Traditional Laboratory Environment Research Articles

Hydration conditions as a critical factor in antibiotic-mediated bacterial competition outcomes.

Antibiotic secretion plays a pivotal role in bacterial interference competition; yet, the impact of environmental hydration conditions on such competition is not well understood. Here, we investigate how hydration conditions affect interference competition among bacteria, studying the interactions between the antibiotic-producing Bacillus velezensis FZB42 and two bacterial strains susceptible to its antibiotics: Xanthomonas euvesicatoria 85-10 and Pseudomonas syringae DC3000. Our results show that wet-dry cycles significantly modify the response of the susceptible bacteria to both the supernatant and cells of the antibiotic-producing bacteria, compared to constantly wet conditions. Notably, X. euvesicatoria shows increased protection against both the cells and supernatants of B. velezensis under wet-dry cycles, while P. syringae cells become more susceptible under wet-dry cycles. In addition, we observed a reciprocal interaction between P. syringae and B. velezensis, where P. syringae inhibits B. velezensis under wet conditions. Our findings highlight the important role of hydration conditions in shaping bacterial interference competition, providing valuable insights into the microbial ecology of water-unsaturated surfaces, with implications for applications such as biological control of plant pathogens and mitigating antibiotic resistance.IMPORTANCEOur study reveals that hydration conditions, particularly wet-dry cycles, significantly influence antibiotic-mediated competition between bacterial species. We revealed that the effectiveness of antibiotics produced by Bacillus velezensis against two susceptible bacterial species: Xanthomonas and Pseudomonas varies based on these hydration conditions. Unlike traditional laboratory environments, many real-world habitats, such as soil, plant surfaces, and even animal skin, undergo frequent wet-dry cycles. These conditions affect bacterial competition dynamics and outcomes, with wet-dry cycles providing increased protection for some bacteria while making others more susceptible. Our findings highlight the importance of considering environmental hydration when studying microbial interactions and developing biological control strategies. This research has important implications for improving agricultural practices and understanding natural microbial ecosystems.

Validation of the g.tec Unicorn Hybrid Black wireless EEG system.

Although dry and hybrid-style electrode technology has been well validated, systems utilizing these electrodes have not been widely adopted. One reason for this may be that the systems incorporating such technology present limitations that are fundamental to the EEG approach. The g.tec Unicorn Hybrid Black system, a low density Bluetooth EEG amplifier, however, attempts to address many of these limitations to allow greater flexibility to replicate methods used with traditional EEG amplifiers and extend them to more novel applications. The aim of the present investigation was to validate the g.tec Unicorn Hybrid Black amplifier to determine if it provides comparable data to a traditional laboratory-based system when no electrode preparation is utilized or if a saline-based solution is necessary to obtain sufficient signal quality. Stimulus-locked ERPs and EEG power spectrum data were concurrently recorded using both the Unicorn Hybrid Black amplifier and a traditional high-end laboratory-based low-impedance wired system. Findings suggest that the Unicorn Hybrid Black provides valid measures for investigations of frequency spectra even with no conductive solution applied. However, to obtain valid assessments of event-related brain potentials, it appears necessary to use a conductive solution for electrode preparation. This system appears well suited to allow for high-quality and flexible EEG measures available outside of traditional laboratory environments.

Joint Activity Design Evaluation Tools for Conducting Staged-World Studies

Intelligence analysis requires an analyst to search for meaningful events in vast amounts of distributed data and synthesize those events into insights to inform decision-making. Because of the complexity, dynamics of the ecology, and typical functions of work, analysis performance can be difficult to study in traditional laboratory environments. Staged-world studies, which maintain experimental control while preserving the complexity of the work domain, represent a promising approach to study analyst performance. To support an ongoing research program, we are developing the Joint Activity Design Evaluation (JADE) platform, a software tool for conducting staged-world studies within the intelligence analysis (IA) domain. Herein, we describe three of JADE’s core capabilities for presenting scenarios based on common challenges of cognitive work, eliciting participant responses, and storing and displaying pertinent data. As JADE continues to mature and add new features, we expect it to become a tool for researchers to conduct staged-world studies across a broader range of application domains.

Divergent neural and endocrine responses in wild-caught and laboratory-bred Rattus norvegicus

Although rodents have represented the most intensely studied animals in neurobiological investigations for more than a century, few studies have systematically compared neural and endocrine differences between wild rodents in their natural habitats and laboratory strains raised in traditional laboratory environments. In the current study, male and female Rattus norvegicus rats were trapped in an urban setting and compared to weight-and sex-matched conspecifics living in standard laboratory housing conditions. Brains were extracted for neural assessments and fecal boli were collected for endocrine [corticosterone and dehydroepiandrosterone (DHEA)] assays. Additionally, given their role in immune and stress functions, spleen and adrenal weights were recorded. A separate set of wild rats was trapped at a dairy farm and held in captivity for one month prior to assessments; in these animals, brains were processed but no hormone data were available. The results indicated that wild-trapped rats exhibited 31% heavier brains, including higher densities of cerebellar neurons and glial cells in the bed nucleus of the stria terminalis. The wild rats also had approximately 300% greater spleen and adrenal weights, and more than a six-fold increase in corticosterone levels than observed in laboratory rats. Further research on neurobiological variables in wild vs. lab animals will inform the extensive neurobiological knowledge base derived from laboratory investigations using selectively bred rodents in laboratory environments, knowledge that will enhance the translational value of preclinical laboratory rodent studies.

Feasibility of Markerless Motion Capture for Three-Dimensional Gait Assessment in Community Settings.

Three-dimensional (3D) kinematic analysis of gait holds potential as a digital biomarker to identify neuropathologies, monitor disease progression, and provide a high-resolution outcome measure to monitor neurorehabilitation efficacy by characterizing the mechanisms underlying gait impairments. There is a need for 3D motion capture technologies accessible to community, clinical, and rehabilitation settings. Image-based markerless motion capture (MLMC) using neural network-based deep learning algorithms shows promise as an accessible technology in these settings. In this study, we assessed the feasibility of implementing 3D MLMC technology outside the traditional laboratory environment to evaluate its potential as a tool for outcomes assessment in neurorehabilitation. A sample population of 166 individuals aged 9–87 years (mean 43.7, S.D. 20.4) of varied health history were evaluated at six different locations in the community over a 3-month period. Participants walked overground at self-selected (SS) and fastest comfortable (FC) speeds. Feasibility measures considered the expansion, implementation, and practicality of this MLMC system. A subset of the sample population (46 individuals) walked over a pressure-sensitive walkway (PSW) concurrently with MLMC to assess agreement of the spatiotemporal gait parameters measured between the two systems. Twelve spatiotemporal parameters were compared using mean differences, Bland-Altman analysis, and intraclass correlation coefficients for agreement (ICC2,1) and consistency (ICC3,1). All measures showed good to excellent agreement between MLMC and the PSW system with cadence, speed, step length, step time, stride length, and stride time showing strong similarity. Furthermore, this information can inform the development of rehabilitation strategies targeting gait dysfunction. These first experiments provide evidence for feasibility of using MLMC in community and clinical practice environments to acquire robust 3D kinematic data from a diverse population. This foundational work enables future investigation with MLMC especially its use as a digital biomarker of disease progression and rehabilitation outcome.

Reducing measurement error with ecologically valid testing methods

Abstract‘Six solutions for more reliable infant research’ outlines important steps in improving research with the youngest of participants. Here, we suggest that a complimentary avenue for further improving reliability can be found in employing more ecologically valid tasks. Because laboratory tasks are often designed as simple, heavily controlled representations of a construct, they can be devoid of the necessary context in which the construct naturally unfolds. We posit that additional error is generated in translating laboratory task metrics back to the construct of interest. Thus, it may be necessary to supplement more traditional laboratory tasks with iterations that more closely match the research construct of interest and how it may unfold in the ‘real world’. We make suggestions for adjusting to the ‘noise’ incurred by moving research out of traditional laboratory environments, while also recognizing how these adjustments may improve the sociodemographic profiles within research studies.

Profiling RT-LAMP tolerance of sequence variation for SARS-CoV-2 RNA detection.

The ongoing SARS-CoV-2 pandemic has necessitated a dramatic increase in our ability to conduct molecular diagnostic tests, as accurate detection of the virus is critical in preventing its spread. However, SARS-CoV-2 variants continue to emerge, with each new variant potentially affecting widely-used nucleic acid amplification diagnostic tests. RT-LAMP has been adopted as a quick, inexpensive diagnostic alternative to RT-qPCR, but as a newer method, has not been studied as thoroughly. Here we interrogate the effect of SARS-CoV-2 sequence mutations on RT-LAMP amplification, creating 523 single point mutation "variants" covering every position of the LAMP primers in 3 SARS-CoV-2 assays and analyzing their effects with over 4,500 RT-LAMP reactions. Remarkably, we observed only minimal effects on amplification speed and no effect on detection sensitivity at positions equivalent to those that significantly impact RT-qPCR assays. We also created primer sets targeting a specific short deletion and observed that LAMP is able to amplify even with a primer containing multiple consecutive mismatched bases, albeit with reduced speed and sensitivity. This highlights RT-LAMP as a robust technique for viral RNA detection that can tolerate most mutations in the primer regions. Additionally, where variant discrimination is desired, we describe the use of molecular beacons to sensitively distinguish and identify variant RNA sequences carrying short deletions. Together these data add to the growing body of knowledge on the utility of RT-LAMP and increase its potential to further our ability to conduct molecular diagnostic tests outside of the traditional clinical laboratory environment.

The effect of virtual laboratory applications prepared for Geometrical Optics Lesson on students’ achievement levels and attitudes towards Physics

The purpose of this study is to investigate the effect of teaching through a virtual laboratory prepared using simulations teaching materials and that are based on constructivist thought about geometrical optics upon the students’ academic success and their attitudes towards physics. Quasi-experimental pretest and posttest control groups was used as the research method. While the independent variable of the study is teaching method that is based on virtual laboratory application, the dependents variables are students’ success at physics lesson and their attitude towards physics. The study was carried out with 59 students from the same grade but a different section and taking Physics II lesson that is taught in Department of Computer and Instructional Technologies in the spring term of 2013 and 2014 academic year. One of the sections was objectively determined as the experimental group and the other one is determined as the control group. The subject was taught to 29 students in the experimental group in a virtual laboratory environment which was created using simulations, and 30 students in the control group was taught the same subject in a traditional laboratory environment. As a result in this study, it was seen that teaching in the virtual laboratory environment where simulations were used in the subject of Geometrical Optics was more affective in physics success than teaching in traditional laboratory environment but there was no meaningful difference in attitudes towards physics.

Conducting speech perception experiments remotely: Some tools, successes, and challenges

The use of remote (i.e., web-based) data collection for psycholinguistics research has proliferated in recent years, reflecting the emergence of new tools for promoting high-quality data collection beyond the traditional laboratory environment. This is particularly true this past year, demonstrating one way that the pandemic has transformed research in the short-term. In the long-term, remote approaches will remain a powerful tool in the domain of psycholinguistics, in part because they help (1) promote diversity among participant samples and (2) increase feasibility of the new best practices for promoting reproducibility of research (e.g., larger sample sizes, in-house replications, assessing generalization to novel stimulus sets). However, embracing remote data collection is not without its challenges, especially for speech perception researchers who require some degree of control over the listening environment and participants’ linguistic background. In this talk, I will describe tools, successes, and challenges related to our experiences in conducting remote speech perception experiments for a variety of phenomena (e.g., categorical perception, perceptual learning, talker adaptation, Ganong effect), tasks (e.g., phonetic identification, lexical decision, talker discrimination, transcription), and dependent measures (e.g., reaction time, accuracy, sensitivity, psychometric response functions).

#DryLabs20: A New Global Collaborative Network to Consider and Address the Challenges of Laboratory Teaching with the Challenges of COVID-19

Since the sudden emergence of COVID-19 global pandemic, all educational institutions have looked to move resources and delivery online. Some institutions had already embraced delivering instruction in this way; however, broader adaptation to this teaching style is new to many educators. While the teaching of theoretical concepts is more easily transferred to a blended learning environment, the teaching of practical chemistry poses significant challenges, yet it is crucial to the chemist’s identity. Here we describe the establishment of a new, international, network to consider how practical chemistry can be taught outside of the traditional laboratory environment and invite readers of this special edition of the journal to join. Meeting fortnightly and maintaining links through a shared networked drive between meetings, the network has been accessed by over 100 delegates in the U.K., mainland Europe, North America, and Australasia. The traditional siloes of chemistry have not defined the discussions, which have instead focused on logistical aspects such as social distancing and the pastoral role of the laboratory environment. Initial evaluation shows the network is valued by its members and is making progress toward its aims.

A Review to Weigh the Pros and Cons of Online, Remote, and Distance Science Laboratory Experiences

The effectiveness of traditional face to face labs versus non-traditional online, remote, or distance labs is difficult to assess due to the lack of continuity in the literature between terminology, standard evaluation metrics, and the use of a wide variety non-traditional laboratory experience for online courses. This narrative review presents a representative view of the existing literature in order to identify the strengths and weaknesses of non-traditional laboratories and to highlight the areas of opportunity for research.Non-traditional labs are increasingly utilized in higher education. The research indicates that these non-traditional approaches to a science laboratory experience are as effective at achieving the learning outcomes as traditional labs. While this is an important parameter, this review outlines further important considerations such as operating and maintenance cost, growth potential, and safety. This comparison identifies several weaknesses in the existing literature. While it is clear that traditional labs aid in the development of practical and procedural skills, there is a lack of research exploring if non-traditional laboratory experiments hinder student success in subsequent traditional labs. Additionally, remote lab kits blur the lines between modality by bringing experiences that are more tactile to students outside of the traditional laboratory environment. Though novel work on non-traditional labs continues to be published, investigations are still needed regarding cost differences, acquisition of procedural skills, preparation for advanced work, and instructor contact time between traditional and non-traditional laboratories.

SABRE hyperpolarization enables high-sensitivity 1H and 13C benchtop NMR spectroscopy.

Benchtop NMR spectrometers operating with low magnetic fields of 1-2 T at sub-ppm resolution show great promise as analytical platforms that can be used outside the traditional laboratory environment for industrial process monitoring. One current limitation that reduces the uptake of benchtop NMR is associated with the detection fields' reduced sensitivity. Here we demonstrate how para-hydrogen (p-H2) based signal amplification by reversible exchange (SABRE), a simple to achieve hyperpolarization technique, enhances agent detectability within the environment of a benchtop (1 T) NMR spectrometer so that informative 1H and 13C NMR spectra can be readily recorded for low-concentration analytes. SABRE-derived 1H NMR signal enhancements of up to 17 000-fold, corresponding to 1H polarization levels of P = 5.9%, were achieved for 26 mM pyridine in d4-methanol in a matter of seconds. Comparable enhancement levels can be achieved in both deuterated and protio solvents but now the SABRE-enhanced analyte signals dominate due to the comparatively weak thermally-polarized solvent response. The SABRE approach also enables the acquisition of 13C NMR spectra of analytes at natural isotopic abundance in a single scan as evidenced by hyperpolarized 13C NMR spectra of tens of millimolar concentrations of 4-methylpyridine. Now the associated signal enhancement factors are up to 45 500 fold (P = 4.0%) and achieved in just 15 s. Integration of an automated SABRE polarization system with the benchtop NMR spectrometer framework produces renewable and reproducible NMR signal enhancements that can be exploited for the collection of multi-dimensional NMR spectra, exemplified here by a SABRE-enhanced 2D COSY NMR spectrum.

Piloting Blended Strategies To Resolve Laboratory Capacity Issues in a First-Semester General Chemistry Course

Laboratory capacity is an issue that has plagued education for more than a century. New buildings, late night classes, and virtual laboratories have offered transitory relief at great expense. Missouri University of Science and Technology is employing blended strategies to increase capacity and student success. Blended strategies expand learning workspaces so that learners conduct traditional laboratory activities in both traditional and nontraditional laboratory environments. This article focuses on the proof of concept pilot results from blending the first-semester general chemistry laboratory course, which validate the adoption of this strategy for increasing student volume.

Field vs. Laboratory Usability Evaluations: a Study on a Context Dependent Mobile Application Developed with an Agile Methodology

How usability assessment of mobile interactive applications should be conducted in the frame of agile methodologies is an open question. On the one hand, usability evaluation consumes time and resources, which can make agile methodologies lose their agile essence. On the other hand, there is a considerable debate about whether user interactions with mobile systems should be investigated in the field or in more traditional laboratory environments. This work compares the results of a field study conducted in an interactive context-dependent mobile application with performed laboratory studies. This study has allowed identifying different interaction patterns and contextual factors not likely to be simulated in laboratory environment. Integrating field evaluations in agile methodologies is consistent with the objective of improving product quality through incremental assessments.

Une interface pour utilisateur de caméra 3D employée pour enregistrer les angles des poignets lors de prestations au piano

Injuries are common over a performing musician’s career and wrist injuries are the most frequent site of pain for pianists. Although general recommendations insist on keeping wrists in a “neutral” position to avoid injury, this is rarely done in practice. Recent advances in motion capture technology may aid in raising students’ awareness of the propensity to use wrist positions outside of the recommended “neutral.” These technologies may be used to measure precise wrist positions in piano playing in order to set specific thresholds for avoiding injury. This paper discusses various advantages and limitations of motion capture technologies, including data visualization and usage within the music instrument pedagogy framework in order to define a set of requirements for an accessible motion-tracking system. A prototype of a dedicated image-processing-based system with a graphical user interface that meets these requirements is described. This system uses passive coloured markers and a standard 3D camera, encouraging use outside the traditional laboratory environment. Simple camera calibration options and basic hand tracking from aerial view images allow monitoring of wrist flexion/extension over short video recordings. Measurements are compared to flexion/extension thresholds recommended for typists to prevent carpal tunnel pressure, and moments of approaching or exceeding these thresholds are flagged to the user both in real time and in post-performance. Potential applications include monitoring the practice of short technical passages without restriction of instrument or location.

Increased biodiversity in the environment improves the humoral response of rats.

Previous studies have compared the immune systems of wild and of laboratory rodents in an effort to determine how laboratory rodents differ from their naturally occurring relatives. This comparison serves as an indicator of what sorts of changes might exist between modern humans living in Western culture compared to our hunter-gatherer ancestors. However, immunological experiments on wild-caught animals are difficult and potentially confounded by increased levels of stress in the captive animals. In this study, the humoral immune responses of laboratory rats in a traditional laboratory environment and in an environment with enriched biodiversity were examined following immunization with a panel of antigens. Biodiversity enrichment included colonization of the laboratory animals with helminths and co-housing the laboratory animals with wild-caught rats. Increased biodiversity did not apparently affect the IgE response to peanut antigens following immunization with those antigens. However, animals housed in the enriched biodiversity setting demonstrated an increased mean humoral response to T-independent and T-dependent antigens and increased levels of “natural” antibodies directed at a xenogeneic protein and at an autologous tissue extract that were not used as immunogens.

From “panic” to “critical” values: which path toward harmonization?

In the conventional “brain-to-brain loop” model, a body of evidence demonstrates that the risk of errors and patient harm is significantly decreased in processes that strictly develop inside the laboratory, whereas it remains relatively high at the beginning and at the end of the total testing process, which generally lie outside of the traditional laboratory environment [1, 2]. An increasing awareness of the need for standardizing and monitoring preanalytical activities has indeed generated positive revenues in terms of improved quality and decreased risk of errors [3]. Conversely, postanalytical processes are still more vulnerable to human error(s), noncompliance, and lack of harmonization, thus jeopardizing the quality of testing and – rather inevitably – posing serious risks for patient safety. Information technology (IT) has virtually eliminated the errors of manual data transcription, thus improving both efficiency and turnaround time between clinical laboratories and stakeholders. However, information overload can generate communication breakdowns, with delayed missed or even wrong diagnoses [4]. In postanalytical activities, critical values notification represents one of the main issues, but the complexity and importance of timely and safe delivery of this vital information require further efforts to improve harmonization throughout the process. In this issue of the journal, Zeng et al. [5] describe the results of a national survey on critical values notification in 599 Chinese institutions. The authors observed significant differences among laboratories, especially for limits and lists of the critical values as well as procedures for implementation. This reinforces the need for developing harmonization projects and developing best practice recommendations, which take into account correct definitions and terms [6, 7]. This should be achieved through projects based on consensus committees, professional groups (e.g., the ad hoc EFLM Working Group), published resources, or clinical studies. In particular, we need a general agreement on which tests and values should be considered “life-threatening”, and if – and how – we should harmonize decision levels and measurement units. Contextually, the harmonization of critical values may represent a cornerstone of educational and training process aimed to promote the culture of patient safety at medical schools. The genuine concept of “critical value”, originally described by George Lundberg [8, 9], has continued to be virtually unmodified for more than 40 years but merits some considerations. First, critical values, as already defined by Lundberg [8], identify some laboratory results that are so “extremely” abnormal and are considered life threatening because they may be associated with a significant dangerous event unless a medical action is promptly established. The term “panic value” should likewise be definitively abandoned, as Lundberg himself reasonably criticized this term because “physicians are not supposed to panic over anything” [10]. Second, “critical value” should be distinguished from “critical test”. The latter term, according to the Joint Commission, identifies all tests that require rapid communication of results, irrespective of being normal, abnormal, or critical [11]. Because this is a novel and poorly explained concept, it deserves some further explanatory discussion. A “critical test” (e.g., troponin, D-dimer, hemoglobin) implies an immediate impact on clinical decision making independently of result. Laboratory results for such tests may not be associated with a serious risk for the patient’s safety, but they require timely and safe reporting. From this point of view, although current technological equipments and IT may provide timely laboratory results with improved performances, there is the need to better define mutual duties and responsibilities. In particular, the physician who requests a critical test has the responsibility to verify the availability of the result within consensually defined times, whereas the laboratory professionals must ensure appropriate and timely reporting. Therefore, a consensus should be achieved by requesting physicians (namely those from emergency departments and intensive care units) on the reciprocal responsibilities to adopt when critical laboratory tests are requested and notified, although the list of critical tests and the notification/acknowledgment procedures may vary according to specific clinical settings and operational frameworks. The notification of critical tests should hence

Comparing Biological Motion Perception in Two Distinct Human Societies

Cross cultural studies have played a pivotal role in elucidating the extent to which behavioral and mental characteristics depend on specific environmental influences. Surprisingly, little field research has been carried out on a fundamentally important perceptual ability, namely the perception of biological motion. In this report, we present details of studies carried out with the help of volunteers from the Mundurucu indigene, a group of people native to Amazonian territories in Brazil. We employed standard biological motion perception tasks inspired by over 30 years of laboratory research, in which observers attempt to decipher the walking direction of point-light (PL) humans and animals. Do our effortless skills at perceiving biological activity from PL animations, as revealed in laboratory settings, generalize to people who have never before seen representational depictions of human and animal activity? The results of our studies provide a clear answer to this important, previously unanswered question. Mundurucu observers readily perceived the coherent, global shape depicted in PL walkers, and experienced the classic inversion effects that are typically found when such stimuli are turned upside down. In addition, their performance was in accord with important recent findings in the literature, in the abundant ease with which they extracted direction information from local motion invariants alone. We conclude that the effortless, veridical perception of PL biological motion is a spontaneous and universal perceptual ability, occurring both inside and outside traditional laboratory environments.

The use of a single inertial sensor to identify stride, step, and stance durations of running gait

Current developments in inertial sensor technology could enable the measurement of running gait outside of the traditional laboratory environment. The purpose of this research was to determine the level of agreement between an inertial sensor and infrared camera based estimates of stride, step, and stance durations across a range of running speeds. An inertial sensor was placed on the sacrum of 10 elite national standard runners, and the stride, step, and stance of running gait were compared. A total of 504 samples were collected and the running velocities stratified into three equal groups of low (10–12 km/h), medium (13–15 km/h), and high (16–19 km/h). A single inertial sensor was found to be suitable for identifying stride duration with Bland–Altman limits of agreement of 95%. The stride data showed agreement at less than 0.02 s for most limits. Agreement for step showed five of the eight upper and lower limits below 0.02 s. The largest differences between both capture methods were for stance. An average bias of 0.0008 s was found and standard error ranged between 0.0004 s and 0.0009 s across all variables. The results from this research found that inertial sensors are suitable to measure stride, step, and stance duration, and provide the opportunity to measure running gait outside of the traditional laboratory.

A Comparison of Student Performance in a Simulation Clinic and a Traditional Laboratory Environment: Three‐Year Results

With simulation clinics, dental schools have improved their preclinical laboratories to provide a more realistic clinical teaching environment. However, there is very little data to support the assumption that these facilities actually improve student performance of technical skills. This study compared the scores of two fixed preparations for full cast crowns by third-year dental students. One of the preparations was made in the simulation clinic manikin, and the other was prepared on the bench top. Three prosthodontic faculty members scored the preparations in the areas of occlusal reduction, axial reduction, resistance and retention, and margination. The study also compared the performance of three classes of dental students: one class with no experience in the simulation clinic, one with one year of experience, and one with two years of experience. The amount of time since completing the fixed prosthodontics course among the students was also evaluated. This was done because the third-year students at the University of Iowa rotate through a series often-week clerkships rather than a comprehensive care model. (Therefore, not all students start clinical prosthodontics at the same time.) In addition, all student participants completed a questionnaire that addressed their perception of their clinical readiness prior to treating their first fixed prosthodontic patient. When we compared the classes of years 1, 2, and 3 by average preparation score, we found a significant difference among the scores for teeth prepared on the bench top (p = 0.0001) but not for the teeth prepared in the mannequin (p = 0.1176). For Year 1 (no simulation clinic experience), the amount of elapsed time following completion of the fixed prosthodontic course was not significant for the tooth prepared on the bench top or in the manikin (p = 0.57113 and 0.0661). For Year 2 (one year of simulation clinic experience), the elapsed time following completion of the fixed prosthodontic course was significant for the tooth prepared on the bench top (p = 0.0482), but it was not significant for the tooth prepared in the manikin (p = 0.2968). For Year 3 (two years of simulation clinic experience), the amount of elapsed time following completion of the fixed prosthodontic course was not significant for the tooth prepared on the bench top or in the manikin (p = 0.7275 and 0.6007). The questionnaire revealed that, in general, the majority of the students perceived their clinical readiness as more than adequate. These results are mixed in that students with more bench top experience scored better on the bench top, and students with more manikin experience scored equally in both environments.