2,153 research outputs found
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
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Field responsive mechanical metamaterials.
Typically, mechanical metamaterial properties are programmed and set when the architecture is designed and constructed, and do not change in response to shifting environmental conditions or application requirements. We present a new class of architected materials called field responsive mechanical metamaterials (FRMMs) that exhibit dynamic control and on-the-fly tunability enabled by careful design and selection of both material composition and architecture. To demonstrate the FRMM concept, we print complex structures composed of polymeric tubes infilled with magnetorheological fluid suspensions. Modulating remotely applied magnetic fields results in rapid, reversible, and sizable changes of the effective stiffness of our metamaterial motifs
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
Cy 2201-3201: An Edge-on Spiral Gravitational Lens
We present the CXOCY J220132.8-320144 system, which is composed of an edge-on
spiral galaxy at z=0.32 lensing a z=3.9 background quasar. Two images of the
quasar are seen. The geometry of the system is favorable to separate the
relative mass contribution of the disk and halo in the inner parts of the
galaxy. We model the system with one elliptical mass component with the same
ellipticity as the light distribution and manage to reproduce the quasar image
positions and fluxes. We also model the system with two mass components, disk
and halo. Again, we manage to reproduce the quasar image positions and fluxes.
However, all models predict at least a third visible image close to the disk
that is not seen in our images. We speculate that this is most likely due to
extinction by the disk. We also measure the rotational velocity of the galaxy
at 2.7 disk scale radius to be v_c=130 +/- 20 km/s from the [OII] emission
lines. When adding the rotational velocity constraint to the models, we find
that the contribution to the rotational velocity of the disk is likely to be
equal to or larger than the contribution of the halo at this radius. The
detection of the third image and a more accurate measurement of the rotational
velocity would help to set tighter constraints on the mass distribution of this
edge-on spiral galaxy.Comment: 8 pages, 5 figures, ApJ accepted (scheduled Dec 1 2006, 652, 955
Experimental intravascular hemolysis induces hemodynamic and pathological pulmonary hypertension: association with accelerated purine metabolism
Pulmonary hypertension (PH) is emerging as a serious complication associated with hemolytic disorders, and plexiform lesions (PXL) have been reported in patients with sickle cell disease (SCD). We hypothesized that repetitive hemolysis per se induces PH and angioproliferative vasculopathy and evaluated a new mechanism for hemolysis-associated PH (HA-PH) that involves the release of adenosine deaminase (ADA) and purine nucleoside phosphorylase (PNP) from erythrocytes. In healthy rats, repetitive admin- istration of hemolyzed autologous blood (HAB) for 10 days produced reversible pulmonary parenchymal injury and vascular remodeling and PH. Moreover, the combination of a single dose of Sugen-5416 (SU, 200mg/kg) and 10-day HAB treatment resulted in severe and progressive obliterative PH and formation of PXL (Day 26, right ventricular peak systolic pressure (mmHg): 26.1 1.1, 41.5 0.5 and 85.1 5.9 in untreated, HAB treated and SUĂľHAB treated rats, respectively). In rats, repeti- tive administration of HAB increased plasma ADA activity and reduced urinary adenosine levels. Similarly, SCD patients had higher plasma ADA and PNP activity and accelerated adenosine, inosine, and guanosine metabolism than healthy controls. Our study provides evidence that hemolysis per se leads to the development of angioproliferative PH. We also report the development of a rat model of HA-PH that closely mimics pulmonary vasculopathy seen in patients with HA-PH. Finally, this study suggests that in hemolytic diseases released ADA and PNP may increase the risk of PH, likely by abolishing the vasoprotective effects of adenosine, inosine and guanosine. Further characterization of this new rat model of hemolysis-induced angioproliferative PH and additional studies of the role of purines metabolism in HA-PH are warranted
Phosphorylated tau/amyloid beta 1-42 ratio in ventricular cerebrospinal fluid reflects outcome in idiopathic normal pressure hydrocephalus
<p>Abstract</p> <p>Background</p> <p>Idiopathic normal pressure hydrocephalus (iNPH) is a potentially reversible cause of dementia and gait disturbance that is typically treated by operative placement of a ventriculoperitoneal shunt. The outcome from shunting is variable, and some evidence suggests that the presence of comorbid Alzheimer's disease (AD) may impact shunt outcome. Evidence also suggests that AD biomarkers in cerebrospinal fluid (CSF) may predict the presence of AD. The aim of this study was to investigate the relationship between the phosphorylated tau/amyloid beta 1-42 (ptau/Aβ1-42) ratio in ventricular CSF and shunt outcome in patients with iNPH.</p> <p>Methods</p> <p>We conducted a prospective trial with a cohort of 39 patients with suspected iNPH. Patients were clinically and psychometrically assessed prior to and approximately 4 months after ventriculoperitoneal shunting. Lumbar and ventricular CSF obtained intraoperatively, and tissue from intraoperative cortical biopsies were analyzed for AD biomarkers. Outcome measures included performance on clinical symptom scales, supplementary gait measures, and standard psychometric tests. We investigated relationships between the ptau/Aβ1-42 ratio in ventricular CSF and cortical AD pathology, initial clinical features, shunt outcome, and lumbar CSF ptau/Aβ1-42 ratios in the patients in our cohort.</p> <p>Results</p> <p>We found that high ptau/Aβ1-42 ratios in ventricular CSF correlated with the presence of cortical AD pathology. At baseline, iNPH patients with ratio values most suggestive of AD presented with better gait performance but poorer cognitive performance. Patients with high ptau/Aβ1-42 ratios also showed a less robust response to shunting on both gait and cognitive measures. Finally, in a subset of 18 patients who also underwent lumbar puncture, ventricular CSF ratios were significantly correlated with lumbar CSF ratios.</p> <p>Conclusions</p> <p>Levels of AD biomarkers in CSF correlate with the presence of cortical AD pathology and predict aspects of clinical presentation in iNPH. Moreover, preliminary evidence suggests that CSF biomarkers of AD may prove useful for stratifying shunt prognosis in patients being evaluated and treated for this condition.</p
Measuring black-hole parameters and testing general relativity using gravitational-wave data from space-based interferometers
Among the expected sources of gravitational waves for the Laser
Interferometer Space Antenna (LISA) is the capture of solar-mass compact stars
by massive black holes residing in galactic centers. We construct a simple
model for such a capture, in which the compact star moves freely on a circular
orbit in the equatorial plane of the massive black hole. We consider the
gravitational waves emitted during the late stages of orbital evolution,
shortly before the orbiting mass reaches the innermost stable circular orbit.
We construct a simple model for the gravitational-wave signal, in which the
phasing of the waves plays the dominant role. The signal's behavior depends on
a number of parameters, including , the mass of the orbiting star, ,
the mass of the central black hole, and , the black hole's angular momentum.
We calculate, using our simplified model, and in the limit of large
signal-to-noise ratio, the accuracy with which these quantities can be
estimated during a gravitational-wave measurement. Our simplified model also
suggests a method for experimentally testing the strong-field predictions of
general relativity.Comment: ReVTeX, 16 pages, 5 postscript figure
Spectral method for the time-dependent Gross-Pitaevskii equation with a harmonic trap
We study the numerical resolution of the time-dependent Gross-Pitaevskii
equation, a non-linear Schroedinger equation used to simulate the dynamics of
Bose-Einstein condensates. Considering condensates trapped in harmonic
potentials, we present an efficient algorithm by making use of a spectral
Galerkin method, using a basis set of harmonic oscillator functions, and the
Gauss-Hermite quadrature. We apply this algorithm to the simulation of
condensate breathing and scissors modes.Comment: 23 pages, 5 figure
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