and salicinoids in four willow genotypes. We measured the leaf herbivory that the plants suffered. The genotypes differed in most chemical traits, yet we found only limited effects of individual traits on herbivory damage. Instead, herbivory damage was positively correlated with structural variation in salicinoids in a plot. When analysing the effects of plot chemical variation on herbivory damage separately for each genotype, we found both positive and negative correlations between the two, suggesting both associational resistance and susceptibility. Finally, we also observed a significant effect of the interaction between genotype and plot composition on structural variation in plant chemistry. Overall, our results suggest that high chemical variation in mixed willow SRCs does not necessarily lower the herbivory damage, possibly due to spillover effects of insect herbivores among genotypes. Our results also show that different genotypes respond differently to plot composition in terms of herbivory damage and chemical composition, which may affect their suitability for growing in mixed stands.

DOSage of Exercise for chronic low back pain disorders (DOSE): protocol for a systematic review with dose-response network meta-analysis

Chronic low back disorders are the leading cause of direct and indirect healthcare burden globally. Exercise training improves pain intensity, mental health and physical function. However, the optimal prescription variables...

New insights into the contributions of playfulness to dealing with stress at work: Correlates of self- and peer-rated playfulness and coping strategies

Playfulness is an individual difference variable that enables people to experience and (re)frame situations of everyday life as interesting, entertaining, and/or stimulating. This definition is consistent with a structural model that includes four different playfulness facets: other-directed, lighthearted, intellectual, and whimsical playfulness. In the work context, playfulness has been shown to be related with various outcomes such as innovative behavior or intrinsic goals. We tested adult playfulness' associations with coping strategies employed at work and whether these coping strategies help to transfer the expected association between playfulness and employees' life satisfaction. Study 1 (N = 185; nursery school trainees) provides support for our hypothesis that playfulness is associated with more positive and less negative coping strategies when being confronted with general and work-specific stress. Study 2 (N = 355; employees from various working fields) confirms our results from study 1 by demonstrating that playfulness is related to adaptively coping with work stress. Further, study 2 shows that some playfulness facets were positively related to life satisfaction and that these associations were transferred by coping less negatively with work stress and, to some degree, also by utilizing positive control strategies. Overall, our findings indicate that adults' playfulness is of importance for coping with stress at work and to further explain employees’ life-satisfaction. Directions for future research on playfulness in the work place are discussed.

Mixed methods with social network analysis for networked learning

In our research we study small group interaction and meaning making in the context of a larger community of people and artifacts. Our research methodology combines social network analysis and content analysis in different ways. The primary purpose of this paper is to explore approaches and demonstrate the feasibility of mixed methods research combining network-level and content-level methods. We report our experiences from three case studies (Get Satisfaction, Canvas, r/place), which include individual variation (innovative approaches toward integration) and a common approach of “zooming in,” or shifting perspective between bird’s eye and detailed levels of interaction data during analysis (message content, dialogic structure, or visual artifact vs. patterns of users and their interactions). We show that the two sets of methods in combination can eliminate shortcomings of the separate methods used independently.

Individual dietary specialization and intraspecific morphological divergence of an endemic fish species: the case of Glanidium ribeiroi in the Iguassu ecoregion

ABSTRACT Because of the importance of information about endemic species and global biodiversity ecoregion, we tested the hypothesis that individuals of Glanidium ribeiroi (endemic species in the Iguassu ecoregion) are specialists and that this specialization decreases with increasing body size, especially concerning the size of the mouth and head, which can be limiting for the quantity and size of prey consumed by smaller individuals. Fish sampling was conducted monthly using gill nets and longlines from 2013 to 2016 in the main channel of the Iguaçu River and two tributaries. We observed the consumption of aquatic insects by smaller individuals and seeds, unidentified fish, and Decapoda by larger individuals. Individual dietary specialization was high and related to head width. The morphological traits of smaller-sized individuals were related to displacement and movement (larger peduncle), and the larger-sized individuals were related to high performance in the exploitation and prey acquisition (larger head and mouth, dorsal eyes, longer intestines). Our results highlight the importance of assessing individual variations within a population, favoring an understanding of population dynamics. In addition, morphological differences may imply differences in the use of habitat and food resources between individuals of larger and smaller body sizes and influence individual specialization.

Is Vitamin D a Crucial Molecule for Musculoskeletal and Cardiovascular Systems in Postmenopausal Women?

Vitamin D, a steroid hormone, acts via the vitamin D receptor expressed in various tissues, including bones, muscles, and the cardiovascular system and is associated with well-being of individuals and vitamin D deficiency is considered as a prevalent public health problem. Menopause is an important cornerstone for women, where the hormonal changes may lead to adverse health effects. Vitamin D deficiency during menopausal transition or in postmenopausal period may aggravate the health risks such as osteoporosis, sarcopenia, and cardiovascular diseases associated with menopause. This manuscript aims to provide a review of the complex interaction between vitamin D deficiency and the well-being of postmenopausal women, focusing on musculoskeletal and cardiovascular implications. Clinical studies highlight the importance of maintaining optimal vitamin D levels to decrease the risk of musculoskeletal disorders and cardiovascular diseases in postmenopausal women. However, conflicting findings regarding the effectiveness of vitamin D supplementation in reducing cardiovascular risk suggest the need for further research and a personalized approach for the chemical form of Vitamin D, dose, duration of deficiency, individual variations, and accompanying conditions. The use of vitamin D supplementation in well-evaluated patients is desirable, and help to optimize health status in postmenopausal women.

Salivary cortisol captures endocrine response to an acute stressor in captive female tufted capuchin monkeys (Sapajus apella).

Measuring glucocorticoids such as cortisol is a useful tool for exploring relationships among behavior, physiology, and well-being in primates. As cortisol circulates in blood, it moves into biological matrices such as hair, urine, feces, and saliva. Saliva sampling is a simple, noninvasive method to measure cortisol that can be easily implemented by training animals to voluntarily provide samples. The temporal lag between elevation of cortisol in the blood and elevation of cortisol in saliva likely varies by species and must be characterized to identify appropriate sampling regimens. In the present study we characterized the time course of cortisol changes in saliva following an acute psychological stressor in captive tufted capuchin monkeys (Sapajus apella). We trained eight free-moving female tufted capuchin monkeys to voluntarily produce clean saliva samples. We exposed them to the acute stressor of a veterinary catch net and observed behavior pre and post exposure. We collected salivary samples immediately pre exposure (0 min) and 30, 45, 60, 75, 90, and 120 min after exposure. Salivary cortisol was quantified using a Salimetrics kit. Behavioral and cortisol measures were compared within individuals to a control condition in which no stressor was presented. Capuchins showed a clear behavioral response to the stressor by demonstrating increased freezing and pacing, decreased feed foraging, nonsocial play, and scratching, and decreased willingness to provide saliva samples after stressor presentation. After stressor presentation, average salivary cortisol began to increase at 30 min and continued to increase through the 120 min sample period. There was individual variation in absolute cortisol levels, the timing of the cortisol increase, and the timing of the peak. Our results suggest that no single time-point can be reliably used to evaluate salivary cortisol response to an acute stressor across individuals, and instead we recommend the collection of a prolonged time series.

Individual variation in the emergence of anterior-to-posterior neural fates from human pluripotent stem cells

Variability between human pluripotent stem cell (hPSC) lines remains a challenge and opportunity in biomedicine. In this study, hPSC lines from multiple donors were differentiated toward neuroectoderm and mesendoderm lineages. We revealed dynamic transcriptomic patterns that delineate the emergence of these lineages, which were conserved across lines, along with individual line-specific transcriptional signatures that were invariant throughout differentiation. These transcriptomic signatures predicted an antagonism between SOX21-driven forebrain fates and retinoic acid-induced hindbrain fates. Replicate lines and paired adult tissue demonstrated the stability of these line-specific transcriptomic traits. We show that this transcriptomic variation in lineage bias had both genetic and epigenetic origins, aligned with the anterior-to-posterior structure of early mammalian development, and was present across a large collection of hPSC lines. These findings contribute to developing systematic analyses of PSCs to define the origin and consequences of variation in the early events orchestrating individual human development.

Neoadjuvant Statistical Algorithm to Predict Individual Risk of Relapse in Patients with Resected Liver Metastases from Colorectal Cancer.

(1) Background: Liver metastases (LM) are the leading cause of death in colorectal cancer (CRC) patients. Despite advancements, relapse rates remain high and current prognostic nomograms lack accuracy. Our objective is to develop an interpretable neoadjuvant algorithm based on mathematical models to accurately predict individual risk, ensuring mathematical transparency and auditability. (2) Methods: We retrospectively evaluated 86 CRC patients with LM treated with neoadjuvant systemic therapy followed by complete surgical resection. A comprehensive analysis of 155 individual patient variables was performed. Logistic regression (LR) was utilized to develop the predictive model for relapse risk through significance testing and ANOVA analysis. Due to data limitations, gradient boosting machine (GBM) and synthetic data were also used. (3) Results: The model was based on data from 74 patients (12 were excluded). After a median follow-up of 58 months, 5-year relapse-free survival (RFS) rate was 33% and 5-year overall survival (OS) rate was 60.7%. Fifteen key variables were used to train the GBM model, which showed promising accuracy (0.82), sensitivity (0.59), and specificity (0.96) in predicting relapse. Similar results were obtained when external validation was performed as well. (4) Conclusions: This model offers an alternative for predicting individual relapse risk, aiding in personalized adjuvant therapy and follow-up strategies.

Anthropometric characteristics and Somatotypes in Elite Pro Kabaddi League Players

Introduction: Kabaddi players exhibit diverse body compositions that vary by playing position. Understanding these traits provides valuable insights into their physical profiles and performance potential. The study aimed to examine the anthropometric characteristics and somatotypes of elite professional Indian Kabaddi players and to evaluate the differences in anthropometric traits between defenders and raiders. Method: Twenty male elite Kabaddi players (raiders n = 9, and defenders n = 11) part of the Haryana Steelers pre-season squad during Season-10, participated in the study. Anthropometric measurements included body mass, stature, 8 skinfold sites, 3 girths, and 2 breadths. Somatotypes, body fat percentage, fat mass, and lean body mass were calculated for each participant. Descriptive statistics were used to estimate the basic functional status of the athletes. Independent samples t test was used to test for significant differences between raiders and defenders. Results: Significant differences were found between raiders and defenders across seven out of thirty-six variables. Raiders had higher mean values for height [t (18) = 2.71, p = 0.01], leg length [t (18) = 2.20, p = 0.04], height-weight ratio [t (18) = 2.79, p = 0.01], and ectomorph component [t (18) = 2.50, p = 0.02]. In contrast, defenders had significantly higher values for supraspinale skinfolds [t (18) = -2.17, p = 0.04], arm span to height ratio [t (18) = -2.53, p = 0.02], and mesomorph component [t (18) = -2.33, p = 0.03]. The 95% confidence intervals for these differences showed substantial variability across the examined parameters. Conclusion: The study reveals anthropometric and somatotype differences between raiders and defenders in elite Indian Kabaddi players, emphasizing the need for position-specific training programs. These findings provide valuable insights into the physical attributes associated with each position, aiding coaches in optimizing player development and positional assignment while emphasizing the importance of individual variability in training programs.

Use of weather types to analyze the simultaneous abundance of ozone, PM2.5 and allergenic tree pollen: focusing on the potential impact on asthma hospitalization in Montreal, Canada

AbstractAir pollution, aeroallergens, and weather conditions can worsen health symptoms such as asthma. While studying the impact of these factors, the use of weather types (WTs) rather than individual meteorological variables (such as temperature, relative humidity, wind, cloudiness, or precipitation) is more appropriate since it is holistic and integrative. Moreover, several studies have shown that the human body responds to WTs, rather than to individual meteorological variables. In this study, the use of Sheridan’s WTs is adopted and compared with a so-called “In-House” WTs. The analysis presented here deals with the links between asthma hospitalization and the synergy among air pollution, birch tree pollen and WTs. Knowing the daily WT in a region can provide valuable information for health planning and management of asthma hospitalization, emergency visits and sub-clinical symptoms in the population. This is because air pollution and birch pollen both occur within only a few specific WTs, such as the TROWAL (trough of warm air aloft) or tropical airmasses. These specific WTs need to be more scrutinized since, in Montreal, these are often linked with higher daily mean hospitalization. The findings of this study emphasize the importance of specific WTs in determining the maximum daily concentrations of ozone, fine particles, Betula pollen concentrations and health effects such as asthma hospitalization. Moreover, the use of data filters in the analysis (for temperature and total count of hospitalization) also reveals new insights in the complex nature of asthma disease and its relationship with environmental factors.

Impact of transcranial electrical stimulation on simultaneous stereoelectroencephalography recordings: A randomized sham-controlled study

ObjectiveClinical exploitation of transcranial electrical stimulation for focal epilepsy treatment lacks quantification of the underlying neurophysiological changes. This study explores the immediate effects of transcranial alternating (tACS) and direct (tDCS) current stimulation on local and network brain activity using simultaneous stereoelectroencephalography (SEEG) recordings. MethodsPatients were randomized for personalized tACS (n = 5) or tDCS (n = 6). Active stimulation (20 min) was preceded by sham stimulation (20 min). Changes in interictal epileptiform discharges (IED), functional connectivity (FC) and power spectral density (PSD) were quantified against baseline. ResultsResults demonstrated variable responses. Spike rate decreased in 2/6 subjects following sham and tDCS, while 2/6 showed an increase. Alpha power and aperiodic PSD components generally increased during and after tDCS but decreased following tACS. FC changes varied among subjects and were detectable even during sham sessions. ConclusionsStrong variability suggests that tES does not have a univocal effect on immediate changes in IED or FC, possibly due to the single session format and challenges in affecting subcortical areas. SignificanceThis is the first study to examine intracranial FC changes during tACS and tDCS, highlighting the importance of sham comparisons and individual variability in tES response, offering valuable insights into its application for epilepsy treatment.

Crossing borders, casting votes: examining migrant electoral turnout in Chile (2012–2020)

ABSTRACT Our analysis focuses on the determinants of electoral participation among migrants, considering individual factors—gender and age—and variables from their countries of origin, such as economic, political, and institutional aspects. We specifically look at Chile, where migrants are allowed to vote in all elections after acquiring five years of permanent residency. Utilizing a comprehensive administrative census covering over 70 million voters, including 1.2 million migrants, from 2012 to 2020, our findings reveal several key patterns: Gender and age significantly influence voting behavior, with higher turnout among women and older migrants. Additionally, migrants from wealthier nations tend to vote less compared to those from poorer countries. Furthermore, the presence of compulsory voting in the origin country significantly increases participation among migrants, especially those from less democratic or non-democratic countries. This study bridges theoretical models that focus on individual variables and those that emphasize the impact of origin country characteristics on migrant electoral behavior.

Persistent carriage of subpatent Plasmodium falciparum parasites associated with clinical malaria in a low transmission area in Senegal

ObjectivesIn low malaria transmission areas, the elimination of the disease has been hampered partly by the existence of a reservoir of subpatent Plasmodium falciparum infections within communities. This reservoir, often undetected, serves as a source of parasites and contributes to ongoing transmission and clinical malaria cases. MethodsThis study, spanning a period of 9 years from June 2014 to December 2022, examined individual variations and long-term subpatent P. falciparum carriage in two matched cohorts of 44 individuals each living in Dielmo village in the Sudanian area of Senegal. Biannual blood samples, collected in June/July and December of each year, underwent P. falciparum diagnosis by quantitative polymerase chain reaction. QGIS and R analytical tools were used to map infections, assess the occurrence and clustering of subpatent and clinical P. falciparum infections, and determine the risk of infection in the vicinity of asymptomatic P. falciparum carriers. ResultsThe point frequency and long-term P. falciparum carriage were significantly higher among the quantitative polymerase chain reaction (qPCR) positive cohort compared to the negative cohort across the 16 cross-sectional surveys analyzed in this study (19.76% vs 10.99%, P-value <0.001). Asymptomatic carriage events in qPCR-positive group were 18.86 ± 1.72% and significantly greater (P-value = 0.001) than in the qPCR-negative group (11.32 ± 1.32%). The relative risk of P. falciparum infection or clinical malaria calculated with a 95% confidence interval significantly increased in the vicinity of infected individuals and was 1.44 (P-value = 0.53) and 2.64 (P-value = 0.04) when at least one individual in the direct (household) or indirect (block of households) vicinity is infected, respectively. The risk increased to 3.64 (P-value <0.001) if at least 1/5 of individuals in the indirect vicinity were P. falciparum-infected. ConclusionsThe study provides a detailed qualitative and quantitative analysis of the asymptomatic P. falciparum reservoir and its temporal and spatial dynamics within two subgroups of P. falciparum-infected and non-infected individuals in Dielmo village. It identified high-risk populations known as “hotpops” and hotspots that could be targeted by innovative interventions to accelerate the elimination of malaria in Dielmo village.

Development and validation of a prognostic model to predict birth weight: individual participant data meta-analysis

ObjectiveTo predict birth weight at various potential gestational ages of delivery based on data routinely available at the first antenatal visit.DesignIndividual participant data meta-analysis.Data sourcesIndividual participant data of four cohorts...

Individual corticosterone response to intermittent swim stress predicts a shift in economic demand for ethanol from pre-stress to post-stress in male rats.

This study investigated the relationship between stress exposure and subsequent ethanol use, focusing on individual differences among male rats. We combined operant self-administration with behavioral economics to assess how intermittent swim stress affects ethanol consumption. This approach allowed for a nuanced analysis of the transition from regular ethanol intake to stress-induced escalation in economic demand. Results showed a consistent rise in ethanol demand post-stress among subjects, irrespective of exposure to actual swim stress or a sham procedure. This increase may result from a two-week abstinence or an inherent rise in demand over time. Significantly, we identified a direct link between post-stress corticosterone levels and the demand for ethanol, considering baseline levels. This correlation was particularly pronounced when examining the shifts in both corticosterone levels and demand for ethanol post-stress. However, neither post-stress corticosterone levels nor their change over time correlated significantly with changes in ethanol demand following a forced swim test that was administered 24 h after the intermittent swim stress test. This suggests potential context-specific or stressor-specific effects. Importantly, pre-stress ethanol demand did not significantly predict the corticosterone response to stress, indicating that high ethanol-demand rats do not inherently exhibit heightened stress sensitivity. Our research brings to light the complex interplay between stress and ethanol consumption, highlighting the critical role of individual differences in this relationship. This research introduces a nuanced perspective, underscoring the need for future studies in the realm of stress and substance use to give greater consideration to individual variability.