52,139 research outputs found
Multi-modal discrimination learning in humans: evidence for configural theory
No full textHuman contingency learning was used to compare the predictions of configural and elemental theories. In three experiments, participants were required to learn which indicators were associated with an increase in core temperature of a fictitious nuclear plant. Experiments 1 and 2 investigated the rate at which a triple-element stimulus (ABC) could be discriminated from either single-element stimuli (A, B, and C) or double-element stimuli (AB, BC, and AC). Experiment 1 used visual stimuli, whilst Experiment 2 used visual, auditory, and tactile stimuli. In both experiments the participants took longer to discriminate the triple-element stimulus from the more similar double-element stimuli than from the less similar single-element stimuli. Experiment 3 tested for summation with stimuli from either single or multiple modalities and summation was found only in the latter. Thus the pattern of results seen in Experiments 1 and 2 was not dependent on whether the stimuli were single- or multi-modal nor was it dependent on whether the stimuli could elicit summation. This pattern of results is consistent with the predictions of Pearce’s (1987) configural theory
Evidence for a shift from true place navigation to directional responding in one variant of the morris water task.
No full textPrevious work from our laboratory has demonstrated that rats display a preference for directional responding over place navigation in a wide range of procedural variants of the Morris water task. A preference for place navigation has only been observed when the pool is reduced as a cue by filling it with water. Studies using dry-land mazes suggest that rats place navigate early in training and later switch to other forms of responding (e.g., motor). The present study evaluated whether rats switch from place navigation to directional responding in the “full pool” variant of the water task. Rats were given 12, 24, or 36 hidden platform training trials. Probe trials with the pool repositioned in the room revealed a preference for place navigation in rats given 12 trials, an equal division of response preferences in rats given 24 trials, and a preference for directional responding in rats given 36 trials. These results indicate that the early preference for place navigation in the full pool water task is transient and yields to a preference for directional responding with continued training
Hubbard, C.E. et Milne-Redhead, E. — Flora of Tropical East Africa. Nouveaux fascicules parus en Avril 1962 : Fumeriaceae, by G. LL Lucas ; Papaveraceae, by G. LL Lucas ; Taccaceae, by S. Carter ; Bruxaceae, by B. Verdcourt ; Theaceae, by B. Verdcourt
No full textBourlière François. Hubbard, C.E. et Milne-Redhead, E. — Flora of Tropical East Africa. Nouveaux fascicules parus en Avril 1962 : Fumeriaceae, by G. LL Lucas ; Papaveraceae, by G. LL Lucas ; Taccaceae, by S. Carter ; Bruxaceae, by B. Verdcourt ; Theaceae, by B. Verdcourt. In: La Terre et La Vie, Revue d'Histoire naturelle, tome 16, n°4, 1962. pp. 450-451
Control of rodent and human spatial navigation by room and apparatus cues
No full textA growing body of literature indicates that rats prefer to navigate in the direction of a goal in the environment (directional responding) rather than to the precise location of the goal (place navigation). This paper provides a brief review of this literature with an emphasis on recent findings in the Morris water task. Four experiments designed to extend this work to humans in a computerized, virtual Morris water task are also described. Special emphasis is devoted to how directional responding and place navigation are influenced by room and apparatus cues, and how these cues control distinct components of navigation to a goal.Experiments 1 and 2 demonstrate that humans, like rats, perform directional responses when cues from the apparatus are present, while Experiment 3 demonstrates that place navigation predominates when apparatus cues are eliminated. In Experiment 4, an eyetracking system measured gaze location in the virtual environment dynamically as participants navigated from a start point to the goal.Participants primarily looked at room cues during the early segment of each trial, but primarily focused on the apparatus as the trial progressed, suggesting distinct, sequential stimulus functions. Implications for computational modeling of navigation in the Morris water task and related tasks are discussed
Spatial exploration patterns determine navigation efficiency: trade-off between memory demands and distance travelled
No full textA total of 41 participants explored a novel square-shaped environment containing five identical boxes each hiding a visually distinct object. After an initial free exploration the participants were required to locate the objects first in a predetermined and subsequently in an optional order task. Two distinct exploration strategies emerged: Participants explored either along the main axes of the room (axial), or in a more spatially spread, circular pattern around the edges of the room (circular). These initial exploration strategies influenced the optimality of spatial navigation performance in the subsequent optional order task. The results reflect a trade-off between memory demands and distance efficiency. The more sequential axial strategy resulted in fewer demands on spatial memory but required more distance to be travelled. The circular strategy was more demanding on memory but required less subsequent travelling distance. The findings are discussed in terms of spatial knowledge acquisition and optimality of strategy representations
Development of composite calibration standard for quantitative NDE by ultrasound and thermography
No full textInspection of aircraft components for damage utilizing ultrasonic Non-Destructive Evaluation (NDE) is a time intensive endeavor. Additional time spent during aircraft inspections translates to added cost to the company performing them, and as such, reducing this expenditure is of great importance. There is also great variance in the calibration samples from one entity to another due to a lack of a common calibration set. By characterizing damage types, we can condense the required calibration sets and reduce the time required to perform calibration while also providing procedures for the fabrication of these standard sets. We present here our effort to fabricate composite samples with known defects and quantify the size and location of defects, such as delaminations, and impact damage. Ultrasonic and Thermographic images are digitally enhanced to accurately measure the damage size. Ultrasonic NDE is compared with thermography.This proceeding may be downloaded for personal use only. Any other use requires prior permission of the author and AIP Publishing.
This proceeding appeared in Dayal, Vinay, Zach G. Benedict, Nishtha Bhatnagar, and Adam G. Harper. "Development of composite calibration standard for quantitative NDE by ultrasound and thermography." In AIP Conference Proceedings, vol. 1949, no. 1, p. 060006. AIP Publishing LLC, 2018, and may be found at
DOI: 10.1063/1.5031552.
Copyright 2018 The Author(s).
Posted with permission
Observations of Bºs→ψ(2S)η and Bº(s)→ψ(2S)π+π- decays
No full textFirst observations of the B0s
→ψ(2S)η, B0 →ψ(2S)π
+
π
− and B0s
→ψ(2S)π
+
π
− decays are made
using a dataset corresponding to an integrated luminosity of 1.0 fb−1 collected by the LHCb experiment in
proton–proton collisions at a centre-of-mass energy of
√
s = 7 TeV. The ratios of the branching fractions
of each of the ψ(2S) modes with respect to the corresponding J/ψ decays are
B(B0s
→ψ(2S)η)
÷
B(B0s
→J/ψη)
= 0.83± 0.14 (stat)±0.12 (syst) ±0.02 (B),
;
B(B0→ψ(2S)π
+
π
−
)
÷
B(B0→J/ψπ
+
π
−
)
= 0.56± 0.07 (stat)±0.05 (syst)± 0.01 (B),
;
B(B0s
→ψ(2S)π
+
π
−
)
÷
B(B0s
→J/ψπ
+
π
−
)
= 0.34± 0.04 (stat)±0.03 (syst)± 0.01 (B),
where the third uncertainty corresponds to the uncertainties of the dilepton branching fractions of the J/ψ
and ψ(2S) meson decays
Treatment-emergent antidrug antibodies related to PD-1, PD-L1, or CTLA-4 inhibitors across tumor types: A systematic review
No full textBackground Increased understanding of how the immune system regulates tumor growth has innovated the use of immunotherapeutics to treat various cancers. The impact of such therapies, including programmed cell death protein 1 (PD-1)/programmed death-ligand 1 (PD-L1) and cytotoxic T-lymphocyte-associated protein 4 (CTLA-4) inhibitors, on the production of antidrug antibodies (ADAs) and their impact on outcomes, is poorly understood. This study aims to evaluate the clinical trial evidence on ADA incidence associated with PD-1, PD-L1, and CTLA-4 inhibitors in the treatment of cancer and to assess associations between treatment administered, ADA incidence, and treatment outcomes. Methods Embase ®, Medline ®, and EBM Reviews were searched via the OVID ® platform on February 15, 2022. Conference proceedings, clinical trial registries, and global regulatory and reimbursement body websites were also searched. Eligible publications included clinical trials enrolling patients receiving cancer treatment with either PD-1, PD-L1, or CTLA-4 reporting outcomes including incidence or prevalence of ADAs and the impact of immunogenicity on treatment safety and efficacy. Reference lists of eligible publications were also searched. The review was conducted and reported according to the Preferred Reporting Items for Systematic Reviews and Meta-Analyses and evidence quality assessment was conducted using the appropriate Joanna Briggs Institute Critical Appraisal tool. Results After screening 4160 records and reviewing 97 full publications, a total of 34 publications reporting on 68 trials were included. A further 41 relevant clinical trials were identified on ClinicalTrials.gov and a further 32 from searches of packaging inserts. In total, 141 relevant trials covering 15 different checkpoint inhibitors and 16 different tumor types were included. Across the included trials, atezolizumab was associated with the highest incidence of ADAs (29.6% of 639 patients), followed by nivolumab (11.2% of 2,085 patients). Combination checkpoint inhibitor treatment appeared to increase the rate of ADAs versus monotherapy. Only 17 trials reported on the impact of ADAs on treatment outcomes with mixed results for the impact of ADAs on treatment efficacy, safety, and pharmacokinetics. Conclusions Checkpoint inhibitors for the treatment of cancer are immunogenic, with the incidence of treatment-emergent ADAs varying between individual therapies. It remains unclear what impact ADAs have on treatment outcomes
Kinetics of Spontaneous and EF-G-Accelerated Rotation of Ribosomal Subunits
No full textSummaryRibosome dynamics play an important role in translation. The rotation of the ribosomal subunits relative to one another is essential for tRNA-mRNA translocation. An important unresolved question is whether subunit rotation limits the rate of translocation. Here, we monitor subunit rotation relative to peptide bond formation and translocation using ensemble kinetics and single-molecule FRET. We observe that spontaneous forward subunit rotation occurs at a rate of 40 s−1, independent of the rate of preceding peptide bond formation. Elongation factor G (EF-G) accelerates forward subunit rotation to 200 s−1. tRNA-mRNA movement is much slower (10–40 s−1), suggesting that forward subunit rotation does not limit the rate of translocation. The transition back to the non-rotated state of the ribosome kinetically coincides with tRNA-mRNA movement. Thus, large-scale movements of the ribosome are intrinsically rapid and gated by its ligands such as EF-G and tRNA
Fluoxetine restores spatial learning but not accelerated forgetting in mesial temporal lobe epilepsy
No full textLearning and memory dysfunction is the most common neuropsychological effect of mesial temporal lobe epilepsy, and because the underlying neurobiology is poorly understood, there are no pharmacological strategies to help restore memory function in these patients. We have demonstrated impairments in the acquisition of an allocentric spatial task, in patients with unilateral hippocampal sclerosis. We also show that patients have accelerated forgetting of the learned spatial task and that this is associated with damage to the non-dominant hippocampal formation. We go on to show a very similar pattern of chronic allocentric learning and accelerated forgetting in a status epilepticus model of mesial temporal lobe epilepsy in rats, which is associated with reduced and abnormal hippocampal neurogenesis. Finally, we show that reversal of the neurogenic deficit using fluoxetine is associated with reversal of the learning deficit but not the accelerated forgetting, pointing to a possible dissociation in the underlying mechanisms, as well as a potential therapeutic strategy for improving hippocampal-dependent learning in patients with mesial temporal lobe epilepsy
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