Showing papers by "David W. Johnson published in 1986"
TL;DR: The complete 4,563-amino-acid sequence of apo B-100 precursor (relative molecular mass (Mr) 514,000 (514K)) determined from complementary DNA clones is reported, identifying a domain enriched in basic amino-acid residues as important for the cellular uptake of cholesterol by the LDL receptor pathway.
Abstract: Epidemiological, pathological and genetic studies show a strong positive correlation between elevated plasma concentrations of low-density lipoprotein (LDL) cholesterol and the risk of premature coronary heart disease. Apolipoprotein (apo) B-100 is the sole protein component of LDL and is the ligand responsible for the receptor-mediated uptake and clearance of LDL from the circulation. Apo B-100 is made by the liver and is essential for the assembly of triglyceride-rich very low-density lipoproteins (VLDL) in the cisternae of the endoplasmic reticulum and for their secretion into the plasma. VLDL transports triglyceride to peripheral muscle and adipose tissue, where the triglyceride is hydrolysed by lipoprotein lipase. The resultant particle, relatively enriched in cholesteryl ester, constitutes LDL. LDL delivers cholesterol to peripheral tissues where it is used for membrane and steroid hormone biosynthesis and to the liver, the only organ which can catabolize and excrete cholesterol. Plasma LDL levels are therefore determined by the balance between their rate of production from VLDL and clearance by the hepatic LDL (apo B/E) receptor pathway. Here we report the complete 4,563-amino-acid sequence of apo B-100 precursor (relative molecular mass (Mr) 514,000 (514K] determined from complementary DNA clones. Numerous lipid-binding structures are distributed throughout the extraordinary length of apo B-100 and must underlie its special functions as a nucleus for lipoprotein assembly and maintenance of plasma lipoprotein integrity. A domain enriched in basic amino-acid residues has been identified as important for the cellular uptake of cholesterol by the LDL receptor pathway.
629 citations
Journal Article•
342 citations
TL;DR: The effects of computer-assisted cooperative, competitive, and individualistic instruction were compared on achievement, student-student interaction, and attitudes as mentioned in this paper, finding that computer assisted cooperative instruction promoted greater quantity and quality of daily achievement, more successful problem solving, more task-related studentstudent interaction and increased the perceived status of female students.
Abstract: The effects of computer-assisted cooperative, competitive, and individualistic instruction were compared on achievement, student-student interaction, and attitudes. Seventy-four eighth-grade students were randomly assigned to conditions, stratifying for sex and ability. Computer-assisted cooperative instruction promoted greater quantity and quality of daily achievement, more successful problem solving, more task-related student-student interaction, and increased the perceived status of female students.
257 citations
TL;DR: The essential elements of cooperation learning and the specific actions teachers need to take to implement it are presented in this article.
Abstract: There are three ways in which student-student interaction may be organized for mainstreaming. Of the three, cooperation is the only instructional strategy congruent with the goals of mainstreaming. The essential elements of cooperation learning and the specific actions teachers need to take to implement it are presented in this article. When cooperative learning is implemented effectively, positive relationships between handicapped and nonhandicapped students result. Far more positive interaction between handicapped and nonhandicapped students within instructional situations and during free-time, as well as increased friendships, result from cooperative learning experiences.
174 citations
TL;DR: The effects of cooperative and individualistic learning situations were compared on achievement on a number of tasks representing different levels on Bloom's (1956) taxonomy of cognitive instructional objectives as discussed by the authors.
Abstract: The effects of cooperative and individualistic learning situations were compared on achievement on a number of tasks representing different levels on Bloom's (1956) taxonomy of cognitive instructional objectives. In the cooperative condition, American students worked in small groups to produce a group product and later completed similar tasks as individuals. In the individualistic condition, they worked by themselves to produce individual products and later completed similar tasks as individuals. First-grade students (N = 52) were randomly assigned to conditions stratifying for ability level and sex. The results indicated that on ail tasks, groups achieved more than did individuals, that the higher achievement of students in the cooperative condition transferred to individual testing situations for three higher level reasoning tasks (there were no differences between conditions on two lower level reasoning tasks), and that students in the cooperative condition used higher level reasoning strategi...
139 citations
TL;DR: The impact on achievement of cooperative learning, in which members discussed how well their group was functioning and how they could improve its effectiveness, cooperative learning without any group processing, and individualistic learning were compared on daily achievement, post-instructional achievement, and retention as discussed by the authors.
Abstract: The impact on achievement of (a) cooperative learning, in which members discussed how well their group was functioning and how they could improve its effectiveness, (b) cooperative learning without any group processing, and (c) individualistic learning were compared on daily achievement, postinstructional achievement, and retention. Third-grade American students (N = 84) were randomly assigned to the three conditions, stratifying for sex and ability level. The results indicate that the high-, medium-, and low-achieving students in the cooperation with group processing condition achieved higher on all three measures than did the students in the other two conditions. Students in the cooperation without group processing condition achieved higher on all three measures than did the students in the individualistic condition.
126 citations
TL;DR: In this paper, the effects of positive goal and reward interdependence on student achievement and interpersonal attraction were investigated in a reading class with socially isolated and non-handicapped students.
Abstract: The effects of (a) opportunity to interact with classmates, (b) positive goal interdependence, (c) positive goal and positive reward interdependence, and (d) positive goal and reward interdependence with an added contingency for the use of collaborative skills were investigated. The dependent measures were achievement, interpersonal attraction, and the voluntary use of collaborative skills by socially withdrawn and isolated students. Four socially isolated and withdrawn sixth-grade students (two male and two female) were studied in a reading class. The results indicate that both positive goal and reward interdependence are needed to maximize student achievement and the interpersonal attraction between socially withdrawn and nonhandicapped students. The specific reinforcement for engaging in collaborative skills was required to maximize the voluntary engagement in the skills by socially withdrawn and isolated students.
97 citations
TL;DR: Fatty acids with carbon chain lengths greater than 22 (VLCFA) have been detected in boar, ram, bull and human spermatozoa and polyenoic fatty acids were quantitatively the most important components.
Abstract: Fatty acids with carbon chain lengths greater than 22 (VLCFA) have been detected in boar, ram, bull and human spermatozoa. Saturated and mono-unsaturated fatty acids were present in all spermatozoa but, except for human spermatozoa, polyenoic fatty acids were quantitatively the most important components. Marked differences in polyenoic fatty acid composition were observed. Whereas human spermatozoa contain predominantly di-, tri- and tetraenoic fatty acids with up to 32 carbon atoms, boar, ram and bull spermatozoa also contain pentaenoic and/or hexaenoic acids with up to 34 carbon atoms. Human and boar spermatozoa differ markedly from those of the ram and bull in that only n-6 series acids are present.
91 citations
TL;DR: In this paper, the effects of four conditions were investigated: (a) opportunity to interact with classmates, (b) positive goal interdependence, (c) positive-goal-interdependence with a collaborative-skills group contingency, and (d) positive objective interdependent with both collaborative skills and academic group contingencies.
64 citations
TL;DR: The brains of patients with inherited abnormalities in peroxisomal structure and function contain greatly increased proportions of a homologous series of unique polyenoic fatty acids with carbon chain lengths ranging from 26 to 38 according to evidence by chemical ionization and electron impact mass spectrometry.
Abstract: The brains of patients with inherited abnormalities in peroxisomal structure and function contain greatly increased proportions of a homologous series of unique polyenoic fatty acids with carbon chain lengths ranging from 26 to 38. Based on evidence by chemical ionization and electron impact mass spectrometry before and after catalytic hydrogenation, and argentation t.l.c., these lipids have been tentatively identified as 26:5, 28:5, 30:5, 30:6, 30:7, 32:5, 32:6, 32:7, 34:5 and 34:6 fatty acids. A further two fatty acids eluting at very high temperatures from gas chromatography columns have been tentatively identified on the basis of their chemical ionization mass spectra as 36:6 and 38:6 fatty acids.
TL;DR: The TFTR tokamak has reached its original machine design specifications (Ip=2.5 MA and BT=5.2 T) by operating at low plasma current and low density (ne approximately=1*1019 m-3), high ion temperatures (9+or2 keV) and rotation speeds (7*105 m/s) have been achieved during injection.
Abstract: The TFTR tokamak has reached its original machine design specifications (Ip=2.5 MA and BT=5.2 T). Recently, the D degrees neutral beam heating power has been increased to 6.3 MW. By operating at low plasma current (Ip approximately=0.8 MA) and low density (ne approximately=1*1019 m-3), high ion temperatures (9+or-2 keV) and rotation speeds (7*105 m/s) have been achieved during injection. At the opposite extreme, pellet injection into high current plasmas has been used to increase the line-average density to 8*1019 m-3 and the central density to 1.6*1020 m-3. This wide range of operating conditions has enabled the authors to conduct scaling studies of the global energy confinement time in both ohmically and beam heated discharges as well as more detailed transport studies of the profile dependence.
TL;DR: The results indicated that the combination of group-academic and social-skills contingencies produced in the socially isolated and withdrawn students the highest rates of appropriate social interaction with peers, acceptance and liking by peers, positive attitudes toward the subject area, and achievement.
Abstract: The effects of individual and group contingencies on the achievement and social integration of isolated, learning-disabled students were studied. Five socially isolated and withdrawn eighth-grade students in foreign-language and math classes were subjects. The choice of working alone or in a group with no academic contingency (i.e., bonus points) was compared with working in cooperative learning groups with a group-academic contingency (i.e., bonus points), a group-academic contingency with social-skills training, and a group-academic contingency in combination with a social-skills contingency (i.e., bonus points). The results indicated that the combination of group-academic and social-skills contingencies produced in the socially isolated and withdrawn students the highest rates of appropriate social interaction with peers, acceptance and liking by peers, positive attitudes toward the subject area, and achievement.
TL;DR: An easy and rapid technique using the Mayo Vein Stripper to facilitate safe harvesting of the long saphenous vein for vascular reconstruction provides good quality vein and a superior cosmetic result without wound complications.
Abstract: There is described an easy and rapid technique using the Mayo Vein Stripper to facilitate safe harvesting of the long saphenous vein for vascular reconstruction. It provides good quality vein and a superior cosmetic result without wound complications.
TL;DR: The results indicated that pure cooperation promoted more frequent cross-handicap interaction than did a mixture of cooperation and competition.
Abstract: The effects of different levels of cooperation on cross-handicap interaction were Compared in two studies. In the first study 72 sixth-grade students were randomly assigned to three conditions (cooperative controversy, cooperative debate, and individualistic) stratifying for sex, ability level, and handicap. They participated in the study for 55 minutes a day for 11 instructional days. In the second study, 51 fourth-grade students were randomly assigned to two conditions (intergroup cooperation and intergroup competition) stratifying for sex, ability, and handicap. They participated in the study for 55 minutes a day for 10 instructional days. An Activity Report Scale was given to students to determine who they interacted with in structured class activities, unstructured class activities, school activities outside of class, and activities in the home. The results indicated that pure cooperation promoted more frequent cross-handicap interaction than did a mixture of cooperation and competition. The interact...
TL;DR: In this paper, the authors describe the new components and techniques that have contributed most to improved data quality and reliability in the ten-year evolution of these systems and compare the design parameters of the systems.
Abstract: Thomson scattering systems capable of providing snapshot profiles of electron temperature and density with high spatial resolution (>50 points) have become routine diagnostics on the Princeton large torus (PLT), Princeton divertor experiment (PDX), and tokamak fusion test reactor (TFTR) tokamaks. The design parameters of these systems are compared. Particular attention is given to describing those new components and techniques which have contributed most to improved data quality and reliability in the ten‐year evolution of these systems. Examples of recent TFTR Te(R) and ne(R) profiles are presented.
TL;DR: Threshold data were evaluated by age, sex, and musician-nonmusician categories for the respective frequencies, and data were compared to other studies, suggesting no major hearing loss from musicians' exposure to orchestral noise.
Abstract: Sixty members of the Minnesota Orchestra (aged 24 to 64 years) and 30 nonmusicians (aged 20 to 69 years) were evaluated for hearing sensitivity within the conventional audiometric range (0.25 to 8 kHz) and within the extended high frequency audiometric range (9 to 20 kHz). Threshold data were evaluated by age, sex, and musician-nonmusician categories for the respective frequencies, and data were compared to other studies. Musician hearing appeared no poorer than nonmusician hearing, suggesting no major hearing loss from musicians' exposure to orchestral noise. Hearing acuity of the two groups was similar to some normal groups reported in the world literature but appeared poorer in comparison to some normal groups defined by a very restrictive definition of normal hearing. Issues relating to the definition of normal hearing are explored. A mathematical model descriptive of extended high tone hearing sensitivity for musicians and nonmusicians evaluated was calculated. The formula is presented from which typ...
TL;DR: Assessment of the functional quality of long saphenous vein for coronary revascularization when it has been harvested by means of multiple small incisions and use of the Mayo "stripper" found it to be of good quality and that the intima had been preserved.
TL;DR: The degradation of the superagonist LH-RH analog nafarelin acetate (I) in aqueous solution was followed by reverse-phase HPLC as discussed by the authors, which showed a U-shaped profile with a pH region of maximum stability between pH 4 and 6.
TL;DR: In this article, the evolution and behavior of the electron temperature profile in ohmically heated plasmas in the Tokamak Fusion Test Reactor (TFTR) was studied.
Abstract: Blackbody electron cyclotron emission was used to ascertain and study the evolution and behaviour of the electron temperature profile in ohmically heated plasmas in the Tokamak Fusion Test Reactor (TFTR). The emission was measured with absolutely calibrated millimetre wavelength radiometers. The electron temperature profile normalized to the central temperature and the minor radius was observed to broaden substantially with decreasing limiter safety factor qa and to be insensitive to the plasma minor radius. Sawtooth activity was seen in the core of most TFTR discharges and appeared to be associated with a flattening of the electron temperature profile within the plasma core where q 1. Two types of sawtooth behaviour were identified in large TFTR plasmas (minor radius a 0.8 m): a 'normal' sawtooth with typically 35–40 ms period and a 'compound' sawtooth with 70–80 ms period. The compound sawtooth was characterized by what appeared to be a partial reconnection, which occurs away from the plasma core, in addition to a full reconnection. A multiple linear regression analysis of the central electron temperature Te(0), with toroidal field BT, major radius R, minor radius a, plasma current Ip and effective ion charge Zeff, results in a scaling of the form , for which the major radial dependence was obtained by comparison with earlier PLT data.
TL;DR: Exposure to barley dust and oat dust provoked the greatest number of complaints, and those with a past history of infantile eczema were significantly more likely to complain.
Abstract: 51.4% of 1,954 grain elevator workers surveyed in 1978 and 1979 complained of pruritus following exposure to grain dusts. 95% of 796 grain elevator workers surveyed in 1985 noted that pruritus following exposure to grain dust was of short duration. Exposure to barley dust and oat dust provoked the greatest number of complaints. Those with a past history of infantile eczema were significantly more likely to complain. Younger workers were more likely to complain than older workers. 13.1% of those surveyed in 1985 complained of a rash following exposure, in 35% of whom it lasted more than 1 day. Nasal congestion, ocular and oropharyngeal irritation were also frequent complaints.
TL;DR: Bean-shaped configurations favorable for high .. beta.. discharges have been investigated in the Princeton Beta Experiment (PBX) tokamak and stability analysis implicates the external kink as responsible for the present ..beta.. limit.
Abstract: Bean-shaped configurations favorable for high beta discharges have been investigated in the Princeton Beta Experiment (PBX) tokamak Strongly indented bean-shaped plasmas have been successfully formed, and beta values of over 5% have been obtained with 5 MW of injected neutral beam power These high beta discharges still lie in the first stability regime for ballooning modes, and MHD stability analysis implicates the external kink as responsible for the present beta limit
TL;DR: In this article, the axisymmetric inner toroidal limiter in TFTR was studied and the scaling of the plasma stored energy was studied as a function of the input power, plasma current, and plasma density.
Abstract: The characteristics of plasma operation on the axisymmetric inner toroidal limiter in TFTR are described. After conditioning, plasmas with low metal content and low zeff are obtained with this limiter. There is no substantial increase in zeff with total input power during neutral beam injection. Compared to operation on the outer blade limiter, additional gas is required to fuel plasmas on the inner limiter. Injection of D pellets increased the plasma density substantially and produced energy confinement times up to 0.5 s in ohmically heated plasmas. The four neutral beam lines have injected up to 13.5 MW total power into the plasma for 0.5 s with up to 90 kV accelerating voltage. The scaling of the plasma stored energy was studied as a function of the input power, plasma current and plasma density. In the range 1.4 to 2.2 MA, the overall and incremental confinement times for both the total and thermal stored energies increase with plasma current at fixed density. There appears to be a weak negative scaling of the total stored energy with density at high injection power.
TL;DR: In this paper, a graphite inner-wall belt limiter was used to increase the density and penetration of TFTR pellet injection in plasmas with reduced plasma current and minor and major radius (70 cm and 235 cm).
Abstract: TFTR pellet injection results reported by Schmidt (1985) have been extended to higher density and n tau in plasmas limited by a graphite inner-wall belt limiter. Increased pellet penetration and larger density increases were achieved by operation at reduced plasma current (1.6 MA) and minor and major radius (70 cm and 235 cm). Under these conditions, beam heating results have been extended to 7 MW.
TL;DR: In this article, a system is under construction which makes use of the laser and collection optics of an existing multichannel Thomson scattering system on the tokamak fusion test reactor (TFTR).
Abstract: A system is under construction which will make use of the laser and collection optics of an existing multichannel Thomson scattering system on the tokamak fusion test reactor (TFTR). A scanning sampling mechanism will divert signal from a 10‐cm segment of the radial‐beam path to a spectrometer–detector system which is optimized for low temperatures and densities. In the absence of stray laser light and background plasma light the system will be capable of measuring temperatures down to 3–5 eV at 1–3×1011 cm−3 minimum densities.
TL;DR: The relation between cooperative, competitive, and individualistic attitudes and psychological adjustment and health was examined in dedicated athletes as mentioned in this paper, who were trying out for the 1980 Olympic ice hockey team.
Abstract: The relation between cooperative, competitive, and individualistic attitudes and psychological adjustment and health was examined in dedicated athletes. The respondents were 57 collegiate and semiprofessional ice hockey players who were trying out for the 1980 Olympic ice hockey team. The results indicated that the more cooperatively oriented the athletes, the greater their psychological adjustment and health; competitiveness was unrelated to indexes of psychological adjustment and health; and positive attitudes toward individualistic participation in athletics was correlated with psychological pathology and maladjustment.
TL;DR: The results of a study made to determine the possibility of using the TFTR Thomson scattering system to measure the direction of the local magnetic fields in a tokamak plasma are presented in this paper.
Abstract: The results of a study made to determine the possibility of using the tokamak fusion test reactor (TFTR) Thomson scattering system to measure the direction of the local magnetic fields in a tokamak plasma are presented. We find that it should be possible to measure the q profile for q<1.3 and minor radius <40 cm, with an accuracy of less than 5%.