Variability, Stability, and Flexibility in the Speech Kinematics and Acoustics of Adults Who Do and Do Not Stutter

It is well known that people who do and do not stutter produce speech differently, at least some of the time, even when perceived as fluent. One way that investigators have assessed these differences is by measuring variability, or the inconsistency of repeated speech movements. Variability in speech has typically been quantified using linear analysis techniques (e.g., measures of central tendency), and results have indicated that people who stutter produce speech that is (sometimes) characterized by increased variability. However, variability is a complex phenomenon, one that cannot be assessed by linear methods alone. This dissertation employs linear and nonlinear analysis techniques to examine the nature of variability, stability, and flexibility in stuttering and non-stuttering speakers. Two experiments are reported in this dissertation. The first is a pilot study in which 11 participants judged short utterances that were manipulated in gap (or pause) duration to be fluent or disfluent. This preliminary study facilitated the selection of \u27fluent\u27 utterances for the primary experiment, which measured lip aperture kinematics and acoustics for 20 speakers who stutter and 21 speakers who do not stutter, under two manipulations: 1) audience and non-audience; 2) increasing linguistic complexity. Results from the primary experiment corroborated results from prior studies that used linear techniques to show that 1) adults who stutter exhibit more effector variability than adults who do not stutter when target utterances are embedded in sentences of increased linguistic complexity, and 2) linear acoustic measures are as effective as linear kinematic measures for quantifying variability. Nonlinear analysis techniques demonstrated that adults who stutter exhibit more deterministic structure in lip aperture dynamics. Furthermore, cognitive-emotional stress (i.e., the presence of an audience) resulted in decreased surface variability, increased deterministic structure, decreased stationarity, and decreased signal complexity in speakers who stutter, but not in those who do not stutter. Thus, adults who stutter appear to exhibit less overall stability, which leads to a more rigid, less flexible approach to speech production, especially when cognitive-emotional stressors are placed on their speech motor systems. These findings highlight the benefits of using nonlinear analysis techniques to examine variability in speech production. Specifically, the results demonstrated that speech movements that appear to be less variable on the surface, may in fact be overly deterministic and nonstationary\u27two attributes that indicate system instability in complex biological systems. Thus, a combination of linear and nonlinear approaches is warranted in future investigations of speech production

My Client Knows That He’s About to Stutter: How Can We Address Stuttering Anticipation during Therapy with Young People Who Stutter?

Stuttering anticipation is endorsed by many people who stutter as a core aspect of the stuttering experience. Anticipation is primarily a covert phenomenon and people who stutter respond to anticipation in a variety of ways. At the same time as anticipation occurs and develops internally, for many individuals the “knowing” or “feeling” that they are about to stutter is a primary contributor to the chronicity of the disorder. In this article, we offer a roadmap for both understanding the phenomenon of anticipation and its relevance to stuttering development. We introduce the Stuttering Anticipation Scale (SAS)—a 25-item clinical tool that can be used to explore a client’s internal experience of anticipation to drive goal development and clinical decision making.We ground this discussion in a hypothetical case study of “Ryan,” a 14-yearold who stutters, to demonstrate how clinicians might use the SAS to address anticipation in therapy with young people who stutter

Applying Accelerator Mass Spectrometry for Low-Level Detection of Complex Engineered Nanoparticles in Biological Media

Complex engineered nanoparticles (CENPs), which have different core and surface components, are being developed for medicinal, pharmaceutical and industrial applications. One of the key challenges for environmental health and safety assessments of CENPs is to identify and quantity their transformations in biological environments. This study reports the effects of in vivo exposure of citrate-coated nanoalumina with different rare isotope labels on each component. This CENP was dosed to the rat and accelerator mass spectrometry (AMS) was used to quantify 26Al, 14C, and their ratio in the dosing material and tissue samples. For CENPs detected in the liver, the rare isotope ratio, 14C/26Al, was 87% of the dosing material\u27s ratio. The citrate coating on the nanoalumina in the liver was stable or, if it degraded, its metabolites were incorporated with nearby tissues. However, in brain and bone where little alumina was detected, the rare isotope ratio greatly exceeded that of the dosing material. Therefore, in the animal, citrate dissociated from CENPs and redistributed to brain and bone. Tracking both the core and surface components by AMS presents a new approach for characterizing transformations of CENPs components in biological milieu or environments

Imaging calcium microdomains within entire astrocyte territories and endfeet with GCaMPs expressed using adeno-associated viruses.

Intracellular Ca(2+) transients are considered a primary signal by which astrocytes interact with neurons and blood vessels. With existing commonly used methods, Ca(2+) has been studied only within astrocyte somata and thick branches, leaving the distal fine branchlets and endfeet that are most proximate to neuronal synapses and blood vessels largely unexplored. Here, using cytosolic and membrane-tethered forms of genetically encoded Ca(2+) indicators (GECIs; cyto-GCaMP3 and Lck-GCaMP3), we report well-characterized approaches that overcome these limitations. We used in vivo microinjections of adeno-associated viruses to express GECIs in astrocytes and studied Ca(2+) signals in acute hippocampal slices in vitro from adult mice (aged ∼P80) two weeks after infection. Our data reveal a sparkling panorama of unexpectedly numerous, frequent, equivalently scaled, and highly localized Ca(2+) microdomains within entire astrocyte territories in situ within acute hippocampal slices, consistent with the distribution of perisynaptic branchlets described using electron microscopy. Signals from endfeet were revealed with particular clarity. The tools and experimental approaches we describe in detail allow for the systematic study of Ca(2+) signals within entire astrocytes, including within fine perisynaptic branchlets and vessel-associated endfeet, permitting rigorous evaluation of how astrocytes contribute to brain function

The Controversies and Difficulties of Diagnosing Primary Ciliary Dyskinesia

We welcome the correspondence from Lavie and Amirav (1), highlighting the difficulties diagnosing primary ciliary dyskinesia (PCD) and the role of high-speed video analysis (HSVA). As members of the European Respiratory Society (ERS) PCD Diagnostic Task Force (2) and/or large PCD Centres, we agree that HSVA has an important role that is not recognized by the American Thoracic Society (ATS) PCD Diagnostic Guideline (3). This risks a large proportion of false-negative “missed” diagnoses and a sizable number of false-positive cases; we make additional important observations.</div

Statin use and risk of community acquired pneumonia in older people: population based case-control study

Objective To test the hypothesis that hydroxymethyl glutaryl coenzyme A reductase inhibitors (statins) may decrease the risk of community acquired pneumonia

Activation in Right Dorsolateral Prefrontal Cortex Underlies Stuttering Anticipation

People who stutter learn to anticipate many of their overt stuttering events. Despite the critical role of anticipation, particularly how responses to anticipation shape stuttering behaviors, the neural bases associated with anticipation are unknown. We used a novel approach to identify anticipated and unanticipated words in 22 adult stutterers, which were produced in a delayed-response task while hemodynamic activity was measured using functional near infrared spectroscopy (fNIRS). Twenty-two control participants were included such that each individualized set of anticipated/unanticipated words was produced by one stutterer and one control. We conducted an analysis on the right dorsolateral prefrontal cortex (R-DLPFC) based on converging lines of evidence from the stuttering and cognitive control literatures. We also assessed connectivity between the R-DLPFC and right supramarginal gyrus (R-SMG), two key nodes of the frontoparietal network (FPN), to assess the role of cognitive control, particularly error-likelihood monitoring, in stuttering anticipation. All analyses focused on the five-second anticipation phase preceding the go signal to produce speech. Results indicate that anticipated words are associated with elevated activation in the R-DLPFC, and that compared to non-stutterers, stutterers exhibit greater activity in the R-DLPFC, irrespective of anticipation. Further, anticipated words are associated with reduced connectivity between the R-DLPFC and R-SMG. These findings highlight the potential roles of the R-DLPFC and the greater FPN as a neural substrate of stuttering anticipation. The results also support previous accounts of error-likelihood monitoring and action-stopping in stuttering anticipation. Overall, this work offers numerous directions for future research with clinical implications for targeted neuromodulation

Ohm's Law for a Relativistic Pair Plasma

We derive the fully relativistic Ohm's law for an electron-positron plasma. The absence of non-resistive terms in Ohm's law and the natural substitution of the 4-velocity for the velocity flux in the relativistic bulk plasma equations do not require the field gradient length scale to be much larger than the lepton inertial lengths, or the existence of a frame in which the distribution functions are isotropic.Comment: 12 pages, plain TeX, Phys. Rev. Lett. 71 3481 (1993

A Physical Classification Scheme for Blazars

Blazars are currently separated into BL Lacertae objects (BL Lacs) and flat spectrum radio quasars (FSRQ) based on the strength of their emission lines. This is done rather arbitrarily by defining a diagonal line in the Ca H&K break value -- equivalent width plane, following Marcha et al. We readdress this problem and put the classification scheme for blazars on firm physical grounds. We study ~100 blazars and radio galaxies from the Deep X-ray Radio Blazar Survey (DXRBS) and 2 Jy radio survey and find a significant bimodality for the narrow emission line [OIII] 5007. This suggests the presence of two physically distinct classes of radio-loud AGN. We show that all radio-loud AGN, blazars and radio galaxies, can be effectively separated into weak- and strong-lined sources using the [OIII] 5007 -- [OII] 3727 equivalent width plane. This plane allows one to disentangle orientation effects from intrinsic variations in radio-loud AGN. Based on DXRBS, the strongly beamed sources of the new class of weak-lined radio-loud AGN are made up of BL Lacs at the ~75 per cent level, whereas those of the strong-lined radio-loud AGN include mostly (~97 per cent) quasars.Comment: 19 pages, 10 figures. Accepted for publication in MNRA