Persistent pollution of genetic materials in a typical laboratory environment.

From the onset of coronavirus disease (COVID-19) pandemic, there are concerns regarding the disease spread and environmental pollution of biohazard since studies on genetic engineering flourish and numerous genetic materials were used such as the nucleic acid test of the severe acute respiratory syndrome coronavirus (SARS-CoV-2). In this work, we studied genetic material pollution in an institute during a development cycle of plasmid, one of typical genetic materials, with typical laboratory settings. The pollution source, transmission routes, and pollution levels in laboratory environment were examined. The Real-Time quantitative- Polymerase Chain Reaction results of all environmental mediums (surface, aerosol, and liquid) showed that a targeted DNA segment occurred along with routine experimental operations. Among the 79 surface and air samples collected in the genetic material operation, half of the environment samples (38 of 79) are positive for nucleic acid pollution. Persistent nucleic acid contaminations were observed in all tested laboratories and spread in the public area (hallway). The highest concentration for liquid and surface samples were 1.92 × 108 copies/uL and 5.22 × 107 copies/cm2, respectively. Significant amounts of the targeted gene (with a mean value of 74 copies/L) were detected in the indoor air of laboratories utilizing centrifuge devices, shaking tables, and cell homogenizers. Spills and improper disposal of plasmid products were primary sources of pollution. The importance of establishing designated experimental zones, employing advanced biosafety cabinets, and implementing highly efficient cleaning systems in laboratories with lower biosafety levels is underscored. SYNOPSIS: STATEMENT. Persistent environmental pollutions of genetic materials are introduced by typical experiments in laboratories with low biosafety level.

Strategic behaviour and decision making in competitive hospital markets: an experimental investigation.

We investigate quality provision and the occurrence of strategic behaviour in competitive hospital markets where providers are assumed to be semi-altruistic towards patients. For this, we employ a laboratory experiment with a hospital market framing. Subjects decide on the quality levels for one of three competing hospitals respectively. We vary the organizational aspect of whether quality decisions within hospitals are made by individuals or teams. Realized monetary patient benefits go to real patients outside the lab. In both settings, we find that degrees of cooperation quickly converge towards negative values, implying absence of collusion and patient centred or competitive quality choices. Moreover, hospitals treat quality as a strategic complement and adjust their quality choice in the same direction as their competitors. The response magnitude for team markets is weaker; this is driven by non-cooperative or altruistic teams, which tend to set levels of quality that are strategically independent.

Experimental study on new structure teeth in a high-temperature environment.

In high-temperature drilling, especially in high-temperature geothermal drilling, cone bits often experience common and severe tooth loss. This issue significantly reduces the cone bit's service life and has a detrimental impact on drilling efficiency. The quality of the fixed teeth plays a crucial role in the performance of the cone bit. In high-temperature environments, conventional methods fail to meet the requirements for securing the cone bit's teeth. Therefore, to address the tooth loss problem in high-temperature drilling, a new tapered tooth structure is proposed. Laboratory experiments were conducted to secure teeth with varying tapers at both normal and high temperatures. The results revealed that the maximum fastening force increased progressively with the degree of taper, reaching its peak at C50. Compared to conventional cylindrical teeth, the maximum fastening force increased by approximately 88.6%-271.1% at different temperatures. The tapered structure demonstrated superior tooth-fixing strength. The maximum fastening force is the smallest at 300 °C, approximately 23.7%-61.2% lower than at normal temperature. Under the same interference conditions, the maximum fastening force increased with greater taper. With interference values of 0.075, 0.095, and 0.115, the maximum fastening force increased by 48.9%-175.1%, 14%-141.6%, and 53%-271.1%, respectively, when compared to cylindrical teeth with C300, C200, C100, and C50 tapers. The tapered structure exhibited superior tooth-fixing strength and significantly enhanced tooth retention strength at high temperatures.

Identification of soil-dwelling predators of tick nymphs (Acari: Ixodidae) by stable isotope labeling.

Ticks (Family Ixodidae) spend most of their life cycle as immature stages in the soil and litter, and as any other soil invertebrates, are likely to be controlled top-down by soil-dwelling predators. To date, the ability of soil invertebrate predators to control ixodid tick population remains little known, partly due to methodological difficulties. In the current study, we developed and successfully tested a novel method of labeling live Ixodes ricinus (L., 1758) (Ixodida: Ixodidae) nymphs with a 15N isotope label. Labeled ticks were used in a small-scale 8-day-long microcosm experiment to reveal soil predators attacking nymphs. Only a small fraction (4.1% of all samples) of soil generalist predators preyed upon nymphs. A strong 15N label was found in 5 predator species, namely 2 spiders (Pachygnatha listeri Sundevall, 1830, Tetragnathidae and Ozyptila sp., Theridiidae), 2 gamasid mites (Pergamasus beklemischevi Sellnick, 1929 and Pergamasus quisquiliarum [Canestrini, 1882], Parasitidae), and 1 staphylinid beetle (Geostiba circellaris [Gravenhorst, 1806], Staphylinidae). The isotopic labeling can be a useful tool in revealing a range of invertebrate predators that can control tick populations in soil.

Laboratory Study of Collisionless Magnetic Reconnection.

A concise review is given on the past two decades' results from laboratory experiments on collisionless magnetic reconnection in direct relation with space measurements, especially by the Magnetospheric Multiscale (MMS) mission. Highlights include spatial structures of electromagnetic fields in ion and electron diffusion regions as a function of upstream symmetry and guide field strength, energy conversion and partitioning from magnetic field to ions and electrons including particle acceleration, electrostatic and electromagnetic kinetic plasma waves with various wavelengths, and plasmoid-mediated multiscale reconnection. Combined with the progress in theoretical, numerical, and observational studies, the physics foundation of fast reconnection in collisionless plasmas has been largely established, at least within the parameter ranges and spatial scales that were studied. Immediate and long-term future opportunities based on multiscale experiments and space missions supported by exascale computation are discussed, including dissipation by kinetic plasma waves, particle heating and acceleration, and multiscale physics across fluid and kinetic scales.

Assessment of a UWB Real Time Location System for Dairy Cows' Monitoring.

In the field of precision livestock farming, many systems have been developed to identify the position of each cow of the herd individually in a specific environment. Challenges still exist in assessing the adequacy of the available systems to monitor individual animals in specific environments, and in the design of new systems. The main purpose of this research was to evaluate the performance of the SEWIO ultrawide-band (UWB) real time location system for the identification and localisation of cows during their activity in the barn through preliminary analyses in laboratory conditions. The objectives included the quantification of the errors performed by the system in laboratory conditions, and the assessment of the suitability of the system for real time monitoring of cows in dairy barns. The position of static and dynamic points was monitored in different experimental set-ups in the laboratory by the use of six anchors. Then, the errors related to a specific movement of the points were computed and statistical analyses were carried out. In detail, the one-way analysis of variance (ANOVA) was applied in order to assess the equality of the errors for each group of points in relation to their positions or typology, i.e., static or dynamic. In the post-hoc analysis, the errors were separated by Tukey's honestly significant difference at p > 0.05. The results of the research quantify the errors related to a specific movement (i.e., static and dynamic points) and the position of the points (i.e., central area, perimeter of the investigated area). Based on the results, specific information is provided for the installation of the SEWIO in dairy barns as well as the monitoring of the animal behaviour in the resting area and the feeding area of the breeding environment. The SEWIO system could be a valuable support for farmers in herd management and for researchers in the analysis of animal behavioural activities.

Endogenous reference price auctions for a diverse set of commodities: an experimental analysis.

This paper is concerned with multi-object, multi-unit auctions with a budget constrained auctioneer who has noisy value estimates for each object. We propose a new allocation mechanism, the endogenous reference price auction, with two key features. First, bids are normalized across objects using "reference prices." Second, reference prices are set endogenously using information extracted from the bids submitted. We report on an experiment showing that a simple endogenous process mitigates value inaccuracies and improves three performance measures: the seller's profit, allocative efficiency and total surplus. These results have important implications for large auctions used in practice. Supplementary Information: The online version contains supplementary material available at 10.1007/s10683-022-09783-6.

Who benefits from quality competition in health care? A theory and a laboratory experiment on the relevance of patient characteristics.

We study how competition between physicians affects the provision of medical care. In our theoretical model, physicians are faced with a heterogeneous patient population, in which patients systematically vary with regard to both their responsiveness to the provided quality of care and their state of health. We test the behavioral predictions derived from this model in a controlled laboratory experiment. In line with the model, we observe that competition significantly improves patient benefits as long as patients are able to respond to the quality provided. For those patients, who are not able to choose a physician, competition even decreases the patient benefit compared to a situation without competition. This decrease is in contrast to our theoretical prediction implying no change in benefits for passive patients. Deviations from patient-optimal treatment are highest for passive patients in need of a low quantity of medical services. With repetition, both, the positive effects of competition for active patients as well as the negative effects of competition for passive patients become more pronounced. Our results imply that competition can not only improve but also worsen patient outcome and that patients' responsiveness to quality is decisive.

Median voter dynamics in a laboratory experiment on voting over redistribution.

This paper reports results from a laboratory experiment that investigates the prevalence of median voter dynamics in the Meltzer-Richard redistribution mechanism. I focus on the model's microfoundations and analyze how individuals translate material incentives into proposed tax rates and how these individual proposals get aggregated into a collective group choice under two different voting rules; majority rule and voting by veto. My experimental results show that material incentives do not fully determine individual proposals. In addition, personal characteristics and justice attitudes constitute additional facets of individual motivations. Median voter dynamics are prevalent under both voting rules at least when looking at aggregate behavior. Both decision rules thus lead to an un-biased aggregation of voters' preferences. Moreover, the experimental results show only minor behavioral differences between decisions employing majority rule and collective choices using voting by veto.

Physician altruism under the change from pure payment system to mixed payment schemes: experimental evidence.

BACKGROUND: Mixed payment schemes have become one of the effective measures to balance medical costs and quality of medical services. However, altruism as an intrinsic motivation may influence the effect of switching from a pure payment system to mixed payment schemes. This study aimed to quantify physicians' altruism and analyze the effect of changes of payment system on physicians' altruism and thus proposed references for the reform of payment system. METHODS: We simulated an exogenous payment system in a controlled laboratory with five experimental groups and 150 medical student subjects. Physicians' altruism was measured by estimating altruistic parameter and marginal rate of substitution. The non-parametric test and the least square regression analysis were used to analyze the differences of altruistic parameters between pure payment systems and mixed payment schemes. Finally, we analyzed the effect of changes in payment system accompanied by changes in trade-off range on physicians' altruism. RESULTS: We find that the mean value of individual altruistic parameter is 0.78 and the marginal rate of substitution is 1.078. Their estimates at the individual level were significantly positively correlated (Spearman's ρ = 0.715, p < 0.01). The shift from pure payment system to mixed payment scheme reduced the altruistic parameter. However, the altruistic parameter increased with the increase of the trade-off range. Physicians who were more altruistic generated higher patients' health benefit. For each unit increase in altruistic parameter, the increase in patients' health benefit was lower in mixed payment scheme than in the pure payment system. CONCLUSION: The estimates of altruistic parameters are reliable. Physicians attach a higher weight to patients' benefit than to their own profit. Mixed payment schemes improve physicians' behavior and relate to lower altruistic parameters; physicians only need to sacrifice less personal profits to generate the same or even higher altruistic parameter as under the pure payment system. The design of mixed payment schemes that make the interests of physicians and patients close to each other by reducing the trade-off range can provide implication for the reform of payment system in which the physicians' interest and the patients' benefit are consistent.

The formation of physician altruism.

We study how patient-regarding altruism is formed by medical education. We elicit and structurally estimate altruistic preferences using experimental data from a large sample of medical students (N = 733) in Germany at different progress stages in their studies. The estimates reveal substantial heterogeneity in altruistic preferences of medical students. Patient-regarding altruism is highest for freshmen, significantly declines for students in the course of medical studies, and tends to increase again for last year students, who assist in clinical practice. Also, patient-regarding altruism is higher for females and positively associated to general altruism. Altruistic medical students have gained prior practical experience in healthcare, have lower income expectations, and are more likely to choose surgery and pediatrics as their preferred specialty.

Ingroup bias in a social learning experiment.

Does social learning and subsequent private information processing differ depending on whether the observer shares the same group identity as the predecessor whose action is observed? In this paper, we conduct a lab experiment to answer this question, in which subjects first observe a social signal and then receive a private signal. We find that subjects put greater weights on the social signal if they share with the predecessor the same group identity that is induced in the experimental environment. We also provide suggestive evidence that such an ingroup-outgroup difference cannot be explained by individuals' beliefs of the predecessor's rationality. Moreover, heterogeneous effects of group identity exist in weights given to the subsequent private signal: Compared to when the predecessor is an outgroup, those who have learned from an ingroup predecessor put a greater (smaller) weight on the private signal if it contradicts (confirms) the social signal. We conjecture that such group effects are consistent with the perspective that group identity works as a framing device and brings about certain decision heuristics in the social signal phase, which no longer exist in the private signal phase. Supplementary Information: The online version contains supplementary material available at 10.1007/s10683-022-09788-1.

Migration behaviour of LNAPL in fractures filled with porous media: Laboratory experiments and numerical simulations.

With the increasing requirement of maintaining world energy security and strategic reserves, oil storage and transportation facilities are being built at a large scale. Taking the safe and efficient operation of petroleum storage projects as the goal, a set of experimental apparatus to investigate the migration of contaminants in fractures filled with media was developed to predict and evaluate the environmental risk of oil contaminants leakage. A multiphase numerical flow model based on COMSOL was built based on the laboratory experimental model. Specifically, the migration behaviour of Light Non-aqueous Phase Liquid (LNAPL) through a sand-filled fractured medium was studied by laboratory experiments and numerical simulations. Image and chemical analyses methods were used to monitor and study LNAPL migration behaviour for varying grain sizes of porous medium filling the fractures and varying groundwater table elevations. Laboratory experimental results showed that the LNAPL migration velocity in filled fracture network was significantly faster than that in adjoining porous media during the initial stage of infiltration. The migration velocity increased with the relative permeability of filled sand, which was closely related to the Van Genuchten (VG) model parameters α and n. LNAPL migrated downward with the falling groundwater table and became entrapped with the rising groundwater table, and the amount of entrapment depended on VG model parameters. Hydrogeological parameters were calibrated and LNAPL migration in filled fractured media was predicted using the calibrated numerical model. Simulation results revealed that fracture inclination had an important influence on LNAPL migration in filled fractured media and its migration velocity decreased with a decrease in fracture inclination. These research results can be applied to the control and remediation of oil-contaminated sites in fractured rock settings, such as at underground oil storage tanks and caverns, as well as at underground oil pipelines.

Effect of salinity on valves morphology in freshwater diatoms.

Increased salt concentration is one of the most widespread problems affecting freshwater worldwide. Aquatic communities, and in particular periphytic diatoms, react to this alteration in water quality by modifying their structural parameters and physiology at the individual level, which is commonly manifested by the appearance of teratological forms. The present work presents the results of an experimental laboratory study in which a biofilm grown on artificial substrates was subjected to a gradient of water conductivities for 4 weeks. The results show an increase in the number of deformed valves over time proportionally to the increase in conductivity for each experimental treatment. These effects are also verified by analyzing the concentration of chlorophyll-a in the experimental biofilms, which demonstrate a metabolic response to the induced osmotic stress. No changes were recorded; however, in species richness or diversity of taxa present in the treatments. Our results, therefore, confirm at the experimental level numerous previous field observations about the harmful effect of salinity on periphytic diatoms, and also their ability to reintegrate with the new stress conditions.

Cryogrinding and sieving techniques as challenges towards producing controlled size range microplastics for relevant ecotoxicological tests.

The impact of microplastics (MP) has attracted much attention from the scientific community and many laboratory assessments have been made of their effects on aquatic organisms. To produce MP from real environmental plastic waste, which would enable more realistic experiments, we used plastic pearl farming equipment from French Polynesian lagoons. Here, the pearl oyster Pinctada margaritifera could encounter MP coming from their breakdown in its surrounding environment. We tested an established method based on mechanical cryogenic grinding and liquid sieving. Our desired size range was 20-60 µm, corresponding to the optimal particle size ingested by P. margaritifera. The protocol was effective, generating MP particles of 20-60 µm (∼17,000-28,000 MP µg-1), but also produced too many smaller particles. The peak in the desired size range was thus flattened by the many small particles <3 µm (∼82,000-333,000 MP µg-1; 53-70% of total analysed particles), visible at the limit of Coulter counter analysis (cut-off point: 2 µm). Laser diffraction analysis (cut-off point: 0.4 µm) provided greater detail, showing that ∼80-90% of the total analysed particles were <1 µm. Diverging particle size distributions between those expected based on sieving range and those really observed, highlight the need to perform fine-scaled particle size distribution analyses to avoid underestimating the number of small micro- and nanoplastics (MNP) and to obtain an exact estimation of the fractions produced. Size and microstructure characterization by scanning electron microscopy suggested spontaneous particle self-assembly into crystal superstructures, which is the supposed cause of the divergence we observed. Overall, our results emphasize that particle self-assembly is a technical hurdle requiring further work and highlight the specific need to finely characterize the size distribution of MNP used in ecotoxicological experiments to avoid overestimating effects.

Rewards for information provision in patient referrals: A theoretical model and an experimental test.

We study whether bonus payments for information provision can improve the information flow between physicians. A primary care physician (PCP) decides on the provision of information of varying qualities to a specialist while referring a patient. Our theoretical model, which includes altruism and loss aversion, predicts that bonus payments increase the provision of both high- and low-quality information. Running a controlled laboratory experiment we find support for this prediction. If the beneficiary of information provision receives a higher payoff than the PCP, we observe that PCPs more often pass on high-quality information when the beneficiary is a patient. If the beneficiary receives a lower payoff than the PCP, the type of the beneficiary (specialist or patient) does not affect the provision of high-quality information.

Experimental Investigation of the Failure Scenario of Various Connection Types between Thin-Walled Beam and Sandwich Panel.

The paper presents failure scenarios for various types of connections between a thin-walled beam and a sandwich panel. In addition to standard connections used in civil engineering applications, that is, self-drilling fasteners for sandwich panels, the study examined the use of bolts, blind rivets, and double-sided acrylic tape applied linearly and pointwise. The connections were subjected to the horizontal load applied with constant eccentricity with respect to the plane of the connection surface. This load arrangement simulates the behaviour of a free flange of the thin-walled beam in bending while lateral-torsional buckling occurs. In this way, the research covers the determination of the lateral stiffness of the thin-walled beam-free flange, while the other flange is connected to the sandwich panel using various connection systems.

Data-Based Statistical Analysis of Laboratory Experiments on Concrete Frost Damage and Its Implications on Service Life Prediction.

To meet the requirements of durability design for concrete suffering frost damage, several test standards have been launched. Among the various damage indexes such as deteriorated compressive strength, relative dynamic elastic modulus (RDEM), residual deformation, etc., the concept of a "Durability Factor" (DF) is proposed by many standards to define the frost resistivity of concrete against frost action based on the experimental results from standard tests. Through a review of the literature, a clear tendency of strength/RDEM decay and residual deformation increase is captured with increasing cycles of freezing and thawing. However, tests following different standards finally derive huge scattering quantitative responses of frost resistance. Based on the large database of available laboratory experiments, this study presents a statistical analysis to propose a predictable model to calculate the DF with respect to other material factors. The statistical model is believed to be more convenient for engineering applications since the time-consuming experiment is no longer needed, and it is more precise compared with that developed according to only single experimental results to cover the uncertainties and unavoidable errors in specific tests. Moreover, the formula to calculate the DF is revised into a more general form so as to be applicable for all the laboratory experiments even for those cases without fully following the standards to derive a DF value.

Competition among public good providers for donor rewards.

We present experimental evidence for decision settings where public good providers compete for endogenous rewards which are donations (transfers) offered by outside donors. Donors receive benefits from public good provision but cannot provide the good themselves. The performance of three competition mechanisms is examined in relation to the level of public good provision and transfers offered by donors. In addition to a contest where transfers received by public good providers are proportional to effort, we study two contests with exclusion from transfers, namely a winner-takes-all and a loser-gets-nothing. We compare behavior in these three decision settings to the default setting of no-contest (no-transfers). Results for this novel decision environment with endogenous transfers show that donors offer transfers (contest prizes) at similar levels across contests and contributions to the public good are not significantly different in the three contests settings, but are consistently and significantly higher in all contests compared to the setting with no-transfers. Initially, the winner-takes-all setting leads to a significantly higher increase in public good contributions compared to the other two contests; but this difference diminishes across decision rounds. Supplementary Information: The online version contains supplementary material available at 10.1007/s10683-022-09766-7.

Transport and accumulation of plastic particles on the varying sediment bed cover: Open-channel flow experiment.

Contamination of sea bottom sediments by microplastics is widely confirmed, but the reasons for its patchiness remain poorly understood. Laboratory experiments are reported where combined sets of various plastic particles, different by shape, size, density, and flexibility, were transported by the step-wise increasing open-channel flow over the bottom covered with natural sediment of increasing grain size. For every particular flow velocity, observations revealed the recurrent formation of relatively narrow retention areas, where plastic particles lingered for some time in their motion. These areas follow the line of change of the sediment type from finer to coarser grains. It is shown that contact friction drives the retention of a particle at finer sediments, while particle/sediment-grain interaction becomes of importance when particles and sediment grains are of similar sizes. The presence of this effect can be expected for a relatively wide range of natural conditions.