Pigeons' ability to time light and tone stimuli was examined in four experiments. In Experiment 1, two groups of pigeons were trained to discriminate between 2- and 8-s durations of lights or tones and then were transferred to reversal or nonreversal discriminations in the alternate modality. Pigeons learned the light discrimination faster than the tone discrimination and showed immediate positive intermodal transfer from tone to light but not from light to tone. In Experiments 2-4, the peak procedure was used to study birds' timing of 15- and 30-s fixed-interval light and tone signals. Peak times on empty trials under baseline conditions closely approximated the length of fixed-interval signals. When pigeons were tested with time-outs and intermodal switches introduced midway through an empty trial, they tended to reset the timing mechanism and begin timing again from 0 s. With both estimation and production procedures, pigeons were less accurate when timing the tone stimuli than when timing the light stimuli. A comparison of these data with data from timing experiments with rats suggests several possible differences in timing processes between pigeons and rats.
Background Vascular injury secondary to an acute knee dislocation is a known complication. However, there exist wide discrepancies in the reported rate of vascular injury in this setting. Questions/purposes Using a large private insurance database, we determined the frequency of vascular injury in knee dislocations across year of diagnosis, age, sex, and US geographic region and the proportion of these injuries requiring surgical repair.
MethodsThe PearlDiver database, which contains records from 11 million orthopaedic patients, was searched using ICD-9 diagnostic codes for all knee dislocation events from 2004 to 2009. Within this subset, we identified which knee dislocations had an associated vascular injury ICD-9 code. Patients were stratified by year of diagnosis, age, sex, and US geographic region, and Current Procedural Terminology codes were used to identify the subset of patients with vascular injury requiring surgical repair. Differences in frequency across demographic groups and over time were analyzed with Poisson regression analysis. Results Among the 8050 limbs with knee dislocation identified over the study period, 267 had a concomitant vascular injury for an overall frequency of 3.3%. Males were found to have an increased risk of vascular injury compared to females (odds ratio = 2.59, p \ 0.001). Additionally, patients aged 20 to 39 years had a higher risk of vascular injury when compared to those aged 0 to 19 years (odds ratio = 1.93, p = 0.001), 40 to 59 years (odds ratio = 1.57, p = 0.014), and 60 years or older (odds ratio = 2.81, p = 0.036). There were no differences in vascular injury frequency across US geographic regions or diagnosis year. Thirty-four of the 267 cases of vascular injury (13%) underwent surgical treatment. Conclusions This is the largest study, to our knowledge, that analyzes the proportion of knee dislocations that result in vascular injury. Our data suggest that there is a lower frequency of vascular injury associated with knee
Background: Parkinson's disease, for which currently there is no cure, develops as a result of progressive loss of dopamine neurons in the brain; thus, identification of any potential therapeutic intervention for disease management is of a great importance.
Study Design:Retrospective database study.Objective:Low back and neck pain are among the top leading causes of disability worldwide. The aim of our study was to report the current trends on spine degenerative disorders and their treatments.Methods:Patients diagnosed with lumbar or cervical spine conditions within the orthopedic subset of Medicare and Humana databases (PearlDiver). From the initial cohorts we identified subgroups based on the treatment: fusion or nonoperative within 1 year from diagnosis. Poisson regression was used to determine demographic differences in diagnosis and treatment approaches.Results:Within the Medicare database there were 6 206 578 patients diagnosed with lumbar and 3 156 215 patients diagnosed with cervical degenerative conditions between 2006 and 2012, representing a 16.5% (lumbar) decrease and 11% (cervical) increase in the number of diagnosed patients. There was an increase of 18.5% in the incidence of fusion among lumbar patients. For the Humana data sets there were 1 160 495 patients diagnosed with lumbar and 660 721 patients diagnosed with cervical degenerative disorders from 2008 to 2014. There was a 33% (lumbar) and 42% (cervical) increases in the number of diagnosed patients. However, in both lumbar and cervical groups there was a decrease in the number of surgical and nonoperative treatments.Conclusions:There was an overall increase in both lumbar and cervical conditions, followed by an increase in lumbar fusion procedures within the Medicare database. There is still a burning need to optimize the spine care for the elderly and people in their prime work age to lessen the current national economic burden.
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