Soil conditions modify species diversity effects on tree functional trait expression.

Examples of positive effects of biodiversity on ecosystem functions have kept accumulating in the last two decades, and functional traits are considered suitable tools to explain their underlying mechanisms. However, traits are rarely studied at the scale where these mechanisms (e.g., complementarity) are likely to originate, that is, between two interacting individuals. In an 18-month greenhouse experiment, we investigated how species diversity (i.e., monospecific or heterospecific tree pairs) affects within-individual leaf traits expression and variation and how this effect is modified by soil conditions. While resource addition through phosphorus fertilization partly strengthened the diversity effects, inoculation of soil microbiota (potentially leading to increased resource accessibility) resulted in counter effects. Hence, in contrast to our expectations, we did not find synergistic effects of the two soil treatments, but we found distinct effects on species following an acquisitive or conservative growth strategy. Overall, our study showed that the effect of species diversity on young trees' adaptability and resource-use strategy needs to be considered alongside soil biotic and abiotic aspects. The influence of soil conditions on species diversity effects is essential to understand mechanisms behind complementarity at the individual level, which ultimately translate to the community scale.

Outcomes of genital hygiene and anxiety training for mothers of girls with profound intellectual disabilities: A randomized controlled experiment.

Female children with profound intellectual disabilities (IDs) may experience symptoms of urinary tract infections (UTIs) and depend on others' care. However, their caregivers may lack general hygiene skills and experience heightened anxiety when their care is expected. This study reports outcome of a training that aims to enhance genital hygiene skills and decrease anxiety levels of mothers of girls diagnosed with profound ID. The study was conducted in a city located in Turkey in 2020. It was designed with a randomized controlled experimental approach based on a pre-test and post-test model with experimental and control groups. The sample consisted of 66 mothers of girls who were diagnosed with profound ID, did not have UTI but were at high risk of developing it. A 6-week program with 24 sessions was implemented. After the training, mothers in the experimental group changed the sanitary pad and the underwear during menstruation and gave their daughters a bath more frequently; had a higher knowledge of recognizing and preventing UTI symptoms and cleaning of the perineum area; and had significantly lower levels of anxiety. A carefully designed simulator-based training can enhance the knowledge and skills of mothers to recognize the UTI symptoms, apply their knowledge to prevent the symptoms and implement genital hygiene practices, which in turn have a positive effect on reducing their level of anxiety.

The Effect of Spring Barley Fertilization on the Content of Polycyclic Aromatic Hydrocarbons, Microbial Counts and Enzymatic Activity in Soil.

Soil-dwelling microorganisms play an important role in the environment by decomposing organic matter, degrading toxic compounds and participating in the nutrient cycle. The microbiological properties of soil are determined mainly by the soil pH, granulometric composition, temperature and organic carbon content. In agricultural soils, these parameters are modified by agronomic operations, in particular fertilization. Soil enzymes participate in nutrient cycling and they are regarded as sensitive indicators of microbial activity and changes in the soil environment. The aim of the present study was to determine whether PAH content in soil is associated with the microbial activity and biochemical properties of soil during the growing season of spring barley treated with manure and mineral fertilizers. Soil samples for analysis were collected on four dates in 2015 from a long-term field experiment established in 1986 in Balcyny near Ostróda (Poland). The total content of PAHs was lowest in August (194.8 µg kg-1) and highest in May (484.6 µg kg-1), whereas the concentrations of heavier weight PAHs was highest in September (158.3 µg kg-1). The study demonstrated that weather conditions and microbial activity induced considerable seasonal variations in PAHs content. Manure increased the content of organic carbon and total nitrogen, the abundance of organotrophic, ammonifying and nitrogen-fixing bacteria, actinobacteria and fungi and enhanced the activity of soil enzymes, including dehydrogenases, catalase, urease, acid phosphatase and alkaline phosphatase.

Does the mainland China-Hong Kong exchange program change the views of local university students in Hong Kong on regional cooperation? A randomized control-group pre-test post-test experiment.

The Chinese central government has been running an intensive exchange program called the Mainland China-Hong Kong Ten Thousand Student Exchange Program since 2012 to support local Hong Kong university students' visits to mainland China, with the aim of promoting exchange and regional cooperation between Hong Kong and mainland China. However, little is known about local Hong Kong university students' views on regional cooperation and whether the program is effective in changing their views. Using a randomized experimental design, we find that most students hold positive views on regional cooperation between Hong Kong and mainland China, but a considerable percentage of students oppose integration with mainland China. We also find that the program is effective in positively changing students' views on certain aspects of regional cooperation related to the free trade zones and the Hong Kong-Zhuhai-Macau Bridge, but is not significantly effective on other aspects of regional cooperation. This study provides the first causal quantitative evidence regarding the impact of the mainland China-Hong Kong exchange program on local university students' views regarding regional cooperation. The findings help inform the public about the prospect of regional cooperation and offer policy implications on youth exchange between mainland China and Hong Kong.

Decomposition Characteristics of Lignocellulosic Biomass in Subtropical Rhododendron Litters under Artificial Regulation.

The nutrient turnover of subtropical rhododendron forests is slow, natural regeneration is difficult, and the decomposition of litter is slow. Lignin, cellulose, and hemicellulose are the key factors affecting the decomposition rate of litters. In this study, the litters of three forest stands, namely evergreen broadleaf Rhododendron delavayi, evergreen broadleaf Rhododendron agastum, and deciduous broadleaf mixed forest, were taken as the research objects to explore the dynamic changes and effects of lignin, cellulose, and hemicellulose contents in litters of different stands under indoor artificial control measures. Exogenous nitrogen, phosphorus, alkaline substances, and microbial agents were added to decompose litters in the laboratory for 140 days. Our results showed that (1) the contents of lignin and cellulose in the litters of the three stands decreased significantly in the early stage of decomposition and the content of hemicellulose was stable, and (2) low concentrations of nitrogen and phosphorus can accelerate the degradation of lignin, cellulose, and hemicellulose in litters of the three stands and thus promote the decomposition of litters. This study provides basic data for the nutrient return of artificial intervention in subtropical rhododendron forests in China.

The restorative effects of short-term exposure to nature in immersive virtual environments (IVEs) as evidenced by participants' brain activities.

Short-term exposure to nature has excellent potential to be used as a public health intervention measure. Nevertheless, the physiological and psychological mechanisms of this health benefit are still unclear. In this study, we intend to verify the effects of short-term exposure to nature on psychological functioning and to explore the underlying mechanism through experiments conducted in immersive virtual environments (IVEs). Participants were randomly exposed to videos of an urban forest and an indoor environment in IVEs. Before and after the exposure, a participant's self-perceived stress and cognitive performance were measured using the PSS-14 form and the Stroop task, respectively. Their brain activities during the exposure were measured using the electroencephalogram (EEG). The PSS-14 and the Stroop task results confirmed the benefits of stress reduction and cognitive performance improvements from short-term nature exposure. At the same time, rhythmic brain activities during nature exposure indicated better attentional states. The electrodes around the parietal region detected significantly stronger power spectral density of the theta band than other bands. Also, participants showed high functional connectivity among different brain parts during nature exposure, which revealed better cognitive flexibility. The topographic pattern of the differences in functional connectivity overlapped well with the default mode network (DMN)-a "task-negative" network active during the resting state. The overlap indicated a lower cognitive processing load when exposing to nature. Our results support the hypothesis that nature's restorative effects mainly come from effortless processing in natural environments.

Low temperature and short daylength interact to affect the leaf senescence of two temperate tree species.

Temperature and photoperiod are two major environmental cues shaping the leaf senescence of temperate tree species. However, how the control of leaf senescence is split between photoperiod and temperature is unknown for many ecologically important species. Here, we conducted a growth chamber experiment to test the effects of temperature (6, 9, 18 and 21°C) and photoperiod (8 and 16 h daylength) on leaf senescence of two temperate tree species (Quercus mongolica Fisch. and Larix principis-rupprechtii Mayr.) distributed in montane forest of China. The results showed that low temperature (LT) alone could induce leaf senescence of both species under long daylength (LD) conditions, but the leaf senescence of L. principis-rupprechtii was more sensitive to the decrease in temperature than that of Q. mongolica under the LD condition. Short daylength (SD) alone could only induce the leaf senescence of L. principis-rupprechtii, suggesting that the photoperiod sensitivity varies between species. SD could accelerate the LT-induced senescence, but the effect of SD reduced with the decrease in temperature. Based on these findings, we developed a new autumn phenology model by incorporating interspecific differences in the photoperiod sensitivity of leaf senescence. Compared with the three existing process-based autumn phenology models, the new model was more robust in simulating the experimental data. When employing these models to available long-term phenological data, our new model also performed best in reproducing the observed leaf senescence date of two closely related species (Quercus robur L. and Larix decidua Mill.). These results enhance our understanding of how LT and SD control leaf senescence. The prediction of the climate change impacts on forest carbon uptake could be improved by incorporating this new autumn phenological model into the terrestrial biosphere models.

Secondary Outcomes of a Front-of-Pack-Labelling Randomised Controlled Experiment in a Representative British Sample: Understanding, Ranking Speed and Perceptions.

Front-of-pack labels (FOPLs) provide simplified nutritional information that aims to inform consumer choice and encourage reformulation. We conducted an online randomised controlled experiment on a representative British sample to test the effectiveness of FOPLs across a range of outcomes. The primary outcomes have been published; here, we present the secondary outcomes: the ability to rank the healthiest product and the time to complete the rankings by comparing the FOPL groups and a no-label control, as well as a descriptive analysis of the perceptions. Participants from the NatCen panel were randomised to one of five experimental groups (Multiple Traffic Lights; Nutri-Score; Warning Label; Positive Choice tick; no-label control). Six food/drink categories were selected (pizza, drinks, cakes, crisps, yoghurts, breakfast cereals), and three products were created with varying healthiness. The participants (analytic sample = 4530) were asked to rank the products in order of healthiness twice (baseline: no label; follow-up: experimental group label). Compared to the control, the probability of correctly ranking the healthiest product at follow-up was significantly greater for the N-S, MTL and WL across all products. The time to correctly complete the ranking was fastest for the N-S, PC and no-label control. The descriptive analysis showed that the FOPLs were perceived favourably, and especially N-S and MTL. The findings were supportive of the primary analyses, with those results suggesting that N-S performed the best, and then MTL.

Biomass Allocation and Leaf Morphology of Saplings Grown under Various Conditions of Light Availability and Competition Types.

Plant growth is almost always limited by light availability and competition. However, plants are generally plastic and can change their morphology and biomass allocation to optimize growth under suboptimal conditions. We set up a controlled pot experiment with three light availability levels (10%, 20%, and 50%) to study the effect of light and competition on the biomass allocation and leaf morphology in monospecific and mixed pots of recently planted European beech (Fagus sylvatica L.), Norway spruce (Picea abies (L.) Karst.), and Douglas fir (Pseudotsuga menziesii (Mirb.) Franco) saplings using a quantile regression model. Specific leaf area (SLA) showed the strongest reaction and increased with decreasing light availability. Woody aboveground mass fraction (AMF) increased with decreasing light availability, but the effect of light on biomass allocation was less pronounced than on SLA. The SLA, woody AMF, and root mass fraction (RMF) of the two conifer species and European beech varied greatly, with European beech having a higher SLA and RMF than the two conifer species. The associated effect of plant size on biomass allocation was small, and the strength of the association was not meaningful on a practical level. The competitor's effect on biomass allocation was minor overall and only present for some species, suggesting that species' functional dissimilarity does not greatly affect allocational patterns in early tree development stages.

Are models better read on paper or on screen? A comparative study.

Is it really better to print everything, including software models, or is it better to view them on screen? With the ever increasing complexity of software systems, software modeling is integral to software development. Software models facilitate and automate many activities during development, such as code and test case generation. However, a core goal of software modeling is to communicate and collaborate. Software models are presented to team members on many mediums and two of the most common mediums are paper and computer screens. Reading from paper or screen is ostensibly considered to have the same effect on model comprehension. However, the literature on text reading has indicated that the reading experiences can be very different which in turn effects various metrics related to reader performance. This paper reports on an experiment that was conducted to investigate the effect of reading software models on paper in comparison with reading them on a computer screen with respect to cognitive effectiveness. Cognitive effectiveness here refers to the ease by which a model reader can read a model. The experiment used a total of 74 software engineering students as subjects. The experiment results provide strong evidence that displaying diagrams on a screen allows subjects to read them quicker. There is also evidence that indicates that on screen viewing induces fewer reading errors.

Histopathological effects of short-term aqueous exposure to environmentally relevant concentration of lead (Pb) in shorthorn sculpin (Myoxocephalus scorpius) under laboratory conditions.

Shorthorn sculpin (Myoxocephalus scorpius) has been used as a sentinel species for environmental monitoring, including heavy metal contamination from mining activities. Former lead-zinc (Pb-Zn) mines in Greenland resulted in elevated concentrations of metals, especially Pb, in marine biota. However, the potential accumulation of Pb and effects of the presence of Pb residues in fish on health of sculpins observed in the field have not been validated in laboratory experiments. Therefore, our aim was to validate field observation of shorthorn sculpin via controlled laboratory exposure to environmentally relevant concentrations of dissolved Pb. We evaluated the effects of a short-term (28 days) exposure to Pb on Pb residues in sculpin blood, gills, liver, and muscle and the morphology of gills and liver. The highest level of Pb was found in the gills, followed by muscle and then liver. Pb levels in liver, gills, and blood of Pb-exposed sculpins were significantly higher than those in control fish, showing that blood is suitable for assessing Pb accumulation and exposure in sculpins. Histopathological investigations showed that the severity score of liver necrosis and gill telangiectasia of Pb-exposed sculpins was significantly greater than in control fish. The number of mucous cells in gills was positively correlated with Pb concentrations in organs. Overall, the results validated field observation for the effects of Pb on wild sculpin and contributed to the improved use of the shorthorn sculpin as sentinel species for monitoring contamination from Pb mines in the Arctic.

Assessing the Effectiveness of Front of Pack Labels: Findings from an Online Randomised-Controlled Experiment in a Representative British Sample.

Front of pack food labels (FOPLs) provide accessible nutritional information to guide consumer choice. Using an online experiment with a large representative British sample, we aimed to examine whether FOPLs improve participants' ability to identify the healthiness of foods and drinks. The primary aim was to compare ability to rank between FOPL groups and a no label control. Adults (≥18 years), recruited from the NatCen panel, were randomised to one of five experimental groups (Multiple Traffic Light, MTL; Nutri-Score, N-S; Warning Label, WL; Positive Choice tick, PC; no label control). Stratification variables were year of recruitment to panel, sex, age, government office region, and household income. Packaging images were created for three versions, varying in healthiness, of six food and drink products (pizza, drinks, cakes, crisps, yoghurts, breakfast cereals). Participants were asked to rank the three product images in order of healthiness. Ranking was completed on a single occasion and comprised a baseline measure (with no FOPL), and a follow-up measure including the FOPL as per each participant's experimental group. The primary outcome was the ability to accurately rank product healthiness (all products ranked correctly vs. any incorrect). In 2020, 4504 participants had complete data and were included in the analysis. The probability of correct ranking at follow-up, and improving between baseline and follow-up, was significantly greater across all products for the N-S, MTL and WL groups, compared to control. This was seen for only some of the products for the PC group. The largest effects were seen for N-S, followed by MTL. These analyses were adjusted for stratification variables, ethnicity, education, household composition, food shopping responsibility, and current FOPL use. Exploratory analyses showed a tendency for participants with higher compared to lower education to rank products more accurately. Conclusions: All FOPLs were effective at improving participants' ability to correctly rank products according to healthiness in this large representative British sample, with the largest effects seen for N-S, followed by MTL.

Impacts of growth form and phylogenetic relatedness on seed germination: A large-scale analysis of a subtropical regional flora.

Plant regeneration strategy plays a critical role in species survival and can be used as a proxy for the evolutionary response of species to climate change. However, information on the effects of key plant traits and phylogenetic relatedness on seed germination is limited at large regional scales that vary in climate. To test the hypotheses that phylogenetic niche conservatism plays a critical force in shaping seed ecophysiological traits across species, and also drives their response to climatic fluctuation, we conducted a controlled experiment on seed germination and determined the percentage and rate of germination for 249 species in subtropical China under two temperature regimes (i.e., daily 25°C; daily alternating 25/15°C for each 12 hr). Germination was low with a skewed distribution (mean = 38.9% at 25°C, and 43.3% at 25/15°C). One fifth of the species had low (<10%) and slow (4-30 days) germination, and only a few (8%) species had a high (>80%) and rapid (1.2-6.6 days) germination. All studied plant traits (including germination responses) showed a significant phylogenetic signal, with an exception of seed germination percentage under the alternating temperature scenario. Generalized linear models (GLMs) and phylogenetic generalized estimation equations (GEEs) demonstrated that growth form and seed dispersal mode were strong drivers of germination. Our experimental study highlights that integrating plant key traits and phylogeny is critical to predicting seed germination response to future climate change.

Effects on Some Therapeutical, Biochemical, and Immunological Parameters of Honey Bee (Apis mellifera) Exposed to Probiotic Treatments, in Field and Laboratory Conditions.

Several negative factors contribute to a decline in the number of insect pollinators. As a novel approach in therapy, we hypothesize that the EM® for bees could potentially have an important therapeutic and immunomodulatory effect on honey bee colonies. The aim of our study was to evaluate its impact on honey bees at the individual and colony level. This is the first appliance of the commercial probiotic mix EM® PROBIOTIC FOR BEES in honey bees as economically important social insects. The sugar syrup with 10% of probiotic was administered by spraying or feeding the honey bee colonies in the field conditions, in order to evaluate the infection levels with spores of Nosema spp. and colonies' strength. Moreover, in laboratory-controlled conditions, in the hoarding cages, adult workers have been fed with sugar syrup supplemented with 2.5, 5, and 10% of EM® for bees for biochemical and immunological analyses of hemolymph, and with 5 and 10% for measuring the size of hypopharyngeal glands. It was found that following the EM® for bees administration the Nosema spp. spore counts in colonies were significantly reduced, and colonies' strength was increased. The results at the individual level showed significant positive physiological changes in treated groups of adult bees, revealing at the same time a higher mortality rate when feeding sugar syrup supplemented with the probiotic.

The Influence of the New US Nutrition Facts Label on Consumer Perceptions and Understanding of Added Sugars: A Randomized Controlled Experiment.

BACKGROUND AND OBJECTIVES: This study assessed the effects of the new Nutrition Facts label (NFL) compared with the current NFL on consumer purchase intentions and understanding of added sugars, and differences by educational attainment. DESIGN: Randomized controlled online experiment. PARTICIPANTS/SETTING: Final study sample of 1,156 US adults, oversampling participants with low education. INTERVENTION: All participants were exposed to a control condition (images of bread, 100% juice, yogurt, and canned fruit with no NFL) and then randomized to one of two label conditions: the current NFL with information on total sugars only or the new NFL with information on added sugars. Participants responded to the same set of questions in the control and the label conditions while viewing products that displayed one of the two NFLs. MAIN OUTCOME MEASURES: Differences in scores averaged across all products for understanding of added sugars (proportion of correctly answered multiple-choice questions) and purchase intentions (5-point Likert scale ranging from extremely likely to extremely unlikely). STATISTICAL ANALYSES PERFORMED: One-way analysis of variance was used to test for differences between NFLs. RESULTS: Compared with the current NFL, participants in the new NFL arm had better understanding of added sugars content (P<0.01). Although no significant differences were seen for purchase intentions overall, there were differences for individual products. Participants in the new NFL arm were more likely to purchase the juice (P<0.01) and less likely to buy the bread (P<0.01) compared with participants in the current NFL arm. There were no differences by educational attainment. CONCLUSIONS: Participants were better able to locate and extract added sugars information when viewing the new NFL compared with the current NFL. The new NFL may increase intent to purchase products low in added sugars but high in refined carbohydrates-an unintended consequence that warrants further study.

Raw material optimization and stone tool engineering in the Early Stone Age of Olduvai Gorge (Tanzania).

For more than 1.8 million years hominins at Olduvai Gorge were faced with a choice: whether to use lavas, quartzite or chert to produce stone tools. All are available locally and all are suitable for stone tool production. Using controlled cutting tests and fracture mechanics theory we examine raw material selection decisions throughout Olduvai's Early Stone Age. We quantify the force, work and material deformation required by each stone type when cutting, before using these data to compare edge sharpness and durability. Significant differences are identified, confirming performance to depend on raw material choice. When combined with artefact data, we demonstrate that Early Stone Age hominins optimized raw material choices based on functional performance characteristics. Doing so flexibly: choosing raw materials dependent on their sharpness and durability, alongside a tool's loading potential and anticipated use-life. In this way, we demonstrate that early lithic artefacts at Olduvai Gorge were engineered to be functionally optimized cutting tools.

Endogenetic structure of filter bubble in social networks.

The filter bubble is an intermediate structure to provoke polarization and echo chambers in social networks, and it has become one of today's most urgent issues for social media. Previous studies usually equated filter bubbles with community structures and emphasized this exogenous isolation effect, but there is a lack of full discussion of the internal organization of filter bubbles. Here, we design an experiment for analysing filter bubbles taking advantage of social bots. We deployed 128 bots to Weibo (the largest microblogging network in China), and each bot consumed a specific topic (entertainment or sci-tech) and ran for at least two months. In total, we recorded about 1.3 million messages exposed to these bots and their social networks. By analysing the text received by the bots and motifs in their social networks, we found that a filter bubble is not only a dense community of users with the same preferences but also presents an endogenetic unidirectional star-like structure. The structure could spontaneously exclude non-preferred information and cause polarization. Moreover, our work proved that the felicitous use of artificial intelligence technology could provide a useful experimental approach that combines privacy protection and controllability in studying social media.

Warming Treatment Methodology Affected the Response of Plant Ecophysiological Traits to Temperature Increases: A Quantitive Meta-Analysis.

Global mean temperature is expected to significantly increase by the end of the twenty-first century and could have dramatic impacts on a plant's growth, physiology, and ecosystem processes. Temperature manipulative experiments have been conducted to understand the responsive pattern of plant ecophysiology to climate warming. However, it remains unknown how different methodology used in these experiments will affect plants ecophysiological responses to warming. We conducted a comprehensive meta-analysis of the warming manipulative studies to synthesize the ecophysiological traits responses to warming treatment of different intensities, durations, and conducted for different species and under different experimental settings. The results indicated that warming enhanced leaf dark respiration (Rd) and specific leaf area (SLA) but decreased net photosynthetic rate (Anet) and leaf nitrogen content (LN). The positive and negative effects of warming on Rd and Anet were greater for C4 species than C3 species, respectively. The negative effect of warming treatment on Anet and LN and the positive effect on Rd were more evident under >1 year warming treatment. Negative effects of warming were more evident for plants grown at <10 L pots when experiment duration was longer than 1 year. The magnitude of warming treatment had a significant impact on most of the parameters that were investigated in the study. Overall, the results showed that warming effects on plant ecophysiological traits varied among different response variables and PFTs and affected by the magnitude of temperature change and experimental methodology. The results highlight the need for cautiously selecting the values of plant ecophysiological parameters in forecasting ecosystem function changes in future climate regimes and designing controlled experiments to realistically reflecting ecosystems responses to future global warming.

Good safety practice in a randomized controlled trial (CadColdEx) involving increased cardiac workload in patients with coronary artery disease.

BACKGROUND: Methodological information acknowledging safety of cardiac patients in controlled medical experiments are lacking. The descriptive report presents one good practice for considering safety in a randomized controlled study involving augmented cardiovascular strain among persons with coronary artery disease (CAD). METHODS: The patients were pre-selected by a cardiologist according to strictly defined selection criteria. Further confirmation of eligibility included screening of health. In addition, assessments of physical capacity by a graded bicycle ergometer test were implemented and safety monitored by an exercise physiologist and medical doctor. In this context, an emergency simulation was also carried out. A total of 18 CAD patients each underwent four different experimental interventions where either temperature (+ 22 °C and - 15 °C) and the level of exercise (rest and brisk walking) were employed for 30 min in random order (72 experiments). Baseline (20 min) and follow-up (60 min) measurements were conducted resting at + 22 °C. ECG, and brachial blood pressure were measured and perceived exertion and symptoms of chest pain inquired throughout the experiments. An emergency nurse was responsible for the health monitoring and at least two persons followed the patient throughout the experiment. A medical doctor was available on call for consultation. The termination criteria followed the generally accepted international guidelines for exercise testing and were planned prior to the experiments. RESULTS: The exercise test simulation revealed risks requiring changes in the study design and emergency response. The cardiovascular responses of the controlled trials were related to irregular HR, ST-depression or post-exercise hypotension. These were expected and the majority could be dealt on site by the research personnel and on call consultation. Only one patient was encouraged to seek for external health care consultation. CONCLUSIONS: Appropriate prospective design is a key to safe implementation of controlled studies involving cardiac patients and stimulation of cardiovascular function. This includes careful selection of participants, sufficient and knowledgeable staff, as well as identifying possible emergency situations and the required responses. TRIAL REGISTRATION: ClinicalTrials ID: NCT02855905 .

The effects of change decomposition on code review-a controlled experiment.

BACKGROUND: Code review is a cognitively demanding and time-consuming process. Previous qualitative studies hinted at how decomposing change sets into multiple yet internally coherent ones would improve the reviewing process. So far, literature provided no quantitative analysis of this hypothesis. AIMS: (1) Quantitatively measure the effects of change decomposition on the outcome of code review (in terms of number of found defects, wrongly reported issues, suggested improvements, time, and understanding); (2) Qualitatively analyze how subjects approach the review and navigate the code, building knowledge and addressing existing issues, in large vs. decomposed changes. METHOD: Controlled experiment using the pull-based development model involving 28 software developers among professionals and graduate students. RESULTS: Change decomposition leads to fewer wrongly reported issues, influences how subjects approach and conduct the review activity (by increasing context-seeking), yet impacts neither understanding the change rationale nor the number of found defects. CONCLUSIONS: Change decomposition reduces the noise for subsequent data analyses but also significantly supports the tasks of the developers in charge of reviewing the changes. As such, commits belonging to different concepts should be separated, adopting this as a best practice in software engineering.