Spoilage Microbiota of Beef Throughout Various Phases of Processing

ObjectivesThis study aimed to evaluate the spoilage microbiota of beef throughout various processing steps and identify key differences in the microbiome associated with each phase of processing.Materials and MethodsIn each of three replicates, products representing each phase of processing were made from the same uniform meat block (beef shoulder clods): T1-ground beef; T2-fresh sausage; T3-cooked links; T4-beef franks; T5-sliced bologna; T6-bologna with HPP treatment; T7-bologna with lactate/diacetate. Raw treatments were evaluated every 3 d for 21 d, and cooked treatments were evaluated every 14 d for 112 d. Heat treated products were cooked to an internal temperature of 71°C and chilled overnight at 4°C. Parameters for HPP were 600 MPa for 3 min. Aerobic (APC), anaerobic (AnPC), lactic acid bacteria (LAB), and psychrotrophic (PPC) plate counts were measured. Microbial communities were evaluated using high throughput 16S rRNA gene sequencing on the Illumina MiSeq platform. Reads were processed using QIIME, binned into operational taxonomic units (OTUs) at 97% similarity, and assigned taxonomy using the Greengenes database as reference. Alpha and β diversity of bacterial communities were analyzed using QIIME and R. Alpha diversity was estimated using observed OTUs and Chao1 estimates, and β diversity was determined using the weighted and unweighted UniFrac distance matrices (Fig. 2). Raw and cooked samples were analyzed independently for plate counts and α diversity.ResultsThere was a treatment by storage time interaction for AnPC in cooked samples (P = 0.003), where T3, T4, and T7 increased from Day 28 and 42. In raw samples, there was a main effect of storage time on APC, AnPC, LAB, and PPC (P < 0.001), where growth increased over time. In cooked samples, there was a main effect of storage time on APC, LAB, and PPC, and a main effect of treatment for APC and LAB (P < 0.030). Higher APC and LAB counts were observed in T5, while a general increase in APC, LAB, and PPC was seen throughout storage time. There were main effects of treatment and storage time on Chao1 and Observed OTUs in raw samples (P < 0.023) and a main effect of treatment in cooked samples (P < 0.009). In raw samples, bacterial richness was greater in T2 compared to T1, and generally decreased throughout storage time. In cooked samples, richness was the greatest in T3 and T4, the least in the T5, and T6 and T7 were intermediate. There were main effects for treatment and storage time on the bacterial community structure according to the weighted UniFrac distance matrix (P < 0.004) and a treatment by storage time interaction for the unweighted UniFrac distance matrix (P = 0.031). For the weighted UniFrac, T1 and T5 samples formed a cluster relatively separate from the other treatments, while T2 formed an additional cluster by itself. For the unweighted UniFrac, T1, T2, and T5 formed a cluster separate from the other samples, with increased storage times being further separated from the other samples.ConclusionResults from this study indicate that the microbiota of cooked, sliced, bologna is somewhat similar to that of raw ground beef, whereas fresh sausage, cooked links, and bologna with HPP and antimicrobial treatments are different from the former. Treatments where microbial growth was reduced had a significantly different microbial composition compared to those with greater amounts of growth.Figure 2PCoA Plot of Weighted (a) and Unweighted (b) UniFrac Distance Matrices.

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A Sequential Multiple Assignment Randomized Trial (SMART) study of medication and CBT sequencing in the treatment of pediatric anxiety disorders

BMC Psychiatry ◽

10.1186/s12888-021-03314-y ◽

2021 ◽

Vol 21 (1) ◽

Author(s):

Bradley S. Peterson ◽

Amy E. West ◽

John R. Weisz ◽

Wendy J. Mack ◽

Michele D. Kipke ◽

...

Keyword(s):

Anxiety Disorder ◽

Anxiety Disorders ◽

Randomized Trial ◽

The Other ◽

Smart Study ◽

Main Effect ◽

Multiple Assignment ◽

Stage 1 ◽

Main Effects ◽

Treatment Sequences

Abstract Background Treatment of a child who has an anxiety disorder usually begins with the question of which treatment to start first, medication or psychotherapy. Both have strong empirical support, but few studies have compared their effectiveness head-to-head, and none has investigated what to do if the treatment tried first isn’t working well—whether to optimize the treatment already begun or to add the other treatment. Methods This is a single-blind Sequential Multiple Assignment Randomized Trial (SMART) of 24 weeks duration with two levels of randomization, one in each of two 12-week stages. In Stage 1, children will be randomized to fluoxetine or Coping Cat Cognitive Behavioral Therapy (CBT). In Stage 2, remitters will continue maintenance-level therapy with the single-modality treatment received in Stage 1. Non-remitters during the first 12 weeks of treatment will be randomized to either [1] optimization of their Stage 1 treatment, or [2] optimization of Stage 1 treatment and addition of the other intervention. After the 24-week trial, we will follow participants during open, naturalistic treatment to assess the durability of study treatment effects. Patients, 8–17 years of age who are diagnosed with an anxiety disorder, will be recruited and treated within 9 large clinical sites throughout greater Los Angeles. They will be predominantly underserved, ethnic minorities. The primary outcome measure will be the self-report score on the 41-item youth SCARED (Screen for Child Anxiety Related Disorders). An intent-to-treat analysis will compare youth randomized to fluoxetine first versus those randomized to CBT first (“Main Effect 1”). Then, among Stage 1 non-remitters, we will compare non-remitters randomized to optimization of their Stage 1 monotherapy versus non-remitters randomized to combination treatment (“Main Effect 2”). The interaction of these main effects will assess whether one of the 4 treatment sequences (CBT➔CBT; CBT➔med; med➔med; med➔CBT) in non-remitters is significantly better or worse than predicted from main effects alone. Discussion Findings from this SMART study will identify treatment sequences that optimize outcomes in ethnically diverse pediatric patients from underserved low- and middle-income households who have anxiety disorders. Trial registration This protocol, version 1.0, was registered in ClinicalTrials.gov on February 17, 2021 with Identifier: NCT04760275.

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Systematic Bias Introduced by Genomic DNA Template Dilution in 16S rRNA Gene-Targeted Microbiota Profiling in Human Stool Homogenates

mSphere ◽

10.1128/msphere.00560-17 ◽

2018 ◽

Vol 3 (2) ◽

Cited By ~ 7

Author(s):

Francesco Multinu ◽

Sean C. Harrington ◽

Jun Chen ◽

Patricio R. Jeraldo ◽

Stephen Johnson ◽

...

Keyword(s):

16S Rrna ◽

16S Rrna Gene ◽

Genomic Dna ◽

Rrna Gene ◽

Microbial Composition ◽

Unifrac Distance ◽

Β Diversity ◽

Unweighted Unifrac ◽

Stool Samples ◽

Community Representation

ABSTRACT Variability in representation of microbial communities can be caused by differences in microbial composition or artifacts introduced at sample collection or processing. Alterations in community representation introduced by variations in starting DNA concentrations have not been systematically investigated in stool samples. The goal of this study was to evaluate the effect of the genomic DNA (gDNA) concentration in the resulting 16S rRNA gene library composition and compare its effect to other sample processing variables in homogenized human fecal material. Compared to a gDNA input of 1 ng/μl, inputs of ≤1.6 × 10 −3 ng/μl resulted in a marked decrease in the concentration of the 16S rRNA gene amplicon ( P < 0.001). Low gDNA concentrations (≤1.6 × 10 −3 ng/μl) were also associated with a decrease ( P < 0.001) in the number of operational taxonomic units and significant divergence in β-diversity profiles (unweighted UniFrac distance, P < 0.001), as characterized by an overestimation of Proteobacteria and underestimation of Firmicutes . Even a gDNA concentration of 4 × 10 −2 ng/μl showed a significant impact on the β-diversity profile (unweighted UniFrac distance, P = 0.03). Overall, the gDNA concentration explained 22.4% to 38.1% of the microbiota variation based on various β-diversity measures ( P < 0.001). By comparison, the DNA extraction methods and PCR volumes tested did not significantly affect the microbial composition profile, and the PCR cycling method explained less than 3.7% of the microbiota variation (weighted UniFrac distance, P = 0.03). The 16S rRNA gene yield and the microbial community representation of human homogenized stool samples are significantly altered by gDNA template concentrations of ≤1.6 × 10 −3 ng/μl. In addition, data from studies with a gDNA input of ≤4 × 10 −2 ng/μl should be interpreted with caution. IMPORTANCE The genomic DNA input for stool samples utilized for microbiome composition has not been determined. In this study, we determined the reliable threshold level under which conclusions drawn from the data may be compromised. We also determined the type of microbial bias introduced by less-than-ideal genomic input.

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A Rarefaction-Without-Resampling Extension of PERMANOVA for Testing Presence-Absence Associations in The Microbiome

10.21203/rs.3.rs-774776/v1 ◽

2021 ◽

Author(s):

Yi-Juan Hu ◽

Glen A. Satten

Keyword(s):

Distance Matrix ◽

Stochastic Approach ◽

Total Sample ◽

R Package ◽

Library Size ◽

Unique Challenge ◽

Unifrac Distance ◽

New Approach ◽

Unweighted Unifrac ◽

Inflammatory Bowel

Abstract Background PERMANOVA [1] is currently the most commonly used method for testing community-level hypotheses about microbiome associations with covariates of interest. PERMANOVA can test for associations that result from changes in which taxa are present or absent by using the Jaccard or unweighted UniFrac distance. However, such presence-absence analyses face a unique challenge: confounding by library size (total sample read count), which occurs when library size is associated with covariates in the analysis. It is known that rarefaction (subsampling to a common library size) controls this bias, but at the potential costs of information loss and the introduction of a stochastic component into the analysis.Methods Here we develop a non-stochastic approach to PERMANOVA presence-absence analyses that aggregates information over all potential rarefaction replicates without actual resampling, when the Jaccard or unweighted UniFrac distance is used. We compare this new approach to three possible ways of aggregating PERMANOVA over multiple rarefactions obtained from resampling: averaging the distance matrix, averaging the (element-wise) squared distance matrix, and averaging the F-statistic.Results Our simulations indicate that our non-stochastic approach is robust to confounding by library size and outperforms each of the stochastic resampling approaches. We also show that, when overdispersion is low, averaging the (element-wise) squared distance outperforms averaging the unsquared distance, currently implemented in the R package vegan. We illustrate our methods using an analysis of data on inflammatory bowel disease (IBD) in which samples from case participants have systematically smaller library sizes than samples from control participants.Conclusions Our extension of PERMANOVA for presence-absence analyses using a non-stochastic approach that aggregates information over all potential rarefaction replicates without actual resampling is robust to confounding by library size and outperforms stochastic resampling approaches.

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The Stability of Vitamin A from Different Sources in Vitamin Premixes and Vitamin-Trace Mineral Premixes

Applied Sciences ◽

10.3390/app11083657 ◽

2021 ◽

Vol 11 (8) ◽

pp. 3657

Author(s):

Pan Yang ◽

Huakai Wang ◽

Longxian Li ◽

Nan Zhang ◽

Yongxi Ma

Keyword(s):

Vitamin A ◽

Room Temperature ◽

Storage Time ◽

Sampling Point ◽

Finishing Pigs ◽

Trace Mineral ◽

Main Effect ◽

The Stability ◽

Main Effects ◽

Different Sources

This study was conducted to investigate the stability of five commercial vitamin A products in vitamin premixes and vitamin-trace mineral premixes. The five commercial products used were: Xinhecheng, Zhejiang medicine, Kingdomway, DSM, and BASF. The vitamin A products were stored in three vitamin premixes (for suckling, weanling, and finishing pigs) or in vitamin-trace mineral (VTM) premixes (for suckling, weanling, and finishing pigs). Vitamin premixes were stored in an environmentally controlled chamber set at 25 °C and 60% humidity. The VTM premixes were stored at room temperature (approximately 22 °C). Sampling was performed on d 0, 90, 180, 270, and 360. Stability was reported as the residual vitamin A activity (% of initial) at each sampling point. For the stability of vitamin premixes, all interactive and main effects of storage time and vitamin A product were not significant. For the stability of VTM premixes, there was no significant interaction effects between storage time, vitamin A product and main effect of vitamin A product, but the main effect of storage time was significant (p < 0.01). In conclusion, a longer storage time reduced vitamin A activity in VTM premixes but there was no difference in the stability of commercially available vitamin A.

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A rarefaction-without-resampling extension of PERMANOVA for testing presence-absence associations in the microbiome

10.1101/2021.04.06.438671 ◽

2021 ◽

Author(s):

Yijuan Hu ◽

Glen Satten

Keyword(s):

Distance Matrix ◽

Stochastic Approach ◽

Total Sample ◽

R Package ◽

Library Size ◽

Unique Challenge ◽

Unifrac Distance ◽

New Approach ◽

Unweighted Unifrac ◽

Inflammatory Bowel

Background: PERMANOVA is currently the most commonly used method for testing community-level hypotheses about microbiome associations with covariates of interest. PERMANOVA can test for associations that result from changes in which taxa are present or absent by using the Jaccard or unweighted UniFrac distance. However, such presence-absence analyses face a unique challenge: confounding by library size (total sample read count), which occurs when library size is associated with covariates in the analysis. It is known that rarefaction (subsampling to a common library size) controls this bias, but at the potential costs of information loss and the introduction of a stochastic component into the analysis. Methods: Here we develop a non-stochastic approach to PERMANOVA presence-absence analyses that aggregates information over all potential rarefaction replicates without actual resampling, when the Jaccard or unweighted UniFrac distance is used. We compare this new approach to three possible ways of aggregating PERMANOVA over multiple rarefactions obtained from resampling: averaging the distance matrix, averaging the (element-wise) squared distance matrix, and averaging the F-statistic. Results: Our simulations indicate that our non-stochastic approach is robust to confounding by library size and outperforms each of the stochastic resampling approaches. We also show that, when overdispersion is low, averaging the (element-wise) squared distance outperforms averaging the unsquared distance, currently implemented in the R package vegan. We illustrate our methods using an analysis of data on inflammatory bowel disease (IBD) in which samples from case participants have systematically smaller library sizes than samples from control participants.

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Effects of kinship correction on inflation of genetic interaction statistics in commonly used mouse populations

G3 Genes|Genome|Genetics ◽

10.1093/g3journal/jkab131 ◽

2021 ◽

Author(s):

Anna L Tyler ◽

Baha El Kassaby ◽

Georgi Kolishovski ◽

Jake Emerson ◽

Ann E Wells ◽

...

Keyword(s):

Mixed Model ◽

Linear Mixed Model ◽

Genetic Interaction ◽

Recombinant Inbred Lines ◽

Test Statistics ◽

Test Statistic ◽

Kinship Matrix ◽

Main Effect ◽

Main Effects ◽

Interaction Test

Abstract It is well understood that variation in relatedness among individuals, or kinship, can lead to false genetic associations. Multiple methods have been developed to adjust for kinship while maintaining power to detect true associations. However, relatively unstudied, are the effects of kinship on genetic interaction test statistics. Here we performed a survey of kinship effects on studies of six commonly used mouse populations. We measured inflation of main effect test statistics, genetic interaction test statistics, and interaction test statistics reparametrized by the Combined Analysis of Pleiotropy and Epistasis (CAPE). We also performed linear mixed model (LMM) kinship corrections using two types of kinship matrix: an overall kinship matrix calculated from the full set of genotyped markers, and a reduced kinship matrix, which left out markers on the chromosome(s) being tested. We found that test statistic inflation varied across populations and was driven largely by linkage disequilibrium. In contrast, there was no observable inflation in the genetic interaction test statistics. CAPE statistics were inflated at a level in between that of the main effects and the interaction effects. The overall kinship matrix overcorrected the inflation of main effect statistics relative to the reduced kinship matrix. The two types of kinship matrices had similar effects on the interaction statistics and CAPE statistics, although the overall kinship matrix trended toward a more severe correction. In conclusion, we recommend using a LMM kinship correction for both main effects and genetic interactions and further recommend that the kinship matrix be calculated from a reduced set of markers in which the chromosomes being tested are omitted from the calculation. This is particularly important in populations with substantial population structure, such as recombinant inbred lines in which genomic replicates are used.

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Effect of nitrogen fertilizer on growth and yield of semi-dwarf and tall varieties of winter wheat

The Journal of Agricultural Science ◽

10.1017/s0021859600056604 ◽

1978 ◽

Vol 91 (1) ◽

pp. 31-45 ◽

Cited By ~ 39

Author(s):

I. Pearman ◽

S. M. Thomas ◽

G. N. Thorne

Keyword(s):

Winter Wheat ◽

Grain Yield ◽

Leaf Area ◽

Dry Weight ◽

The Other ◽

Growth And Yield ◽

Shoot Dry Weight ◽

Phosphorus And Potassium ◽

Main Effects ◽

Dwarf Variety

SummaryEight amounts of nitrogen ranging from 0 to 210 kg N/ha were applied to two tall and one semi-dwarf variety of winter wheat in the spring of 1975 and 1976. The tall varieties were Cappelle-Desprez and Maris Huntsman; the semi-dwarf variety was Maris Fundin in 1975 and Hobbit in 1976. Interactions between varieties and nitrogen were few and small compared with the main effects. All varieties produced their maximum grain yields with 180 kg N/ha. The yield of the semi-dwarf varieties, but not the others, decreased slightly with more nitrogen.Cappelle-Desprez yielded less grain than the other varieties in both years. In 1975 the yields of Maris Fundin and Maris Huntsman were similar and in 1976 Hobbit yielded more than Maris Huntsman. The varieties had similar numbers of ears at maturity and similar patterns of tillering. The semi-dwarf varieties had most grains per spikelet, and hence grains per ear, and Cappelle-Desprez had least. The semi-dwarf varieties had the smallest grains. The semi-dwarf varieties had less straw than the other varieties and hence the largest ratios of grain to total above-ground dry weight. The decrease in dry weight of stem and leaves between anthesis and maturity was similar for all varieties. In 1975 the efficiency of the top two leaves plus top internode in producing grain was the same for all varieties, but in 1976 Hobbit was more efficient than the other two. There were some small differences between varieties in nutrient uptake that were not related to differences in growth. Maris Fundin tended to have a greater phosphorus and potassium content than the tall varieties. Hobbit contained slightly less nitrogen than the tall varieties at maturity, and had a smaller concentration of nitrogen in the grain.Applying 210 kg N/ha doubled grain yield in 1975. Applying nitrogen resulted in a largeincrease in number of ears and a small increase in number of grains per ear due to the development of more fertile spikelets per ear. Nitrogen decreased dry weight per grain, especially of the semi-dwarf varieties. With extra nitrogen, straw dry weight at maturity, shoot dry weight atanthesis and leaf area were all increased relatively more than grain yield, and stems lost moredry weight between anthesis and maturity than without nitrogen. The year 1976 was exceptionallydry and nitrogen had only small effects in that it affected neither straw dry weight nor numberof ears but slightly increased grain yield by increasing the number of spikelets and number of grains per spikelet. It also increased leaf area proportionately to grain yield. In 1975 nitrogen increased evaporation of water from the crop before anthesis but decreased it after anthesis, even though it continued to increase the extraction of water from below 90 cm.

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246 Examining Melatonin-induced Changes in Uterine Blood Flow and Vaginal Temperatures in Nutrient Restricted Pregnant Heifers

Journal of Animal Science ◽

10.1093/jas/skab235.241 ◽

2021 ◽

Vol 99 (Supplement_3) ◽

pp. 132-132

Author(s):

Zully E Contreras-Correa ◽

Riley D Messman ◽

Hector Sanchez-Rodriguez ◽

Caleb O Lemley

Keyword(s):

Blood Flow ◽

Repeated Measures ◽

Farm Animals ◽

Nutrient Restriction ◽

Dependent Manner ◽

Uterine Blood Flow ◽

Time Interaction ◽

Main Effect ◽

Treatment Interaction ◽

Induced Changes

Abstract The objectives were to examine melatonin mediated changes in temporal uterine blood flow (UBF) and vaginal temperatures (VT) in 54 Brangus heifers (Fall, n = 29; Summer, n = 25) during compromised pregnancy. At d160 of gestation, heifers were assigned to 1 of 4 groups consisting of adequately fed (ADQ-CON; 100% NRC; n=13), global nutrient restricted (RES-CON; 60% NRC; n = 13), and ADQ or RES supplemented with 20 mg of melatonin (ADQ-MEL, n = 13; RES-MEL, n = 15). In the morning (0500h) and afternoon (1300h) of d220 of gestation, temperature dataloggers (Onset Computer Corporation) attached to progesterone-free CIDRs were used to record VT, while UBF was determined via Doppler ultrasonography. Data were analyzed using repeated measures of ANOVA (SAS). Significant differences were found in UBF and VT between Fall and Summer groups (P< 0.05), therefore seasons were individually analyzed. In Fall, a nutrition by treatment interaction was significant, where the RES-CON heifers exhibited reduced total UBF compared to ADQ-CON (5.67±0.68 vs. 7.97±0.54 L/min; P = 0.012). In Summer, there was not a main effect of nutrition (P = 0.390); nevertheless, the MEL heifers exhibited increased total UBF compared to the CON counterparts (8.16±0.73 vs. 6.00±0.70 L/min; P = 0.048). Moreover, there was a nutrition by treatment by time interaction in VT for Fall and Summer heifers (P < 0.0001). In Fall, all groups had decreased VT in the morning compared to the afternoon (P < 0.0001). Whereas, in Summer, VT increased for ADQ-CON, RES-CON, and ADQ-MEL from morning to afternoon (P < 0.0001), while the RES-MEL remained constant throughout the day (P = 0.649). Furthermore, during the afternoon RES-MEL heifers exhibited decreased VT compared to ADQ-CON (38.91±0.09 vs. 39.26±0.09°C, respectively; P=0.039). In summary, nutrient restriction and melatonin supplementation altered UBF in a season dependent manner. Additionally, with the VT differences observed in Summer, future studies should evaluate the potential of melatonin supplementation for mitigating heat stress in farm animals.

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Effect of Frozen Storage on Polyphenol Oxidase, Antioxidant Content, and Color of Pawpaw (Asimina Triloba [L.] Dunal) Fruit Pulp

Journal of Food Research ◽

10.5539/jfr.v6n3p93 ◽

2017 ◽

Vol 6 (3) ◽

pp. 93 ◽

Cited By ~ 3

Author(s):

Robert G Brannan ◽

Gai Wang

Keyword(s):

Ascorbic Acid ◽

Polyphenol Oxidase ◽

Frozen Storage ◽

Color Difference ◽

Browning Index ◽

Air Samples ◽

Significant Difference ◽

Main Effect ◽

Effect Of Treatment ◽

Main Effects

Polyphenol oxidase (PPO) activity values for pawpaw pulp during frozen storage were measured for the main effect of month of storage at three levels (0, 4, 8 months) and treatment at four levels (vacuum, air, ascorbic acid or n-acetylcysteine). A significant effect of treatment was observed in PPO activity (p<0.001). Post hoc analysis revealed no significant difference between samples that were vacuum packaged and those for which no attempt to exclude air was made. The addition of the two chemical browning inhibitors significantly lowered PPO activity. Ascorbic acid exhibited a significant 69% reduction in PPO activity compared to vacuum and air samples and n-acetylcysteine was significantly more effective than ascorbic acid and almost completely inhibited PPO activity compared to the vacuum and air samples. CIELAB tristimulous color values (L*, a*, b*) were used to generate the applied color values total color difference (DE), browning index, hue and chroma in pawpaw pulp for the two main effects. Analysis of variance for the main effects showed significance for all seven color attributes at p<0.001. For the main effect of storage time, ANOVA showed significance during storage for all seven color attributes at p<0.001, indicating that there were color changes during storage. Pawpaw pulp samples at 8 months of storage were significantly darker (lower L*), more yellow (higher b*), more vivid (higher chroma), and had a higher browning index than the samples at 0 or 4 months of storage. For the main effect of treatment, ascorbic acid and n-acetylcysteine treatment produced pawpaw pulp that was significantly different than samples to which air was not excluded for all seven dependent color variables. Specifically, n-acetylcysteine and ascorbic acid produced pulp that was lighter (higher L*), less red (lower a*), and more yellow (higher b* and hue), more vivid (higher chroma), and exhibited more color difference (higher DE). A strategy to inhibit enzymatic browning during frozen storage would be useful for the nascent pawpaw industry.

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The Ergonomic Impact of Swype

Proceedings of the Human Factors and Ergonomics Society Annual Meeting ◽

10.1177/1541931213601317 ◽

2016 ◽

Vol 60 (1) ◽

pp. 1374-1378 ◽

Cited By ~ 2

Author(s):

Ibukun A. Sonaike ◽

Tosin A. Bewaji ◽

Paul Ritchey ◽

S. Camille Peres

Keyword(s):

New Technology ◽

Touch Screen ◽

Dynamic Activity ◽

Extensor Muscles ◽

Main Effect ◽

Potential Risks ◽

Touch Screen Devices ◽

Study Participants ◽

Main Effects ◽

Biomechanical Strain

Background:Shape writing is relatively new technology for on-screen keyboards that enable users of mobile touch-screen devices to input text by drawing continuous lines. With growth of touch-screen device usage, there has risen the need to investigate potential risks that may occur during prolonged usage. Objective: The biomechanical strain on upper limb muscles were assessed while study-participants used Swype technology on a tablet touch screen device and compared with traditional/regular input methods. Methods: Study-participants performed typing tasks (email and text) using Swype and regular input methods under counterbalanced conditions with sEMG data collected to measure muscle activity during tasks. Results: Email & Text had the same exertion for all muscles except the Extensor. The interaction between task and muscle was significant, F (1.6, 27.5) = 15.39, p < .001, ηp2 = 0.48. The interaction between muscle, task and method was also significant, F (2.19, 37.19) = 3.6, p = 0.03, ηp2= 0.18. Exertion was lower for Swype but with marginal significance. Overall, Email resulted in less dynamic activity than Text with Main effects F(1, 17) = 10.07, p = 0.006, ηp2 = 0.37. Extensor has more dynamic activity than other muscles with main effect F(1.8, 29.9) = 16.51, p < 0.001, ηp2 = 0.49. Conclusion: Results indicate that Swype presents no more biomechanical strain than regular input for most muscles. Swype may result in less exertion for the Extensor muscles in the lower arm. This may be particularly true for tasks requiring interactions like those found in the email task.

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