323 research outputs found
Regulation of Beta-Adrenergic Adenylate Cyclase Responsiveness of Pig Skin Epidermis by Suboptimal Concentrations of Epinephrine
Although receptor-specific refractoriness has been suggested to be one of the regulatory mechanisms of epidermal adenylate cyclase systems, its physiologic significance has been a subject of controversy because of the requirement of unusually high concentrations of agonists to induce refractoriness. In order to determine whether the epidermal adenylate cyclase system is regulated through a refractoriness mechanism by suboptimal concentrations of receptor agonists, this study was undertaken using pig skin epidermal adenylate cyclase systems.Pretreatment of pig skin with 0.1-1 μM epinephrine in vitro resulted in the reduction of the maximal epinephrine response (epinephrine-induced cyclic AMP accumulations) to various degrees without alterations in either low or high Km, cyclic AMP phosphodiesterase activities. Repeated pretreatments were shown to be more effective in inducing refractoriness than a single pretreatment. Apparently there was no change in the Km value for epinephrine, suggesting that the decrease in epinephrine response represents a reduction in the number but not in the affinity of functional beta-adrenergic adenylate cyclase receptor sites. This refractoriness by low concentrations of catecholamine pretreatment was specific to the beta-adrenergic system, since there was no reduction in histamine response after the epinephrine pretreatment.These results indicate that the epidermal beta-adrenergic adenylate cyclase system is regulated by much lower concentrations of catecholamine than were previously described. It was suggested that physiologic fluctuations of plasma catecholamine levels might have a profound effect on epidermal beta-adrenergic adenylate cyclase responsiveness, resulting in the alteration of the minimal catecholamine level required for the successive activation of cyclic AMP-dependent protein kinase, which is the predominant target of cyclic AMP in epidermis
Effects of Socioeconomic Status on Brain Development, and How Cognitive Neuroscience May Contribute to Levelling the Playing Field
The study of socioeconomic status (SES) and the brain finds itself in a circumstance unusual for Cognitive Neuroscience: large numbers of questions with both practical and scientific importance exist, but they are currently under-researched and ripe for investigation. This review aims to highlight these questions, to outline their potential significance, and to suggest routes by which they might be approached. Although remarkably few neural studies have been carried out so far, there exists a large literature of previous behavioural work. This behavioural research provides an invaluable guide for future neuroimaging work, but also poses an important challenge for it: how can we ensure that the neural data contributes predictive or diagnostic power over and above what can be derived from behaviour alone? We discuss some of the open mechanistic questions which Cognitive Neuroscience may have the power to illuminate, spanning areas including language, numerical cognition, stress, memory, and social influences on learning. These questions have obvious practical and societal significance, but they also bear directly on a set of longstanding questions in basic science: what are the environmental and neural factors which affect the acquisition and retention of declarative and nondeclarative skills? Perhaps the best opportunity for practical and theoretical interests to converge is in the study of interventions. Many interventions aimed at improving the cognitive development of low SES children are currently underway, but almost all are operating without either input from, or study by, the Cognitive Neuroscience community. Given that longitudinal intervention studies are very hard to set up, but can, with proper designs, be ideal tests of causal mechanisms, this area promises exciting opportunities for future research
Issues in NASA program and project management. Special Report: 1993 conference
This volume is the seventh in an ongoing series on aerospace project management at NASA. Articles in this volume cover the 1993 Conference: perspectives in NASA program/project management; the best job in aerospace; improvements in project management at NASA; strategic planning...mapping the way to NASA's future; new NASA procurement initiatives; international cooperation; and industry, government and university partnership. A section on resources for NASA managers rounds out the publication
Graphic Introduction to Problems in Queueing Theory for Architects and Engineers
Architectural Engineerin
Recommended from our members
Narcolepsy : An Interdisciplinary Approach
Narcolepsy is a complex of physiological and behavioral
symptoms. The most striking of these are: excessive daytime
sleepiness, extremely short latency to rapid eye movement (REM)
sleep, hypnogogic hallucinations; sleep paralysis, and cataplexy,
which is loss of skeletal muscle tonus in response to intense
emotions such as surprise, anger, laughter, competition, or sexual
intercourse. What unifies these symptoms is that they are
components of the REM phenomenon and narcolepsy has come to be
known as REM disorder.
The cause(s) of narcolepsy is unknown. A genetic aspect is
possibly involved (Carskadon, 1 982; Guilleminault, 1989) and,
historically, the pandemic encephalitis lethargica resulted in many
reported cases of narcolepsy. Typically, onset of symptoms appear
in teenage years although diagnosis usually takes place many years
after the actual onset (Navelet, 1 976). There are over 200,000
diagonosed cases in the U.S. (Dement, 1979). Studies using lesions
and microelectrode recordings followed by definitive immunohistochemical staining methods have located structures
that are possibly involved in the generation of REM components.
Pharmacological studies complement the neuroanatomical data by
the exogenous induction and suppression of REM and suggest that
the cholinergic and catecholaminergic neurotransmitter systems
are involved. These same systems are implicated in cognitive
behavioral functions of alerting and attention.
Narcoleptics have not been extensively studied with cognitive
testing, despite the fact that their catecholaminergic and
cholinergic systems are impaired as evidenced by the mechanisms
of their effective therapies (Mitler, 1986; Soldatos, 1983; Phillips,
1983) and animal studies of receptor number and serum levels of
neurotransmitter metabolites (Baker and Dement, 1 985; Kilduff et
al., 1986; Faull et a]., 1986). A case study presented in this thesis
attempts to assess the ability of a narcoleptic individual to shift
covert attention, respond to a warning cue and perform an
increasingly difficult response. These tests were given on two
different days. On the first day, the subject was using
protriptyline, a tn-cyclic antidepressant which potentiates the
monoamines and controls cataplexy in the narcoleptic. The second
day of testing took place two months after the subject had taken a
drug holiday from protriptyline. The results may indicate this
individual displays a left hemispheric effect that manifests in
difficulty in disengagement, longer reaction times to contralateral
targets, and slower motor responses. This case study, suggests
future study of cognitive function in the narcolpetic population
Recommended from our members
LCLS XTOD Attenuator System System Concept Report
The attenuator system for the Linac Coherent Light Source (LCLS) X-ray Transport, Optics and Diagnostics (XTOD) system has been configured and analyzed by the Lawrence Livermore National Laboratory's New Technologies Engineering Division (NTED) as requested by the SLAC/LCLS program. The system layout, performance analyses and selection of the vacuum components are presented in this System Conceptual Review (SCR) report. Also included are the plans for prototype, procurement, mechanical integration, and the cost estimates
壁塗り代換に共起する結果述語形容詞の予備調査 : 係り受け解析器を利用した統語構造に基づくデータ抽出の一実践
The University of TokyoThe University of Tokyo会議名: 言語資源活用ワークショップ2021, 開催地: オンライン, 会期: 2021年9月13日-14日, 主催: 国立国語研究所 コーパス開発センター「塗る」のような壁塗り代換を起こす日本語の動詞には,「動作によって移動する移動物」を目的語で表す移動物目的語構文(「壁にペンキを塗る」)と「動作の生じる場所」を目的語で表す場所目的語構文(「壁をペンキで塗る」)がある。両構文に共起する結果述語は,移動物目的語構文内で斜格語を修飾したり(「壁にペンキを【赤く】塗る」),場所目的語構文内で目的語を修飾したり(「ペンキで壁を【赤く】塗る」)して,「場所」の変化を表せる。しかし,同じ叙述対象の状態変化を表す2つの構文がどのように使い分けられるのかは明らかでなく,2つの内いずれが選ばれるのかを機能的に説明する必要がある。そのため,両構文での結果述語が,場所と移動物のどちらの変化を表する傾向が強いか調査する。ここでは,結果述語として形容詞連用形を取り上げ,形容詞が壁塗り代換動詞に係る文を分析する。さらに,「現代日本語書き言葉均衡コーパス」データに係り受け解析器KNPを適用し,統語構造に基づいてデータを抽出した過程も詳述する
Recommended from our members
Testing of vacuum pumps for the Accelerator Production of Tritium/Low Energy Demonstration Accelerator radio frequency quadrupole
Two vacuum systems were designed and built for the RFQ (Radio Frequency Quadrupole) cavity in the APT/LEDA (Low Energy Demonstration Accelerator) linac. The gas load from the proton beam required very high hydrogen pump speed and capacity. The gas load from the high power RF windows also required very high hydrogen pump speed for the RF window vacuum system. Cryopumps were chosen for the RFQ vacuum system and ST185 sintered non-evaporable getter (NEG) cartridges were chosen for the RF window vacuum system. Hydrogen pump speed and capacity measurements were carried out for a commercial cryopump and a NEG pump. This paper will discuss the test procedures and the results of the measurements
The role of the frontal cortex in memory: an investigation of the Von Restorff effect
Evidence from neuropsychology and neuroimaging indicate that the pre-frontal cortex (PFC) plays an important role in human memory. Although frontal patients are able to form new memories, these memories appear qualitatively different from those of controls by lacking distinctiveness. Neuroimaging studies of memory indicate activation in the PFC under deep encoding conditions, and under conditions of semantic elaboration. Based on these results, we hypothesize that the PFC enhances memory by extracting differences and commonalities in the studied material. To test this hypothesis, we carried out an experimental investigation to test the relationship between the PFC-dependent factors and semantic factors associated with common and specific features of words. These experiments were performed using Free-Recall of word lists with healthy adults, exploiting the correlation between PFC function and fluid intelligence. As predicted, a correlation was found between fluid intelligence and the Von-Restorff effect (better memory for semantic isolates, e.g., isolate “cat” within category members of “fruit”). Moreover, memory for the semantic isolate was found to depend on the isolate's serial position. The isolate item tends to be recalled first, in comparison to non-isolates, suggesting that the process interacts with short term memory. These results are captured within a computational model of free recall, which includes a PFC mechanism that is sensitive to both commonality and distinctiveness, sustaining a trade-off between the two
- …