Equal Sample Sizes Research Articles

Interrelationships among lean HRM practices and their impact on firm performance: a comparison between the Jordanian and German models

PurposeLean management is a contemporary management system that firms adopt to boost their performance. Lean management can be integrated with human resources management to develop a new concept of lean human resources management (LHRM). This entails the implementation of several practices. However, the LHRM–performance paradigm remains underexplored in the literature. Hence, this study aims to examine the interrelationships between LHRM practices and the impacts of those practices on firm performance (FP).Design/methodology/approachUsing two equal-sized samples (n = 250 each) of manufacturing firms in Jordan and Germany, this study proposes two structural equation models (i.e. a Jordanian and a German models) depicting the interrelationships between LHRM practices and the impacts of those practices on FP. After testing these models, a comparison between them is conducted, producing findings with theoretical and practical implications.FindingsThe main findings of this study indicate that the average implementation of LHRM practices among German manufacturing firms is at a higher level than the average implementation among Jordanian firms. The findings also support the proposed interrelationships between LHRM practices and the impact of those practices on FP for both the Jordanian and German models.Originality/valueTo the best of the authors’ knowledge, this study is among the first to highlight the proposed relationships, both in general and in the context of comparing developed and developing countries. Its findings have important implications that can enable manufacturing managers to benefit from the implementation of LHRM practices to enhance FP in different contexts. These findings provide valuable insights for human resource managers and decision-makers and open several avenues for future research.

A Community Trial in Coastal Karnataka using Life Style Modifications to Assess its Impact on Hypertension and Diabetes.

In the management of hypertension and diabetes mellitus, a systematic response like modifications in lifestyles is needed along with the medication. The study was conducted to determine the impact of comprehensive lifestyle modifications on hypertension and diabetes and to compare it with that of physical activity alone as a health education intervention. A risk factor-based community intervention trial was conducted for one year in 3 villages in coastal Karnataka. The sample of 305 was calculated depending on the expected change in blood pressure and an equal sample size was drawn from each of the villages using a systematic random sampling method. Baseline data on blood pressure level, random blood sugar, and HbA1c levels were recorded. After 1 year of intervention, all the parameters were further recorded along with the adherence to medication for these non-communicable diseases. The mean difference between the groups suggested that participants with physical activity intervention reported a statistically significant reduction in systolic blood pressure. In the comprehensive lifestyle modification group, there was a significant reduction in both diastolic blood pressure and glycated hemoglobin levels (21 mmHg and 2.1%; p < 0.001). The study indicates that in the management of hypertension and diabetes mellitus, the impact of comprehensive lifestyle modifications was more significant compared to physical activity alone.

An improved statistical approach to compare means

&lt;abstract&gt;&lt;p&gt;In many experiments, our interest lies in testing the significance of means from the grand mean of the study variable. Sometimes, an additional linearly related uncontrollable factor is also observed along with the main study variable, known as a covariate. For example, in Electrical Discharge Machining (EDM) problem, the effect of pulse current on the surface roughness (study variable) is affected by the machining time (covariate). Hence, covariate plays a vital role in testing means, and if ignored, it may lead to false decisions. Therefore, we have proposed a covariate-based approach to analyze the means in this study. This new approach capitalizes on the covariate effect to refine the traditional structure and rectify misleading decisions, especially when covariates are present. Moreover, we have investigated the impact of assumptions on the new approach, including normality, linearity, and homogeneity, by considering equal or unequal sample sizes. This study uses percentage type Ⅰ error and power as our performance indicators. The findings reveal that our proposal outperforms the traditional one and is more useful in reaching correct decisions. Finally, for practical considerations, we have covered two real applications based on experimental data related to the engineering and health sectors and illustrated the implementation of the study proposal.&lt;/p&gt;&lt;/abstract&gt;

Comparison of profile-likelihood-based confidence intervals with other rank-based methods for the two-sample problem in ordered categorical data

ABSTRACT For ordered categorical data from randomized clinical trials, the relative effect, the probability that observations in one group tend to be larger, has been considered appropriate for a measure of an effect size. Although the Wilcoxon–Mann–Whitney test is widely used to compare two groups, the null hypothesis is not just the relative effect of 50%, but the identical distribution between groups. The null hypothesis of the Brunner–Munzel test, another rank-based method used for arbitrary types of data, is just the relative effect of 50%. In this study, we compared actual type I error rates (or 1 – coverage probability) of the profile-likelihood-based confidence intervals for the relative effect and other rank-based methods in simulation studies at the relative effect of 50%. The profile-likelihood method, as with the Brunner– Munzel test, does not require any assumptions on distributions. Actual type I error rates of the profile-likelihood method and the Brunner–Munzel test were close to the nominal level in large or medium samples, even under unequal distributions. Those of the Wilcoxon–Mann–Whitney test largely differed from the nominal level under unequal distributions, especially under unequal sample sizes. In small samples, the actual type I error rates of Brunner–Munzel test were slightly larger than the nominal level and those of the profile-likelihood method were even larger. We provide a paradoxical numerical example: only the Wilcoxon–Mann–Whitney test was significant under equal sample sizes, but by changing only the allocation ratio, it was not significant but the profile-likelihood method and the Brunner–Munzel test were significant. This phenomenon might reflect the nature of the Wilcoxon–Mann–Whitney test in the simulation study, that is, the actual type I error rates become over and under the nominal level depending on the allocation ratio.

Is it possible that the structure of tropical rainforests has recovered 40 years after clear-cutting?

Abstract The tropical rainforest of Bajo Calima, Buenaventura, Colombia, was known for its large biodiversity and enormous regeneration potential. During the 1970–90s, industrial use through clear-cutting gave rise to secondary forest (SF), which is now a collective property of the communities that inhabit it. The productivity of secondary forest would recover after 30 years according to the linear recovery trend, as predicted by Mazuera (1985). The purpose of conducting this research in Bajo Calima, Colombia was to quantify the productivity of SF at different ages after clear-cutting. Plots of 0.1 ha were selected after 23, 27, 31 and 35 years of SF following clear-cutting of the initial primary forest (PF). It is now managed through selective logging. Samples of equal size of PF and SF without selective logging, called mature secondary forest MSF (&gt; 40 years), were used as controls. The productivity variables of the SF expressed as basal area, volume (Vol) and aerial biomass (AB), on average for the four ages studied was 45%, 29% and 22% compared to the productivity of the PF, and 94%, 50% and 49% with respect to the productivity of the MSF. Without the opportunity to reach maturity the trend predicted by the recovery model was not achieved and the SF showed productive characteristics far below those of the initial primary forest.

Identification of pre-synaptic density networks using [11C]UCB-J PET imaging and ICA in mice

BackgroundSynaptic vesicle glycoprotein 2A (SV2A) is a vesicle glycoprotein involved in neurotransmitter release. SV2A is located on the pre-synaptic terminals of neurons and visualized using the radioligand [11C]UCB-J and positron emission tomography (PET) imaging. Thus, SV2A PET imaging can provide a proxy for pre-synaptic density in health and disease. This study aims to apply independent component analysis (ICA) to SV2A PET data acquired in mice to identify pre-synaptic density networks (pSDNs), explore how ageing affects these pSDNs, and determine the impact of a neurological disorder on these networks. MethodsWe used [11C]UCB-J PET imaging data (n = 135) available at different ages (3, 7, 10, and 16 months) in wild-type (WT) C57BL/6J mice and in diseased mice (mouse model of Huntington's disease, HD) with reported synaptic deficits. First, ICA was performed on a healthy dataset after it was split into two equal-sized samples (n = 36 each) and the analysis was repeated 50 times in different partitions. We tested different model orders (8, 12, and 16) and identified the pSDNs. Next, we investigated the effect of age on the loading weights of the identified pSDNs. Additionally, the identified pSDNs were compared to those of diseased mice to assess the impact of disease on each pSDNs. ResultsModel order 12 resulted in the preferred choice to provide six reliable and reproducible independent components (ICs) as supported by the cluster-quality index (IQ) and regression coefficients (β) values. Temporal analysis showed age-related statistically significant changes on the loading weights in four ICs. ICA in an HD model revealed a statistically significant disease-related effect on the loading weights in several pSDNs in line with the progression of the disease. ConclusionThis study validated the use of ICA on SV2A PET data acquired with [11C]UCB-J for the identification of cerebral pre-synaptic density networks in mice in a rigorous and reproducible manner. Furthermore, we showed that different pSDNs change with age and are affected in a disease condition. These findings highlight the potential value of ICA in understanding pre-synaptic density networks in the mouse brain.

The Association of Erythropoietin and Age-Related Macular Degeneration in Hemodialysis Patients: A Nationwide Population-Based Cohort Study.

This population-based retrospective cohort study investigated the effectiveness of erythropoietin (EPO) treatment in reducing the risk of age-related macular degeneration (AMD) in hemodialysis patients, using the National Health Insurance Research Data of Taiwan. From the database, we identified 147,318 end-stage renal disease (ESRD) patients on hemodialysis who had been diagnosed in 2000–2014 to establish the propensity-score-matched EPO user cohort and non-EPO user cohort with equal sample size of 15,992. By the end of 2016, the cumulative incidence of AMD in EPO users was about 3.29% lower than that in non-EPO users (Kaplan–Meier survival p < 0.0001). The risk of AMD was 43% lower in EPO users than in non-EPO users, with an adjusted hazard ratio (aHR) of 0.57 (95% confidence interval (CI) = 0.51–0.64) estimated in the multivariate Cox model. A significant negative dose–response relationship was identified between the EPO dosage and the risk of AMD (p < 0.0001). Another beneficial effect of EPO treatment was a reduced risk of both exudative AMD (aHR = 0.48, 95% CI = 0.40–0.61) and non-exudative AMD (aHR = 0.61, 95% CI = 0.53–0.69), also in similar dose–response relationships (p < 0.0001). Our findings suggest that EPO treatment for hemodialysis patients could reduce AMD risk in a dose–response relationship.

Multivariate Kruskal_Wallis tests based on principal component score and latent source of independent component analysis

SummaryAnalysing multivariate and high_dimensional multi_sample data is essential in many scientific fields. One of the most crucial and popular topics in modern nonparametric statistics is multi_sample comparison problems for such multivariate and high_dimensional data. The Kruskal_Wallis test is widely used in the multi_sample problem. For multivariate or high_dimensional data, it is imperative to specify how to determine the ranks of individual vector_valued observations in terms of various distance metrics. Alternatively, one can combine the concept of principal component scores or independent component scores with the Kruskal_Wallis test. A simple but powerful Kruskal_Wallis test based on the principal component scores is discussed in this paper for the multivariate and high_dimensional data. Another type of Kruskal_Wallis test based on latent sources of independent component analysis is constructed as a competitor. These tests are suitable for testing the difference in the location vector, scale matrix or both and can be used with equal and unequal sample sizes. These tests_ power performances are thoroughly compared with traditional distance_based Kruskal_Wallis tests for multivariate data using simulation based on Monte Carlo for various population distributions. We include an illustration of the proposed tests using real data. The paper concludes with some remarks and directions for future research.

Standard deviation estimation from sums of unequal size samples

Abstract In numerous industrial and related activities, the sums of the values of, frequently, unequal size samples are systematically recorded, for several purposes such as legal or quality control reasons. For the typical case where the individual values are not or no longer known, we address the point estimation, with confidence intervals, of the standard deviation (and mean) of the individual items, from those sums alone. The estimation may be useful also to corroborate estimates from previous statistical process control. An everyday case of a sum is the total weight of a set of items, such as a load of bags on a truck, which is used illustratively. For the parameters mean and standard deviation of the distribution, assumed Gaussian, we derive point estimates, which lead to weighted statistics, and we derive confidence intervals. For the latter, starting with a tentative reduction to equal size samples, we arrive at a solid conjecture for the mean, and a proposal for the standard deviation. All results are verifiable by direct computation or by simulation in a general and effective way. These computations can be run on public web pages of ours, namely for possible industrial use.

Impact of Maternal Education and Age on Weight of Child at Birth: Use of Multinomial Logistic Model

The World Health Organization (WHO) prescribed 2.5 kilograms to 4.2 kilograms as the standard for normal birth weight (NBW) and every child whose birth weight is below the lowest bound is regarded as low birth weight (LBW) while above the highest bound is regarded as macrosomia. The odds for a LBW child to die as reported is about 40 times high when compared to a NBW child and these overwhelming death records are higher in developing countries. Therefore, urgent research about the causes of LBW especially in developing countries is very necessary and this motivated this research in Nigeria. In this paper, the Multinomial Logistic Regression (MLR) model was applied to secondary data from the 2018 Nigerian Demographic and Health Survey (NDHS) report to predict the probability of giving birth to NBW and macrosomia babies referenced to LBW babies. The maternal education level and age were considered as the predictor variables. The data was naturally stratified by maternal education level, that is (1 = Higher Education, 2 = Secondary Education, 3 = Primary Education, and 4 = No Education). The equal sample allocation technique which assigns equal stratum sample sizes (ni = 200 for the ith maternal education level) was adopted. The 800 sample size was reduced to 735 after screening for outliers in the maternal age variable. Considering the 54 LBW babies, 57% (0.5741) were from mothers with no education. The results showed that maternal education level and age have causal effects on child birth weight in Nigeria. Younger mothers (less than 28years) are 96.5% likely to have LBW babies while mothers who attained a minimum of primary, secondary, and higher education are 88.00%, 82.00%, and 57.90% likely to have NBW babies respectively when compared to those with no formal education. The research recommends that mothers should acquire at least primary school education and early child marriage (less than 28years) of the girl child should be discouraged.

Linking leptin in GCF with tooth movement among Indians.

It is of interest to evaluate the association of orthodontic tooth movement with concentration of leptin in Gingival Crevicular Fluid (GCF).Thirty orthodontic patients of both genders with equal sample size were included for the present study. Concentration of leptin was assessed at baseline (T0), 1 hr after application of force (T1), 24 hours later (T2), 7 days after application of force (T3), and 1 month after application of orthodontic force (T4). Using strips of filter paper, GCF was collected from the gingival sulcus on distal aspect of the right maxillary canine. Distalized tooth movement was evaluated by measuring the difference on dental casts, at baseline and one month after force application. One-way ANOVA with Bonferroni correction and Pearson's correlation test were used to analyze the data. Average concentration of leptin in GCF raises from baseline (T0) to 1 hours after application of force (T1), then increased to peak after 24 hours (T2), and declined to a minimum value after 7 days (T3) and again raises after 1 month (T4), closer to the base line value (T0), and this was statistically significant (P < 0.05). There was significant association of the overall average concentration of leptin to degree of tooth movement (correlation coefficient = 0.625). There was a biphasic change in GCF leptin concentration during one cycle of orthodontic force application, thus, a significant association between rates of tooth movement with GCF leptin concentration is noted.

Effects of Complex Rehabilitation Program on Reducing Pain and Disability in Patients with Lumbar Disc Protrusion—Is Early Intervention the Best Recommendation?

(1) Background: Due to its frequency and possible complications, low back pain (LBP) has a high social impact, it is a common problem of the active population and the second reason for visiting a physician. In patients with lumbar disc protrusion (LDP), one of the most common causes of LBP, the nucleus pulposus bulges against the disc and then protrudes into the spinal cord, but the annulus fibrosus remains intact; (2) Objectives: The primary objective of this study was to determine the efficacy of a rehabilitation treatment (RT) comprising electrotherapy (ET), hydrotherapy (HT) and individualized physical therapy (PT) versus ET alone in patients with LDP. The second objective was to investigate whether there is a correlation between early RT and the symptomatology of patients with LDP; (3) Methods: The research was conducted between July 2021 and January 2022 at the Ceres Hotel Treatment Centre from Baile 1 Mai, Romania, and all the study subjects signed an informed consent form. For this study, the block randomization method was used to randomize subjects into groups that resulted in equal sample size, in order to maintain a reasonably good balance among groups. Therefore, the two groups had the same number of subjects (30 subjects) and the randomization was made taking into account the patient’s motivation or the subject’s willingness to receive not only electrotherapy treatment, but also the physical exercises and hydrotherapy. The eligibility criteria were: low back pain for more than three months, an MRI confirmed diagnosis of LDP (without dural compression), and ability to perform a PT program. The control group received only a classical ET program. In addition, the patients in the experimental group received a complex individualized PT program associated with HT and ET. To achieve these objectives, the study subjects were monitored for spinal mobility (lateral lumbar flexion—LLF, index fingers-ground—IFG, lumbar Schober tests for flexion—LS, Inverted Schober test for extension—ILS), trunk flexor and extensor muscle strength (LF strength, LE strength), level of pain (Short Form McGill Pain Questionnaire—SF-MPQ, Visual Analogue Scale—VAS), and the degree of limitation in activities of daily living (Oswestry Disability Index—ODI); (4) Results: Comparing the evolution of the subjects, using the One-Way ANOVA between groups, we observed a significant improvement in all variables [SF-MPQ (95% CI, 7.996/11.671), VAS (95% CI, 1.965/3.169), mobility FTF (95% CI, −7.687/−3.940), LS (95% CI, 2.272/2.963), LE strength (95% CI, −5.676/−3.324), LF strength (95% CI, −5.970/−3.630), disability (95% CI, 8.026/10.441) after six months of treatment for the experimental group subjects. A clear correlation was found, using the Bravis–Pearson test, between the earliest possible initiation of RT and improvement of patients’ symptoms; (5) Conclusion: The current study proves the importance of combining ET with HT and PT. The earlier the RT is implemented, the lower the pain perception and level of disability associated with the lumbar disease.

Monotonicity conditions for avoiding counterintuitive decisions in basket trials.

In a basket trial, a new treatment is tested in different subgroups, called the baskets. In oncology, the baskets usually comprise patients with different primary tumor sites but a common biomarker. Most basket trials are uncontrolled phase II trials and investigate a binary endpoint such as tumor response. To combine the data of baskets that show a similar response to the treatment, many basket trial designs use Bayesian borrowing methods. This increases the power compared to a basketwise analysis. However, it can lead to posterior probabilities that are not monotonically increasing in the number of responses. We show that, as a consequence, two types of counterintuitive decisions can arise-one that occurs within a single trial and one that occurs when the results are compared between different trials. We propose two monotonicity conditions for the inference in basket trials. Using a design recently proposed by Fujikawa and colleagues, we investigate the case of a single-stage basket trial with equal sample sizes in all baskets and show that, as the number of baskets increases, these conditions are violated for a wide range of different borrowing strengths. We show that in the investigated scenarios pruning baskets can help to ensure that the monotonicity conditions hold and investigate how this affects type I error rate andpower.

Nurses’ authentic leadership and their perceptions of safety climate: differences across areas of work and hospitals

PurposeThis study aims to compare nurses’ authentic leadership and perceptions of the safety climate and concepts association according to different areas of work and types of hospitals.Design/methodology/approachA cross-sectional design was used to conduct this comparative study on 314 Jordanian nurses. The Authentic Leadership Questionnaire (ALQ) and the Safety Climate Survey (SCS) were used.FindingsNurses in private hospitals were more educated. True leadership was mild. Unit nurses had higher ALQ and subscale mean scores. Armed forces hospitals had the highest ALQ subscales, while governmental hospitals had the lowest. The ALQ mean scores favored military hospitals. Governmental hospitals have a negative safety climate. Unit nurses had a higher SCS mean than ward nurses. Military, governmental and private hospitals are rated the safest. Nurses benefited from higher SCS scores in military hospitals. Nurses’ ALQ and safety climate perceptions were moderately positive.Research limitations/implicationsA larger, randomized and equal-sized sample is recommended in future studies to conclude different areas of work and hospitals. It is also recommended to report the confidence interval in further studies using different statistical methods, increasing confidence when interpreting statistical significance variables. Other mediating, moderating and predicting variables could be studied and compared across different areas of work and types of hospitals. Sample characteristics should be handled as confounding variables in the next planned study using various ways to control confounding variables such as randomization, restriction, matching, regression and statistical control. The authors plan to statistically control for the confounding variables by entering them into the regression model. Future studies could investigate safety culture; both safety culture and safety climate are formative and inclusive terms (Experts Insight, 2017).Practical implicationsThis paper fills in the gap in the literature and practice. Authentic leadership is associated with safety climate perceptions and varies across different areas of work and hospitals. Interventions are required to improve safety climate perceptions and promote authentic leadership in all settings and hospitals. Military hospitals ranked the highest in nurses’ perceptions of authentic leadership and safety climate.Social implicationsThe current study’s favorable association between authentic leadership and safety climate measurement would apply to many high-risk institutions, including public and private hospitals. It becomes necessary to include the impacts of authentic leadership on the safe climate within the nursing curriculum and continuing education courses. This may be put into action by executing a hands-on activity, followed by information and reflection conversations that highlight the link between authentic leadership and safety climate measurement. According to the findings of this study, authentic leadership appears to be a basic block in making a difference in nurses’ views of safety climate.Originality/valueAuthentic leadership style is a relatively new concept in the health-care sector, and its link to safety climate security still needs empirical evidence. It is still unclear how leadership resulted in more effective outcomes (Maziero et al., 2020). Few studies investigated both the concepts of authentic leadership and the nursing safety climate (Dirik and Intepeler, 2017; Lee et al., 2019a; Woo and Han, 2018). Aside from the scarcity of studies, no study has compared “working area,” “department” or “hospital type” concepts. Few comparative studies have been conducted using concepts of interest. For example, authentic leadership was linked to empowerment and burnout (Laschinger et al., 2013) and nurses’ satisfaction with safety climates (Vatani et al., 2021). No research has examined authentic leadership in Jordan’s nursing and health-care context. Few studies focused on the safety climate other than authentic leadership (Abualrub et al., 2012) or the safety culture in Jordan rather than the safety climate (Khater et al., 2015).

Proposed tests for location and scale in a nondecreasing ordered alternative

Six nonparametric tests are proposed for the nondecreasing ordered alternative when testing for a difference in either location or scale. The six tests are various combinations of a well-known ordered alternative test for location and a technique that Moses used to convert a scale testing problem into a location testing problem by transforming the data. A simulation study is conducted to determine how well the proposed tests maintain their significance levels. Powers are estimated for the proposed tests under a variety of conditions for three, four and five populations. Several types of variable parameters are considered: when the location parameters are different and the scale parameters are equal; when the location parameters are equal and the scale parameters are different; when the location and scale parameters are both different. Equal and unequal sample sizes of 18 and 30 are considered. Subgroup sizes of 3 and 6 are both used when applying the Moses technique. Recommendations are given.

Harmonized Phenotypes for Anxiety, Depression, and Attention-Deficit Hyperactivity Disorder (ADHD)

In multi-cohort consortia, the problem often arises that a phenotype is measured using different questionnaires. This study aimed to harmonize scores based on the Child Behaviour Check List (CBCL) and the Strength and Difficulties Questionnaire (SDQ) for anxiety/depression and ADHD. To link the scales, we used parent reports on 1330 children aged 10–11.5 years from the Raine study on both SDQ and CBCL. Harmonization was done based on Item Response Theory. We started from existing CBCL and SDQ scales related to anxiety/depression and ADHD (theoretical approach). Next, we conducted a data-driven approach using factor analysis to validate the theoretical approach. Both approaches yielded similar scales, validating the combination of existing scales. In addition, we studied the impact of harmonized (IRT-based) scores on the statistical power of the results in meta-analytic gene-finding studies. The results showed that the IRT-based harmonized scores increased the statistical power of the results compared to sum scores, even with an equal sample size. These findings can help future researchers to harmonize data from different samples and/or different questionnaires that measure anxiety, depression, and ADHD, in order to obtain the larger sample sizes, to compare research results across subpopulations or to increase generalizability, the validity or statistical power of research results. We recommend using our item parameters to estimate harmonized scores that represent commensurate phenotypes across cohorts, and we explained in detail how other researchers can use our results to harmonize data in their studies.

Thumbs up! A Pilot Study of a Positive Psychology Intervention for Children in Greece

The current study aimed to test the hypothesis that a newly developed multi-component 8-week Positive Psychology Intervention (PPI) programme for children could lead to a significant decrease in negative emotion, state anxiety, trait anxiety, and a significant increase in hope and positive emotions. Participants were recruited online and assigned randomly to the experimental and control groups with equal sample sizes (N = 8) groups for this study. Each participant completed a battery of self-reported questionnaires before and after the completion of the programme. Measurements included Hope, STAI, PANAS and demographic self-reported questionnaires. Hope and positive emotions increased, whereas negative emotions, trait anxiety and state anxiety decreased. The results supported our hypothesis that PPIs could be considered a successful alternative intervention or prevention for children.

Two-sample test for equal distributions in separate metric space: New maximum mean discrepancy based approaches

This article develops statistical methods for testing the equality of two distributions based on two independent samples generated in some separable metric space. Such methods are broadly applicable in identifying similarity or distinction of two complicated data sets (e.g., high-dimensional data or functional data) collected in a wide range of research or industry areas, including biology, bioinformatics, medicine, material science, among others. Recently a so-called maximum mean discrepancy (MMD) based approach for the above two-sample problem has been proposed, resulting in several interesting tests. However, the main theoretical and numerical results of these MMD based tests depend on the very restricted assumption that the two samples have equal sample sizes. In addition, these tests are generally implemented via permutation when the equal sample size assumption is violated. In real data analysis, this equal sample size assumption is hardly satisfied, and dropping away some of the observations often means the loss of priceless information. It is also of interest to know if an MMD-based test can be conducted generally without using permutation. In this paper, we further study this MMD based approach with the equal sample size assumption removed. We establish the asymptotic null and alternative distributions of the MMD test statistic and its root-n consistency. We propose methods for approximating the null distribution, resulting in easy and quick implementation. Numerical experiments based on artificial data and two real data sets from two different areas of applications demonstrate that in terms of control of the type I error level and power, the resulting tests perform better or no worse than several existing competitors.

Genetic Characterization of Pathogenic Escherichia Coli Isolated from Smallholding Dairy Buffaloes, their Products, and Some Environmental Sources

This study was conducted to evaluate the potential existence of pathogenicEscherichia coli in smallholding dairy buffaloes, their products as well as in some environmental sources. In total, 150 samples including an equal sample size (n = 25) of raw milk, Kareish cheese, water, feed, udder and rectal swabs were examined. Phenotypic and genotypic procedures were used to characterize the bacterial population. Twenty-eight isolates were confirmed as E. coli from the examined samples (18.66%). The recovered isolates were categorized as Enterohemorrhagic E. coli (n=11),Enteropathogenic E. coli(n=9), Enterotoxigenic E. coli(n= 5)and Enteroinvasive E. coli (n=3). All isolates were resistant to erythromycin followed by oxacillin (89.28%), and nalidixic acid (67.85%), while 96% of the recovered strains displayed high sensitivity to imipenem. A great proportion of the recovered E. coli (67.9%) exhibited multidrug resistance. The majority of isolates (92.9%) harbored stx1either alone or in association with stx2 which present in 60.7% (17/28) while eaeA genes were detected in 50% among the recovered isolates in association with stx1 or combined with stx2 (n =11). Twelve isolates (42.86%) expressed all the examined beta lactamase encoding genes; while only 25% of the isolates harbored all tested beta lactamase genes in common with stx1, stx2 and eaeA genes.The results herein indicated that the pathogenicE. coli could be present in the examined samples which pose a relevant threat and negative impact on animal as well as consumer health. The study emphasizes the necessity of developing long-term strategies to assure dairy food safety.

In vitro antimicrobial effects of green tea, microwaving, cold boiled water, and chlorhexidine on Streptococcus mutans and Candida albicans on silicone pacifiers

This study aimed to compare the antimicrobial effects of green tea, microwaving, cold boiled water, and chlorhexidine (CHX) on Streptococcus mutans and Candida albicans on silicone pacifiers. In this in vitro experimental study, 60 equal-size samples of silicone pacifiers were cut, ultraviolet sterilized, and randomly divided into two groups (n = 30) for immersion in 0.5 McFarland standard suspension of S. mutans and C. albicans. The samples in each group were then randomly divided into five subgroups (n = 6) for disinfection with 0.12% CHX, cold boiled water, green tea, microwaving for 7 min, and distilled water. The sample suspensions were cultured on blood agar (for S. mutans) and Sabouraud dextrose agar (for C. albicans) and incubated. The number of colonies was counted after 24 and 48 h. Data were analyzed using the Kruskal-Wallis and Mann-Whitney tests (P < 0.05). At 24 and 48 h, the S. mutans colony count was the lowest in CHX and green tea subgroups followed by microwave, cold boiled water, and distilled water subgroups (P < 0.05). CHX and green tea can significantly decrease the S. mutans and C. albicans colony count on silicone pacifiers.