Partial Least-squares Analysis Research Articles

Variety is the spice: The role of morphological variation of Triatoma infestans (Hemiptera, Reduviidae) at a macro-scale

Chagas disease is caused by the protozoan parasite Trypanosoma cruzi (Chagas, 1909). One of the primary vectors of T. cruzi in South America is Triatoma infestans (Klug, 1834). This triatomine species is distributed across a huge latitudinal gradient, inhabiting domiciliary , peridomiciliary , and wild environments. Its wide geographic distribution provides an excellent opportunity to study the relationships between environmental gradients and intraspecific morphological variation. In this study, we investigated variations in wing size and shape in T. infestans across six ecoregions. We aimed to address the following questions: How do wing size and shape vary on a regional scale, does morphological variation follow specific patterns along an environmental or latitudinal gradient, and what environmental factors might contribute to wing variation? Geometric morphometric methods were applied to the wings of 162 females belonging to 21 T. infestans populations, 13 from Argentina (n = 105), 5 from Bolivia (n = 42), and 3 from Paraguay (n = 15). A comparison of wing centroid size across the 21 populations showed significant differences. Canonical Variate Analysis (CVA) revealed significant differences in wing shape between the populations from Argentina, Bolivia, and Paraguay, although there was a considerable overlap, especially among the Argentinian populations. Well-structured populations were observed for the Bolivian and Paraguayan groups. Two analyses were performed to assess the association between wing size and shape, geographic and climatic variables: multiple linear regression analysis (MRA) for size and Partial Least Squares (PLS) regression for shape. The MRA showed a significant general model fit. Six temperature-related variables, one precipitation-related variable, and the latitude showed significant associations with wing size. The PLS analysis revealed a significant correlation between wing shape with latitude, longitude, temperature-related, and rainfall-related variables. Wing size and shape in T. infestans populations varied across geographic distribution. Our findings demonstrate that geographic and climatic variables significantly influence T. infestans wing morphology.

The Influence Of The Use Of Information Technology And Competence On Employee Performance At The Population And Civil Registry Service Of Pagar Alam City

This research aims to determine the influence of information technology and competency on employee performance at the Pagar Alam City Population and Civil Registry Service. The dependent variable in this research is Employee Performance (Y) and the independent variables are Information Technology (X1) and Competency (X2). The population and research sample were 50 employees at the Population and Civil Registry Service of Pagar Alam City. The data obtained were analyzed using the PLS (Partial Least Square) analysis technique via SmartPLS Software and the SPSS 26 application. Where it was partially processed using the PLS analysis technique while it was simultaneously processed using the SPSS 26 application. Based on the research results it can be concluded that: (1) Information technology positive and significant effect on employee performance; (2) Competency has a positive and significant effect on employee performance; (3) simultaneously, information technology and competence have a positive and significant effect on employee performance.

Connectome reorganization associated with temporal lobe pathology and its surgical resection.

Network neuroscience offers a unique framework to understand the organizational principles of the human brain. Despite recent progress, our understanding of how the brain is modulated by focal lesions remains incomplete. Resection of the temporal lobe is the most effective treatment to control seizures in pharmaco-resistant temporal lobe epilepsy (TLE), making this syndrome a powerful model to study lesional effects on network organization in young and middle-aged adults. Here, we assessed the downstream consequences of a focal lesion and its surgical resection on the brain's structural connectome, and explored how this reorganization relates to clinical variables at the individual patient level. We included adults with pharmaco-resistant TLE (n = 37) who underwent anterior temporal lobectomy between two imaging time points, as well as age- and sex-matched healthy controls who underwent comparable imaging (n = 31). Core to our analysis was the projection of high-dimensional structural connectome data-derived from diffusion MRI tractography from each subject-into lower-dimensional gradients. We then compared connectome gradients in patients relative to controls before surgery, tracked surgically-induced connectome reconfiguration from pre- to postoperative time points, and examined associations to patient-specific clinical and imaging phenotypes. Before surgery, individuals with TLE presented with marked connectome changes in bilateral temporo-parietal regions, reflecting an increased segregation of the ipsilateral anterior temporal lobe from the rest of the brain. Surgery-induced connectome reorganization was localized to this temporo-parietal subnetwork, but primarily involved postoperative integration of contralateral regions with the rest of the brain. Using a partial least-squares analysis, we uncovered a latent clinical-imaging signature underlying this pre- to postoperative connectome reorganization, showing that patients who displayed postoperative integration in bilateral fronto-occipital cortices also had greater preoperative ipsilateral hippocampal atrophy, lower seizure frequency, and secondarily generalized seizures. Our results bridge the effects of focal brain lesions and their surgical resections with large-scale network reorganization and inter-individual clinical variability, thus offering new avenues to examine the fundamental malleability of the human brain.

Disease evolution and organ damage accrual in patients with stable UCTD: a long-term monocentric inception cohort

ObjectivesUndifferentiated connective tissue diseases (UCTDs) are systemic autoimmune conditions that cannot be diagnosed nor classified as defined CTD; the majority maintains an undifferentiated profile (stable UCTD, sUCTD) over time. Data...

Analytical solution to partial least squares

Partial least squares (PLS) is a widely used multivariate statistical technique, which can be used in neuroimaging, process monitoring, economics, etc. Because the standard PLS is trained by nonlinear iterative partial least squares (NIPALS) algorithm, which can only obtain the numerical solution rather than the analytical solution. Therefore, it is hard for the subsequent theoretical analysis in PLS and the iterative optimization process is computationally intensive. This paper proposes an analytical solution to take the place of NIPALS. This determination meaningfully contributes to future theoretical analysis of PLS. In addition, the analytical solution demonstrates that the selection of initial vector in NIPALS does not affect the PLS training results. Moreover, the analytical solution avoids the multiple iterative calculations, so the divergence of the calculation process will be avoided and the computation burden will be reduced significantly.

The Influence of Building Quality, Strategic Location, and Price on the Decision to Purchase Subsidized Housing in the Cileungsi Area

This study aims to present a comprehensive depiction of the factors influencing the decision-making process regarding the purchase of subsidized housing, focusing specifically on variables such as building quality, strategic location, and price. The research objectives include identifying the key variables impacting the choice of acquiring subsidized housing in the Cileungsi region through a quantitative descriptive approach. Utilizing purposive sampling, the study surveyed one hundred local residents who recently acquired homes through government assistance programs. Structural Equation Modeling (SEM) employing variance-based methods or component-based structural equation modeling, specifically Partial Least Squares (PLS), was utilized for data analysis. The anticipated outcomes of this investigation are expected to contribute significantly to understanding consumer behavior in the context of subsidized housing purchases in Cileungsi. Moreover, the application of PLS analysis methods is poised to provide an in-depth comprehension of the interrelationships among variables within the tested model and furnish strategic recommendations for developers of subsidized housing and pertinent stakeholders to enhance product appeal.

Characterizing the Impact of Cyanobacterial Blooms on the Photoreactivity of Surface Waters from New York Lakes: A Combined Statewide Survey and Laboratory Investigation.

Cyanobacterial blooms introduce autochthonous dissolved organic matter (DOM) into aquatic environments, but their impact on surface water photoreactivity has not been investigated through collaborative field sampling with comparative laboratory assessments. In this work, we quantified the apparent quantum yields (Φapp,RI) of reactive intermediates (RIs), including excited triplet states of dissolved organic matter (3DOM*), singlet oxygen (1O2), and hydroxyl radicals (•OH), for whole water samples collected by citizen volunteers from more than 100 New York lakes. Multiple comparisons tests and orthogonal partial least-squares analysis identified the level of cyanobacterial chlorophyll a as a key factor in explaining the enhanced photoreactivity of whole water samples sourced from bloom-impacted lakes. Laboratory recultivation of bloom samples in bloom-free lake water demonstrated that apparent increases in Φapp,RI during cyanobacterial growth were likely driven by the production of photoreactive moieties through the heterotrophic transformation of freshly produced labile bloom exudates. Cyanobacterial proliferation also altered the energy distribution of 3DOM* and contributed to the accelerated transformation of protriptyline, a model organic micropollutant susceptible to photosensitized reactions, under simulated sunlight conditions. Overall, our study provides insights into the relationship between the photoreactivity of surface waters and the limnological characteristics and trophic state of lakes and highlights the relevance of cyanobacterial abundance in predicting the photoreactivity of bloom-impacted surface waters.

The Influence of Financial Literacy and Financial Inclusion as Women Workers' Activities and Performance at the Puri Santrian Hotel

Literacy finance followed with inclusion finance public. Inclusion finance related tightly with literacy For increase ability activity worker in use service finance. The low knowledge literacy finance somebody become reason appearance error management finances, however Lots workers who are still Not yet own knowledge good literacy. Current research accomplished the goal ie look for know exists influence (1) Literacy finance to Activity worker women , (2) Inclusion finance to Activity worker women , (3) Literacy finance on Performance, (4) Inclusion finance on Performance, (5) Activities worker woman on Performance, (6) Literacy finance with mediated by activity worker woman on Performance, and (7) Inclusion finance with mediated by activity worker woman on Performance. Study This held at the Puri Santrian Hotel in 2024 with subject study worker woman at the Puri Santrian hotel with respondents as many as 101 workers. Average results respondents For Literacy finance 4.39; Inclusion finance 4.40; Activity finance worker women 4.39 and Performance 4.49. The analysis technique researcher use Partial Least Squares (PLS) . According to results PLS analysis shows all over the hypothesis with p-value s0.05 indicates happen rejection of H o as well reception H a d. Regarding the means literacy finance influence activity finance worker woman as well as performance in a way significant . Inclusion finance in a way positive influential significant on activity finance worker women and performance. Activity finance worker woman in a way positive effect on performance with characteristic significant. In conclusion inclusion finance as well as literacy finance influence nature of performance positive as well as significant with mediated by activity finance worker woman at the Puri Santrian Hotel.

Real-Time Quantitative Evaluation of a Drug during Liposome Preparation Using a Probe-Type Raman Spectrometer.

During the manufacturing process of liposome formulations, it is considered difficult to evaluate their physicochemical properties and biological profiles due to the complexity of their structure and manufacturing process. Conventional quality evaluation is labor-intensive and time-consuming; therefore, there was a need to introduce a method that could perform in-line, real-time evaluation during the manufacturing process. In this study, Raman spectroscopy was used to monitor in real time the encapsulation of drugs into liposomes and the drug release, which are particularly important quality evaluation items. Furthermore, Raman spectroscopy combined with partial least-squares (PLS) analysis was used for quantitative drug evaluation to assess consistency with results from UV-visible spectrophotometry (UV), a common quantification method. The prepared various ciprofloxacin (CPFX) liposomes were placed in cellulose tubes, and a probe-type Raman spectrophotometer was used to monitor drug encapsulation, the removal of unencapsulated drug, and drug release characteristics in real time using a dialysis method. In the Raman spectra of the liposomes prepared by remote loading, the intensities of the CPFX-derived peaks increased upon drug encapsulation and showed a slight decrease upon removal of the unencapsulated drug. Furthermore, the peak intensity decreased more gradually during the drug release. In all Raman monitoring experiments, the discrepancy between quantified values of CPFX concentration in liposomes, as measured by Raman spectroscopy combined with partial least-squares (PLS) analysis, and those obtained through ultraviolet (UV) spectrophotometry was within 6.7%. The results revealed that the quantitative evaluation of drugs using a combination of Raman spectroscopy and PLS analysis was as accurate as the evaluation using UV spectrophotometry, which was used for comparison. These results indicate the promising potential of Raman spectroscopy as an innovative method for the quality evaluation of liposomal formulations.

Ligand-based Molecular Modeling of HDL Receptor SR-BI Inhibitors As Potent Anti-Hyperlipidemic Agents

Introduction:: The High-density lipoprotein (HDL) receptor, Scavenger receptor class B, type I (SRBI) plays a crucial role in lipoprotein metabolism, cholesterol homeostasis, and atherosclerosis. In the present study, a quantitative structure-activity relationship study (QSAR) investigation was conducted on a data set of 31 novel indolinyl thiazole-based inhibitors of SR-BI mediated lipid uptake. Method:: To build the QSAR model, Multiple linear regression analysis (MLR), partial least square analysis (PLS), and neural analysis (NN) were performed which were further evaluated internally as well as externally for the prediction of activity. The best QSAR model for MLR was selected with a correlation coefficient (r2) of 0.937, cross-validation r2cv of 0.908, and a standard error (S) value of 0.253. For PLS, r2 was 0.937 and for FFNN r2 was 0.961 (for the training set). This was further evaluated externally by a test set having r2 values 0.870 (MLR), 0.863(PLS), and 0.933(neural network) analysis. Result:: The final model comprised hydrophobic parameters (Lipole Z component) and steric parameters (molar refractivity and K alpha2 index). Conclusion:: All these descriptors generated comparable results which prove that the model generated is sound and has good predictability.

Pengetahuan dan Sikap Keuangan: Perspektif Manajemen Keuangan dan Financial Self-Eficacy di Lingkungan Desa

This research was conducted to determine the factors that influence the Financial Management Behavior of Women Empowering Family Welfare in Sukomulyo Village. This research aims to analyze the influence of Financial Knowledge and Financial Attitude variables on Financial Management Behavior with Financial Self-efficacy as a mediating variable among Mothers who are Family Welfare Empowerment (PKK) Administrators in Sukomulyo Village, Manyar District, Gresik Regency. The type of research used is quantitative with data analysis techniques using PLS (Partial Least Square) analysis with the SmartPLS program. The population and sample used in this research were the Family Welfare Empowerment (PKK) administrators at the Sukomulyo Village Community Association, totaling 135 respondents. The research results show that Financial Knowledge and Financial Attitudes have a positive effect on Financial Management Behavior. Apart from that, both also have a positive effect on Financial Self-efficacy, which in turn also influences Financial Management Behavior. Financial Self-efficacy also functions as a mediating variable, which connects Financial Knowledge and Financial Attitudes with Financial Management Behavior. These findings emphasize the importance of having good Financial Knowledge, a positive Financial Attitude, and strong Financial Self-efficacy in forming wise financial management behavior among mothers in the village.

Determinant Factors of Entrepreneurial Intention within Generation Z Students: Case of Koléa University Campus in Algeria

Purpose: This research work attempts to identify the determining factors of Koléa university campus generation Z students’ entrepreneurial intention.
 Design/Method/Approach: The applied research method is a quantitative approach in which a sample of 93 responses were analyzed using two software tools, IBM SPSS 25 and smartPLS4, and by adopting Structural Equation Modeling and Partial Least Squares for analysis and estimation.
 Findings: Results showed a significant and positive impact of subjective norms on the entrepreneurial intention of the study sample. However, entrepreneurial training, attitude towards entrepreneurship, and perceived behavioral control had no impact on the entrepreneurial intentions of these students.
 Theoretical Implications: This study contributes to the extent literature on generation Z students’ entrepreneurial intention in an Algerian context by highlighting the importance of subjective norms in fostering this intention.
 Practical Implications: Algerian universities should pay more attention to entrepreneurial education and trainings they offer to their students in order to incite them to create their own business.
 Originality/Value: Understanding the characteristics of generation Z students is important for universities and businesses. knowing what stimulates the generation Z entrepreneurial intention is both interesting and primordial. In addition, such study in the Algerian context is scarce and still not common.
 Research Limitations/Future Research: Limitations in this study include those related to the size of the sample and its area by focusing only on Koléa university students. Therefore, it is desirable to conduct more studies on the variables impacting entrepreneurial intention among Generation Z students enrolled in different Algerian institutions and to draw conclusions by extrapolating the results.
 Paper Type: Empirical
 
 JEL Classification: C12, C15, C29, I21, L26

Kualitas Sumber Daya Manusia Memoderasi Determinan Senjangan Anggaran

The study aims to analyze budget participation and budget clarity on budgetary slack, are moderated by human resources quality at BLUD Puskesmas in Jombang Regency. The population of this study are 34 BLUD Puskesmas di Jombang Regency with the research subjects are administration coordinator, data planning and management coordinator, and financial coordinator from BLUD Puskesmas. The number of samples in this study is 25 BLUD Puskesmas that obtained by using slovin formula, resulting in a total of 75 employees as respondents. The sampling technique used is simple random sampling with lottery method. The type research is quantitive research with the Partial Least Square (PLS) The steps used in PLS analysis technique are outer model analysis, inner model analysis, and hypothesis test. The result show that budget participation has a positive effect on budgetary slack, budget clarity has a negative effect on budgetary slack, human resources quality is not able to moderate budget participation on budgetary slack, and human resources quality is able to moderate budget clarity on budgetary slack.

The Effect of Learning Orientation on Business Performance Through Mediation of Innovation Dimensions in UMKM in Mataram City Indonesia

This research is directed to build a model that can provide predictions of the influence of learning orientation (X1) on the dimensions of innovation (product innovation/Y1; process innovation/Y2; marketing innovation/Y3 and organizational innovation/Y4) as well as the influence of each dimension of innovation on business performance (Z1) of small businesses in Mataram City. Observation data in this study were 78 small business actors, with the criteria of having run their business for at least three years. The analysis tool uses PLS (partial least square) analysis. According to the PLS work procedure, there are two stages of model formation, because the initial model still has indicators with a correlation value of less than 0.70, namely indicators X1.1 and Z1.1. The second model has met the indicator validity and reliability requirements, so there is no indicator removal process. The final model produced meets the predictive relevance requirements (Q2>0). All dimensions of innovation are positively and significantly influenced by learning orientation, but only two dimensions of innovation (product innovation and process innovation) have a positive and significant effect on the business performance of small businesses in Mataram City. This gives an indication of learning orientation as an absolute by the company owner to be made a culture in the organization and should be focused on product aspects and the application of appropriate technology.

The The Influence of Competency and Compensation on Performance and Job Satisfaction as an Intervening Study in Construction Services Companies

The purpose of this study is to ascertain how job satisfaction among employees in construction services organizations influences performance in terms of competency and compensation. The participants in this research were workers of PT Adhi Karya (Persero) Tbk, one of Indonesia's state owned enterprises providing construction services. The population of this study was 950, with a sample size of 255 people. Relying on a 5% percentage allowance, the calculation sample originates from the Isaac-Michael table. The research employs a quantitative methodology in conjunction with an explanatory strategy. The questionnaire used for data collection was given to 255 workers of PT Adhi Karya (Persero) Tbk who held manager-level positions. The Smart PLS (Partial Least Square Analysis) application is used in conjunction with the Structural Equation Model (SEM) analysis approach. According to the findings, competence and compensation have a considerable yet beneficial impact on performance. Job satisfaction is positively yet significantly impacted by both competence and compensation. Although there is a slight but favorable influence of job satisfaction on performance. Additionally, there is a positive but non-significant influence of competence and compensation on performance as measured by the intervening variable of job satisfaction. Keywords: Job satisfaction, employee performance, competency, and compensation

Pengaruh Kompensasi, Motivasi, dan Kompetensi SDM Terhadap Kinerja Karyawan: Studi Kasus pada UMKM Griya Tas Indah Sidoarjo

This study aims to explain the effect of compensation, motivation, and HR competence on employee performance. The object used in this research is the employees of UMKM Griya Tas Indah Sidoarjo. While the sample in this study were employees of UMKM Griya Tas Indah Sidoarjo. The sampling method used was saturated sampling technique with a total of 35 respondents. Data analysis in this study was carried out using the Partial Least Square (PLS) method which shows that all of these tests used a quantitative research design, data analysis in the form of descriptive statistics and PLS analysis. Based on the research results, it can be seen that: 1) the fulfillment variable is able to support employee performance improvement, 2) motivational variable is able to support employee performance improvement, 3) HR competence variable is able to support employee performance improvement.

Study on the Fingerprints of Acanthopanax trifoliatus Fractions with Varying Polarities and the Relationship Between Anti-inflammatory and Antioxidant Activity Using Multivariate Analysis

Objectives: To evaluate the Spectrum-Effect relationships between the High-Performance Liquid Chromatography (HPLC) Fingerprints of fractions with different polarities and the anti-inflammatory and antioxidant effects of A. trifoliatus and to identify its pharmacodynamic material basis. Materials and Methods: Chemical Fingerprints of A. trifoliatus fractions with different polarities (all fractions and ethyl acetate, n-butanol and water fractions) were obtained by HPLC, and Principal Component Analysis (PCA) was performed. The foot swelling and prostaglandin E2 (PGE2) content in mice induced by carrageenan were used as anti-inflammatory markers, and 2,2-diphenyl-1-picrylhydrazyl (DPPH) and 2,2’-azino-bis (3-ethylbenzothiazoline-6-sulfonic acid) (ABTS) methods were used as antioxidant indicators. Moreover, the Spectrum-Effect relationship between common peaks and efficacy value was conducted by Grey Relational Analysis (GRA) and Partial Least Squares analysis (PLS). Results: PCA identified three principal components, and all fractions of A. trifoliatus had good anti-inflammatory and antioxidant effects. Based on GRA and PLS analysis, peaks 1 and 2 (neochlorogenic acid), 4 and 5 (chlorogenic acid), 8, 9, 10, 11 (isochlorogenic acid B), and 12 were involved in anti-inflammatory efficacy, and peaks 1 and 2 (neochlorogenic acid), 3, 4, and 5 (chlorogenic acid), and 6, 7, 9, 10, and 13 (isochlorogenic acid A) were involved in antioxidant efficacy. Conclusion: This study on the Spectrum-Effect relationship of different polar fractions of A. trifoliatus provides data to support the discovery of the pharmacodynamic material basis of the anti-inflammatory and antioxidant properties of A. trifoliatus.

Ultratrace eNose Sensing of VOCs toward Breath Analysis Applications Utilizing an eNose-Based Analyzer.

This proof-of-principle study presents the ability of the recently developed iLovEnose to measure ultratrace levels of volatile organic compounds (VOCs) in simulated human breath based on the combination of multiple gas sensors. The iLovEnose was developed by our research team as a test bed for gas sensors that can be hosted in three serially connected compact low-volume and temperature-controlled compartments. Herein, the eNose system was equipped with conventional semiconducting metal oxide (MOX) gas sensors using a variety of base technologies providing 11 different sensor signals that were evaluated to determine six VOCs of interest at eight low to ultralow concentration levels (i.e., ranging from 3 to 0.075 ppm) at humid conditions (90% rh at 22 °C). The measurements were randomized and performed four times over a period of 2 weeks. Partial least-squares regression analysis was applied to estimate the concentration of these six analytes. It was shown that the iLovEnose system is able to discriminate between these VOCs and provide reliable quantitative information relevant for future applications in exhaled breath analysis as a diagnostic disease detection or monitoring device.

Sustainability of the cassava processed agro industry business after covid-19 pandemic

Cassava is a food plant that has many advantages and can be processed into various kinds of processed foods. Salatiga City is one of the areas that has the potential to develop the sustainability of cassava processing businesses. At the start of the Covid-19 pandemic, sales of processed cassava experienced a decline. Business sustainability starts from the increase in income and sales volume after Covid-19. This research aims to find out (1) a portrait of the success of cassava processing businesses after the Covid-19 pandemic; (2) analyse the stage of managerial ability and entrepreneurial behaviour of processed cassava agro-industry entrepreneurs;(3) the impact of managerial ability and entrepreneurial behaviour on the achievement of cassava processing businesses in Salatiga City. Purposive sampling is the sample strategy employed in this study. This research uses analysis of partial least squares (PLS) with the help of the app SmartPLS4.0. The results show (1) Currently, the average cassava agro-industry business has experienced an increase in income and sales volume of 41% since the Covid-19 pandemic period; (2) Forming managerial skills are implementation, organization, and supervision. Entrepreneurial behaviour is risk-taking, and creative and innovative; (3) Managerial ability and entrepreneurial behaviour have a significant influence on business success.

Aroma and taste analysis of pickled tea from spontaneous and yeast-enhanced fermentation by mass spectrometry and sensory evaluation

Anaerobically fermented pickled tea (PT) can be produced by spontaneous fermentation (SF) or yeast-enhanced fermentation (YF). Aroma and taste characteristics of PT during YF and SF were investigated using sensory evaluation, odour activity, aroma character impact values, HS-SPME-GC–MS, UPLC-QQQ-MS/MS, and spectrophotometry, annotating 198 volatile and 115 non-volatile components. The main contributing volatile components were β-ionone, and 1-octanol, promoted by YF and SF, and yielding floral and fruity aromas respectively. Additionally, compared with SF, YF promoted the formation of citronellol yielding a floral aroma, inhibited the stale aroma of methoxybenzenes, and reduced bitter, astringent, and sour tastes. Furthermore, partial least-squares regression analysis identified the main components related to the ‘acides aroma’ of PT as linalool oxide, n-decanoic acid, hexanoic acid, 3,7-dimethyl-2,6-octadienoic acid, 3-methyl-1-dodecyn-3-ol, and nerolidol. This application could be used as methodology for the comprehensive analysis of tea aroma and taste and these results can act as guidelines for PT production and quality control.