It is of great importance to be able to unambiguously interpret deoxyribonucleic acid (DNA) profiles, especially with Low Template (LT) DNA and mixture DNA that may contain major and minor contributors. Reducing stochastic effects, such as heterozygote peak imbalance, dropouts, and stutter artifacts have been studied by scientists in order to improve the evaluation of low quality DNA profile. There has been much research on a compatible solute, trehalose, in its effectiveness in enhancing the polymerase chain reaction (PCR), especially with GC-rich templates of DNA, and thermal stabilizing Thermus Aquaticus (Taq) DNA polymerases. Based on previous research, the effect of trehalose on peak heights, peak height ratios, and stutter ratios (n-1) from 15 short tandem repeats (STR) loci of the AmpFℓSTR® Identifiler® Plus PCR Amplification Kit was evaluated with 0.025ng, 0.05ng, 0.1ng, and 1ng of DNA, through the addition of 0M (control), 0.2M, and 0.4M of trehalose for each quantity of DNA. Although there was an observation regarding changes in average peak heights at 1ng of DNA with the addition of 0.2M, and 0.4M of trehalose, no conclusions could be made with the average peak heights for 0.025ng, 0.05ng, 0.1ng, and 1ng of DNA. The reason is that the propagation of pipetting error during the preparation of each batch could have contributed to the difference in the amount of DNA between each conditions which can be directly reflected in peak heights. Furthermore, unexpected discrepancy between the average peak heights for 0.1ng of DNA from the first and the second experiments rendered 0.1ng of DNA incompatible for comparison. With regards to average peak height ratios for 0.025ng, 0.05ng, 0.1ng, and 1ng of DNA, and average reverse stutter ratios for 0.1ng, and 1ng of DNA, there were no evidence to suggest that 0.2M or 0.4M of trehalose had any effects. Consistent trends for 0.1ng (Exp. 1 and 2) and 1ng of DNA from a statistical analysis through one-way ANOVA of individual loci, suggested that trehalose may have varying effects on certain loci. However, this observation must be approached with caution as it is uncertain whether unique trends across each data sets for certain loci were observed by chance due to small sample sizes or due to mechanisms of stutters and trehalose that are currently unknown. Future studies regarding the effect of trehalose on peak heights should be done with more precision through minimizing pipetting error, which can be accomplished by preparing one batch from which aliquots are taken. The result of the research does not show enough evidence to prove the usefulness of trehalose since the addition of trehalose does not yield consistently higher average peak heights and peak height ratios, and lower average reverse stutter ratios across 15 STR loci. Therefore, our results do not support that 0.2M and 0.4M of trehalose are useful within the parameter of forensic DNA analysis as they do not enhance the polymerase chain reaction (PCR) and improve stochastic effects for DNA profiles.

Forensic genotyping uses a multiplex short tandem repeat (STR) assay to amplify deoxyribonucleic acid (DNA) samples. One of the artifacts mostly commonly encountered in forensic DNA analysis is stutter, which are non-specific products from the polymerase chain reaction (PCR) that are typically one repeat unit shorter in length than the allelic amplicon. While stutter peaks are typically no taller than 10% of the parent peak on electropherograms, their peak heights can fall into similar ranges as minor contributor alleles in mixtures, creating a problem of how to distinguish artifacts from true allele peaks in these situations. One way to potentially address this issue is to find a PCR method that produces a much lower amount of stutter than the method currently used, which involves amplifying samples with commercial PCR kits designed for forensic applications. These kits all use some form of Taq DNA polymerase (derived from Thermus aquaticus). In an effort to examine whether the type of enzyme used in an assay affects the resulting stutter rates observed, the existing GlobalFiler™ PCR Amplification Kit (Applied Biosystems) protocol for forensic multiplex STR assays was modified to test different types of enzymes. This was done by amplifying the same DNA sample with GlobalFiler primers and different commercial proofreading enzymes and their accompanying reaction buffer using manufacturer-recommended PCR parameters. The DNA sample originated from a buccal swab that was extracted on the EZ1® Advanced (Qiagen). The DNA solution was quantified using the Quantifiler™ Duo DNA Quantification Kit (Applied Biosystems) on the 7500 Real-Time PCR System (Applied Biosystems). In order to first establish the validity of switching out enzymes in an established protocol, a DNA sample was amplified with the Type-it® Microsatellite Kit (Qiagen), another Taq-based kit that is also marketed for use in multiplex STR assays. After a complete profile was successfully generated, research proceeded with testing various high-fidelity DNA polymerases. Some of the enzymes tested were known to be Pyrococcus-like while others were fused to a DNA-binding domain to enhance processivity. Taq polymerases tend to produce products with 3’adenine-overhangs while proofreading enzymes produce blunt-ends. This change caused a one base pair difference in the resulting amplicon lengths, which was accommodated by manually assigning genotypes after results from fragment analysis by capillary electrophoresis using a 3130 Genetic Analyzer (Applied Biosystems) were interpreted by the GeneMapper™ software (Applied Biosystems). Additional amplification kits tested were: the UCP HiFidelity PCR Kit (Qiagen), Phusion™ Hot Start II High-Fidelity DNA Polymerase (Thermo Scientific), Platinum™ SuperFi™ II DNA Polymerase (Invitrogen), iProof™ High-Fidelity DNA Polymerase (Bio-Rad), Q5® High-Fidelity DNA Polymerase (New England Biolabs), and TruFi™ DNA Polymerase (Azura Genomics). Most of the kits produced profiles exhibiting a high degree of uneven amplification and varying levels of allelic dropout. In addition, all of the kits tested had much shorter peak heights compared to using GlobalFiler. Changing the type of enzyme used in an established protocol was found to be less straightforward than anticipated. Due to the poor quality results obtained in the first pass of trials, a few kits were selected to undergo optimization in the hopes of achieving higher quality results from which further analyses, such as comparing stutter rates, could be more reliably conducted. Both altered reagent amounts (higher enzyme concentration, higher DNA input mass) and different PCR parameters (decreased denaturation temperature, varying annealing temperature, decreased extension temperature, longer extension cycles, and longer final extension stage) were assessed. Only an increase in extension cycling time was found to produce better peak heights while maintaining balanced amplification of most of the targeted loci. Initial samples amplified with the Phusion enzyme exhibited multiple non-specific artifacts that were not stutter. Raising the annealing temperature for that enzyme’s protocol eliminated this issue. Therefore, higher annealing temperatures were pre-emptively used for several of the other enzymes tested. One of the explanations proposed for the uneven amplification observed is the presence of inhibitors in the commercial buffers used affecting downstream capillary electrophoresis. The Q5 High-Fidelity and TruFi DNA polymerases produced the best quality profiles; the UCP HiFidelity PCR Kit had the poorest results. Preliminary results indicated that none of the protocol alterations implemented significantly decreased stutter rates, nor was any one commercial enzyme found to have consistently lower stutter rates than the GlobalFiler kit. Due to the low number of trials carried out, the findings from this study require more replications with a wider variety of DNA polymerases to confirm that the type of enzyme used in an assay does not affect stutter rates.

Using computer systems for probabilistic genotyping on DNA evidence in forensic casework is beneficial as it allows a complete analysis of the data available for a wide range of profiles, a range that is limited when analyzed manually. One such software, Bulletproof, uses the exact method as the statistical foundation of its web-based interface to estimate the likelihood ratio of two hypotheses that explain the given evidence. In this investigation, the capability of Bulletproof was examined by analyzing the effects of evidence and reference sample template amount, injection time, and stutter filter utilization on likelihood ratio. In terms of likelihood ratio, deconvolution by the software is more efficient in cases in which evidence samples of high contrast ratios (such as 1:9 vs. 1:1) and low contributor count have high template, and when sample injection times are low. Reference sample template amount and injection time are less impactful than that of evidentiary samples. As with unknown samples, reference samples should be analyzed beforehand and artifacts removed for better deconvolution.

This study investigates the extent to which the fluent life partners (LPs) of persons who stutter (PWS) understand the effect stuttering has on their partner who stutters' communication attitude. This was accomplished by administering the Communication Attitude Test for Adults Who Stutter (BigCAT; Vanryckeghem & Brutten, 2018), a subtest of the Behavior Assessment Battery (BAB; Vanryckeghem & Brutten, 2018). The BigCAT was administered to 33 PWS and a modified version was administered to their LPs via Qualtrics, an online survey software system. Between-group total score comparison revealed no significant difference in total scores, and a low-medium score correlation was evidenced. Within both groups, participants age and gender did not have a significant effect on total scores. The perception of stuttering severity was found to significantly influence BigCAT scores within each group. No differential effect of duration of relationship on score agreement was found to exist. A high Cronbach Alpha coefficient was obtained for both test forms. Between-group item score comparison revealed that only answers on two out of the 34 items differed significantly. They were related to frequency of speech disruption and avoidance of persons, places or situations. Item 24 had a perfect correlation between the two groups and relates to common behaviors PWS exhibit in trying to attain more fluency. Overall, the findings of this study show that LPs of PWS have a general understanding of the impact stuttering has on their partner who stutters' communication attitude.

No description available.

Research examining bilinguals who stutter (BWS) is limited; in particular there are few studies that have considered examining features of speech motor control in BWS. The present study was designed to examine features of speech motor control in bilingual speakers of Mandarin and English. Speech motor control was examined through the acoustic analysis of speaking rate, voice onset time (VOT) and stuttering adaptation. Participants ranged from age between 9 and 27 years. Upon completion of a language dominance questionnaire, two BWS participants were found to be English dominant and three were Mandarin dominant. Each BWS participant was matched to age/sex matched control participants (BWNS). Results for the BWS participants found more stuttering in the less dominant language based on a measure of percentage of syllables stuttered. All of the BWS participants demonstrated stuttering adaptation and there was no significant difference in the amount of adaptation for Mandarin and English. There was no difference found between BWS and BWNS for speaking rate and VOT. In spite of the similarity between BWS and BWNS, speaking rate in Mandarin appeared to be faster compared to English. These findings suggest that speech motor control in BWS and BWNS are similar and current application of these findings to the clinical setting is discussed.

Abstract Objective: The aim of the present study was to investigate mechanisms of real-time language production of adults who stutter. Method: Data were analyzed for 19 typically fluent young adults (TFA) and 19 young adults who stutter (AWS). Participants performed a masked picture priming task where priming stimuli consisted of two conditions 1) Identity- a masked printed prime word identical to the picture target label, and 2) Unrelated- a masked printed prime word unrelated to the picture target label. Brain event-related potentials (ERPs), time-locked to pictures eliciting spontaneous naming, were recorded, as well as naming accuracy and reaction times. Results: Masked priming effects on ERP components were compared between groups. Priming modulated N400 amplitude in TFA while, at the same latency, priming modulated P300 amplitude in AWS. N400 is attributed to processing of meaningful stimuli, and P300 is a measure of effortful control. An even later priming effect generalized to both groups. Conclusion: Results suggest that post-lexical processing was similar in AWS and TFA, while lexical-semantic processing operated differently. Whereas TFA evidenced automaticity in activation and selection of target picture labels, AWS evidenced enhanced attentional control during lexical selection. We propose that AWS recruited a compensatory attentional mechanism to stabilize activation of target words on the path to naming. These conclusions suggest that clinically, AWS may benefit from vocabulary enrichment and attentional control treatment.

No description available.

The thesis deals with stuttering in adulthood. The first part provides a theoretical basis for using professional literature. It contains theme of communication, communication disorders, stuttering (terminology, incidence, etiology and symptomatology, classification, diagnosis and therapy of selected techniques for adult age), and the International Stuttering Awareness Day. Another theme of the work is the employment of people with stuttering. Thesis also includes advice on how to talk to stutterers and guide phoning for stutterers. The practical part contains its own investigation, processing and results. KEY WORDS Communication, Stuttering, Poeple who stutter, Stuttering in adult age, International Stuttering Awareness Day, Stutterer and career choice

Om ’n beroepskeuse te maak of oor ’n (nuwe) beroep te besluit, is op sigself ’n oefening wat geweldige emosionele insig, krag en volwassenheid verg. Indien hierdie belangrike besluit geneem moet word deur ’n adolessent wat boonop hakkel, verg dit soveel me er innerlike sterkte. Vir so ’n jongmens is dit ’n enorme taak om ’n beeld van hom-/haarself in die toekoms te projekteer en besluite rakende ’n beroep en/of loopbaan te neem. Om te hakkel beïnvloed ongetwyfeld ’n adolessent se toekomsvisie en - planne. Benewens die feit dat die siening van die self in die hede aangepas moet word om ruimte te laat vir hakkel as ’n persoonlikheidseienskap en besluite wat dit behels en beïnvloed, moet die betrokke adolessent ook hierdie beeld op so ʼn wyse kan aanpas dat die self suksesvol in die toekoms geprojekteer kan word. Dit is die primêre doelwit van die onderhawige studie om vas te stel watter waarde lewensontwerpberading inhou vir ’n adolessent wat hakkel, en die studie word onderneem teen die agtergrond van beide die sisteemteorie en die sosiale konstruktivisme ten einde die navorser te help om op die ervaring van die deelnemer binne sy unieke konteks te fokus. Die studie is spesifiek gerig op die belewingswêreld van die adolessent wat hakkel. Ten einde die subjektiewe en diverse ervarings van die deelnemer beter te begryp, het ek ondersoek gedoen na die wyse waarop adolessente oor die algemeen (en my deelnemer in die besonder) deur middel van interaksie met ander (en die omgewing) deur die lens van die sosiale konstruktivisme vir hulself betekenis skep. Ek het vanuit ʼn kwalitatiewe paradigma gewerk en ʼn gevalstudie gedoen waar die eenheid van ondersoek ʼn adolessent was wat hakkel. My studie het gefokus op aanpasbaarheid as ’n element van hierdie adolessent se lewensontwerp, maar dan spesifiek ook op die wyse waarop die vier kerndimensies van aanpasbaarheid in sy lewe voltrek, te wete beroepsbelang, beroepsbeheer, beroepsnuuskierigheid en beroepselfvertroue. Ek het oorkoepelend ondersoek ingestel na die waarde van lewensontwerpberading in terme van die betekenisgewing (meaning making) en ‘heelwording’ (becoming more whole) van hierdie deelnemer as ’n persoon wat hakkel. ENGLISH : Making a career choice or deciding about a (new) career/job is an exercise that in itself already requires significant emotional insight, command and maturity. When this important decision is to be made by an adolescent who also stutters, this requires so much more inner strength. For such a youth it is a gigantic task to project an image of him/herself into the future and to make decisions concerning a future job/career. To stutter, unquestionably influences a person’s future vision and plans. Not only does it require an adaptation of the view of the self in the present to make space for this personality trait and the decisions that will influence and concern it, but the adolescent who stutters also will have to adjust this image of the self in order to successfully project the self into the future. It is the primary goal of this study to investigate the value of life design counselling for an adolescent who stutters and it is done against the background of both the systems theory and social constructivism in order to help the researcher to focus on the experience of the participant within his unique context. The study is specifically the world of experience of the adolescent who stutters. In order to better understand the subjective and diverse experiences of the participant, I investigated through the lens of social constructivism the way in which adolescents in general (and my participant in particular) created meaning through interaction with others (and the environment). I worked from a qualitative paradigm and conducted a case study where the unit of investigation was an adolescent who stutters. My study focused on adaptability as an element of this adolescent’s life design, but then specifically on the way that the four core dimensions of adaptability, that is career concern, career control, career curiosity and career confidence, manifest themselves in his life. I conducted an overall investigation into the value that life design counselling holds for the participant as a person who stutters in terms of his making meaning of life and becoming more whole as a person. / Dissertation (MEd)--University of Pretoria, 2010. / Educational Psychology / unrestricted