879 research outputs found
Measuring time perspective in adolescents : can you get the right answer by asking the wrong questions?
Time perspective continues to evolve as a psychological construct. The extant literature suggests that higher future orientation and lower present orientation are associated with better developmental outcomes. However, the extant literature also suggests that issues remain with the measurement of the construct. Recently, a 25-item version of the Zimbardo Time Perspective Inventory (ZTPI-25) was suggested for use based on high internal consistency estimates and good discriminant validity of scores in a sample of Italian adolescents. However, the genesis of this scale is uncertain. The present study examined the factorial validity, reliability, and concurrent validity of ZTPI-25 scores in Slovenian, American, and British adolescents. Results revealed satisfactory concurrent validity based on correlations with measures used in the development of the full ZTPI. However, internal consistency and factorial validity of scores were unsatisfactory. The present study questions the use of the ZTPI-25 with adolescents in the context of conceptual and measurement issues more broadly
What's Decidable about Discrete Linear Dynamical Systems?
We survey the state of the art on the algorithmic analysis of discrete linear dynamical systems, and outline a number of research directions
Impact of Crural Relaxing Incisions, Collis Gastroplasty, and Non–Cross-linked Human Dermal Mesh Crural Reinforcement on Early Hiatal Hernia Recurrence Rates
BackgroundHernia recurrence is the leading form of failure after antireflux surgery and may be secondary to unrecognized tension on the crural repair or from a foreshortened esophagus. Mesh reinforcement has proven beneficial for repair of hernias at other sites, but the use of mesh at the hiatus remains controversial. The aim of this study was to evaluate the outcomes of hiatal hernia repair with human dermal mesh reinforcement of the crural closure in combination with tension reduction techniques when necessary.Study DesignWe retrospectively reviewed the records of all patients who had hiatal hernia repair using AlloMax Surgical Graft (Davol), a human dermal biologic mesh. Objective follow-up was with videoesophagram and/or upper endoscopy at 3 months postoperatively and annually.ResultsThere were 82 patients with a median age of 63 years. The majority of operations (85%) were laparoscopic primary repairs of a paraesophageal hernia with a fundoplication. The crura were closed primarily in all patients and reinforced with an AlloMax Surgical Graft. A crural relaxing incision was used in 12% and a Collis gastroplasty in 28% of patients. There was no mesh-related morbidity and no mortality. Median objective follow-up was 5 months, but 15 patients had follow-up at 1 or more years. A recurrent hernia was found in 3 patients (4%).ConclusionsTension-reducing techniques in combination with human biologic mesh crural reinforcement provide excellent early results with no mesh-related complications. Long-term follow-up will define the role of these techniques and this biologic mesh for hiatal hernia repair
On Reachability Problems for Low-Dimensional Matrix Semigroup
We consider the Membership and the Half-Space Reachability problems for matrices in dimensions two and three. Our first main result is that the Membership Problem is decidable for finitely generated sub-semigroups of the Heisenberg group over rational numbers. Furthermore, we prove two decidability results for the Half-Space Reachability Problem. Namely, we show that this problem is decidable for sub-semigroups of GL(2,Z) and of the Heisenberg group over rational numbers
Toward a fully implantable ecosystem for adaptive neuromodulation in humans: Preliminary experience with the CorTec BrainInterchange device in a canine model
This article describes initial work toward an ecosystem for adaptive neuromodulation in humans by documenting the experience of implanting CorTec\u27s BrainInterchange (BIC) device in a beagle canine and using the BCI2000 environment to interact with the BIC device. It begins with laying out the substantial opportunity presented by a useful, easy-to-use, and widely available hardware/software ecosystem in the current landscape of the field of adaptive neuromodulation, and then describes experience with implantation, software integration, and post-surgical validation of recording of brain signals and implant parameters. Initial experience suggests that the hardware capabilities of the BIC device are fully supported by BCI2000, and that the BIC/BCI2000 device can record and process brain signals during free behavior. With further development and validation, the BIC/BCI2000 ecosystem could become an important tool for research into new adaptive neuromodulation protocols in humans
Electrical Stimulation Modulates High γ Activity and Human Memory Performance.
Direct electrical stimulation of the brain has emerged as a powerful treatment for multiple neurological diseases, and as a potential technique to enhance human cognition. Despite its application in a range of brain disorders, it remains unclear how stimulation of discrete brain areas affects memory performance and the underlying electrophysiological activities. Here, we investigated the effect of direct electrical stimulation in four brain regions known to support declarative memory: hippocampus (HP), parahippocampal region (PH) neocortex, prefrontal cortex (PF), and lateral temporal cortex (TC). Intracranial EEG recordings with stimulation were collected from 22 patients during performance of verbal memory tasks. We found that high γ (62-118 Hz) activity induced by word presentation was modulated by electrical stimulation. This modulatory effect was greatest for trials with poor memory encoding. The high γ modulation correlated with the behavioral effect of stimulation in a given brain region: it was negative, i.e., the induced high γ activity was decreased, in the regions where stimulation decreased memory performance, and positive in the lateral TC where memory enhancement was observed. Our results suggest that the effect of electrical stimulation on high γ activity induced by word presentation may be a useful biomarker for mapping memory networks and guiding therapeutic brain stimulation
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Human Verbal Memory Encoding Is Hierarchically Distributed in a Continuous Processing Stream.
Processing of memory is supported by coordinated activity in a network of sensory, association, and motor brain regions. It remains a major challenge to determine where memory is encoded for later retrieval. Here, we used direct intracranial brain recordings from epilepsy patients performing free recall tasks to determine the temporal pattern and anatomical distribution of verbal memory encoding across the entire human cortex. High γ frequency activity (65-115 Hz) showed consistent power responses during encoding of subsequently recalled and forgotten words on a subset of electrodes localized in 16 distinct cortical areas activated in the tasks. More of the high γ power during word encoding, and less power before and after the word presentation, was characteristic of successful recall and observed across multiple brain regions. Latencies of the induced power changes and this subsequent memory effect (SME) between the recalled and forgotten words followed an anatomical sequence from visual to prefrontal cortical areas. Finally, the magnitude of the memory effect was unexpectedly found to be the largest in selected brain regions both at the top and at the bottom of the processing stream. These included the language processing areas of the prefrontal cortex and the early visual areas at the junction of the occipital and temporal lobes. Our results provide evidence for distributed encoding of verbal memory organized along a hierarchical posterior-to-anterior processing stream
2014 Epilepsy Benchmarks Area III: Improve Treatment Options for Controlling Seizures and Epilepsy-Related Conditions Without Side Effects
The Epilepsy Benchmark goals in Area III focus on making progress in understanding and controlling seizures and related conditions as well as on developing biomarkers and new therapies that will reduce seizures and improve outcomes for individuals with epilepsy. Area III emphasizes a need to better understand the ways in which seizures start, propagate, and terminate and whether those network processes are common or unique in different forms of epilepsy. The application of that knowledge to improved seizure prediction and detection will also play a role in improving patient outcomes. Animal models of treatment-resistant epilepsy that are aligned with etiologies and clinical features of human epilepsies are especially encouraged as necessary tools to understand mechanisms and test potential therapies. Antiseizure therapies that target (either alone or in combination) novel or multiple seizure mechanisms are prioritized in this section of the Benchmarks. Area III goals also highlight validation of biomarkers of treatment response and safety risk, effective self-management, and patient-centered outcome measures as important areas of emphasis for the next five to ten years
Liquid State Anomalies for the Stell-Hemmer Core-Softened Potential
We study the Stell-Hemmer potential using both analytic (exact and
approximate ) solutions and numerical simulations. We observe in the
liquid phase an anomalous decrease in specific volume and isothermal
compressibility upon heating, and an anomalous increase in the diffusion
coefficient with pressure. We relate the anomalies to the existence of two
different local structures in the liquid phase. Our results are consistent with
the possibility of a low temperature/high pressure liquid-liquid phase
transition.Comment: 4 pages in one gzipped ps file including 11 figures; One RevTex and
11 gzipped eps figure
A motor association area in the depths of the central sulcus
Cells in the precentral gyrus directly send signals to the periphery to generate movement and are principally organized as a topological map of the body. We find that movement-induced electrophysiological responses from depth electrodes extend this map three-dimensionally throughout the gyrus. Unexpectedly, this organization is interrupted by a previously undescribed motor association area in the depths of the midlateral aspect of the central sulcus. This \u27Rolandic motor association\u27 (RMA) area is active during movements of different body parts from both sides of the body and may be important for coordinating complex behaviors
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