The relationship between surface potentials and the number of active motor units

One of the assumptions inherent in a technique recently devised for enumerating motor units in human muscles is that the surface potentials from active motor units summate in a linear fashion. We present an electrical model of a muscle which predicts that a linear relationship between the number of active units and the electrical response recorded at the surface overlying the muscle would not be expected. The extent of the non-linearity, and hence the error in the calculation of the number of motor units in a given muscle, depends upon the ratio between the mean conductance of the motor units themselves and that of the external conduction pathway through which the electrical signal is fed (Gu/Ge). The extent of non-linearity is assessed experimentally in human hypothenar muscles using a "collision" technique. The average underestimate introduced into the calculation of the number of motor units in this particular case was concluded to be 26%. The value of Gu/Ge derived from these experiments, in 2 subjects, was checked by simulating an intramuscular action potential and determining the attenuation at the surface. The 2 independently obtained values were sufficiently close to suggest that the model may be a valid one. We conclude that caution should be employed in the interpretation of experiments which purport to determine the number of motor units in a muscle by means of surface recordings.     

Relationship between individual proficiency and team performance and efficiency.

Using 64 pairs of college students doing jigsaw puzzles, team and individual performance was compared. They could work the puzzles better alone than when doing it in pairs cooperatively, however, relatively poor prediction is obtained from measures of individual proficiency. The performance of the most efficient member of a team, however, predicted slightly better both team performance and team efficiency. "The more similar the two members of a team were in individual proficiency, the more likely they were to form a proficient and effective team." (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

The relationship between cooling rate and age-hardening characteristics of a number of aluminum-magnesium-silicide alloys

Abstract

The effect of cooling rate from solution heat treatment on the response to elevated temperature age-hardening of many technical and commercial magnesium-silicide alloys was determined in terms of a full range of cooling rates and tensile properties. The effect of individual minor element additions on the relationship was determined and an interpretation made in terms of the microstructure. From the data obtained it is possible to specify the precise cooling rate or combination of cooling rate and ageing procedure necessary to achieve a desired level of tensile properties. Where the mass of the metal places a limitation on the cooling rate the data make it possible to consider alternative alloys or additions to meet the tensile requirements.

Résumé

Les effets de la vitesse de trempe à partir du traitement de mise en solution sur le vieillissement à haute température d'un certain nombre d'alliages commerciaux ou synthétiques Aluminium — Magnésium — Silicium ont été étudiés par mesure des propriétés mécaniques en traction. L'auteur a étudié l'effet d' éléments d'addition mineurs sur la relation vitesse de trempe-propriétés mécaniques et présente une interprétation basée sur la microstructure.

A partir des résultats obtenus, il est possible de déterminer avec précision la vitesse de trempe ou la combinaison vitesse de trempe-conditions de vieillissement, nécessaires pour obtenir des propriétés mécaniques données. Lorsque la masse de métal impose une limitation à la vitesse de trempe, les résultats expérimentaux permettent de sélectionner d'autres alliages ou les additions nécessaires pour obtenir les propriétés mécaniques requises.     

The moderating roles of self-esteem and neuroticism in the relationship between group and individual undermining behavior.

The authors developed and tested a multilevel interactive model of the relationship between group undermining and individual undermining behavior in 2 multiwave studies of group members. Integrating the literature on group influences on individual behavior with the individual difference literature, the authors predicted a 3-way Group Undermining × Self-Esteem × Neuroticism interaction, such that the relationship between group and individual undermining would be strongest among those simultaneously high in self-esteem and neuroticism. The 3-way interaction was supported in Study 1 (457 participants in 103 groups) and replicated in Study 2 (415 participants in 93 groups) with additional controls and alternative measures of key constructs. The authors discuss the implications of the research and identify future research directions. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Understanding the relationship between moral judgment development and individual characteristics: The role of educational contexts.

This study examines variation in moral judgment level as measured by the Defining Issues Test 2 (DIT-2; J. R. Rest & D. Narvaez, 1998), based on individual demographic information and educational contexts. Individual DIT-2 scores and demographic information were obtained from the archived data sets housed at the Center for the Study of Ethical Development. The information on educational contexts was obtained by surveying the researchers who initially gathered the data. Hierarchical linear modeling was used to analyze DIT-2 data from 7,642 individuals and 65 institutions. Findings indicate that average DIT-2 scores vary significantly among institutions. Further, the authors found that the strength of the relation of DIT-2 scores to gender and English language status is significant and consistent across contexts, whereas the strength of the relation to educational level and political identity varies across contexts. These findings indicate that information about the individuals' educational context as well as the broader regional contexts should be taken into account to understand variation in individual levels of moral judgment. The findings can also be used as an interpretive guide for DIT-2 users. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

On the relationship between synaptic input and spike output jitter in individual neurons

What is the relationship between the temporal jitter in the arrival times of individual synaptic inputs to a neuron and the resultant jitter in its output spike? We report that the rise time of firing rates of cells in striate and extrastriate visual cortex in the macaque monkey remain equally sharp at different stages of processing. Furthermore, as observed by others, multiunit recordings from single units in the primate frontal lobe reveal a strong peak in their cross-correlation in the 10-150 msec range with very small temporal jitter (on the order of 1 msec). We explain these results using numerical models to study the relationship between the temporal jitter in excitatory and inhibitory synaptic input and the variability in the spike output timing in integrate-and-fire units and in a biophysically and anatomically detailed model of a cortical pyramidal cell. We conclude that under physiological circumstances, the standard deviation in the output jitter is linearly related to the standard deviation in the input jitter, with a constant of less than one. Thus, the timing jitter in successive layers of such neurons will converge to a small value dictated by the jitter in axonal propagation times.     

The relationship between adult attachment style and therapeutic alliance in individual psychotherapy: A meta-analytic review.

The present study examined the relationship between adult attachment style and therapeutic alliance in individual psychotherapy. Search procedures yielded 17 independent samples (total N = 886, average n = 52, standard deviation = 24) for inclusion in the meta-analysis. Results indicated that greater attachment security was associated with stronger therapeutic alliances, whereas greater attachment insecurity was associated with weaker therapeutic alliances, with an overall weighted effect size of r = .17, p .10) with the exception of the source of alliance ratings; results indicated that patient-rated alliance demonstrated a significantly larger relationship with attachment compared with therapist-rated alliance (Qbetween = 3.95, df = 1, p = .047). Implications for clinical practice and future research are discussed. (PsycINFO Database Record (c) 2011 APA, all rights reserved)     

Evaluation of different protocols for prostaglandin synchronization to improve reproductive performance in dairy herds with low estrus detection efficiency

The objective of this study was to evaluate different PGF2 alpha protocols against control protocols for herds with estrus detection efficiencies of 35, 55, and 75% using modeling and simulation: 1) PGF2 alpha treatments based on the presence of a corpus luteum diagnosed by rectal palpation, 2) PGF2 alpha treatments based on the presence of a corpus luteum diagnosed by an on-farm milk progesterone enzyme immunoassay, and 3) PGF2 alpha treatments based on a 14-d fixed treatment schedule without prior screening for ovarian status. After the start of each protocol, estrus detection efficiency was 75% for 7 d after treatment and 35 or 0% for the following week. For the third protocol, an additional modification at estrus detection efficiencies of 85 and 55%, respectively, in the 1st and 2nd wk after treatment was evaluated to establish a protocol for best case assumptions. All protocols improved reproductive performance relative to that of controls with estrus detection efficiencies of 35 and 55%. The mean number of days open was reduced from 124.3 d in the control herd to 95.9, 95.0, and 92.7 for the protocols based on rectal palpation, milk progesterone test, and the fixed treatment schedule, respectively. The protocols based on a fixed treatment schedule were superior to protocols based on rectal palpation and on-farm milk progesterone tests and resulted in better reproductive performance and a higher increase in net return per cow per year. Relative to a control herd with an estrus detection efficiency of 55%, it was cost effective to spend up to $10 per dose of PGF2 alpha, $9 per milk progesterone test, and $6 per rectal palpation.     

Associations between use of electric cow-trainers and clinical diseases, reproductive performance and culling in Swedish dairy cattle

The aims of this follow-up study were: (a) to evaluate the role of ECT technology as a risk factor for several diseases; and (b) to determine if the effects of these diseases on cows' reproductive performance and as risk factors for culling are influenced by exposure to ECTs. Diseases considered were retained placenta, metritis, ketosis, cystic ovaries, silent heat, milk fever, clinical mastitis, and foot and leg problems. We used historical and contemporary controls (with control herds selected to match the experimental herds for size and location). Data consisted of 10,264 Swedish Red and White (SRB) and 5461 Swedish Friesian (SLB) lactation records in 150 herds of which 33 used cow-trainers. Logistic regression was used to estimate the effects of parity and exposure to electric cow-trainers on the risks of diseases and the effects of diseases and exposure to electric cow-trainers on risk of culling. The least-squares procedure was used to estimate the effects of diseases on reproductive performance. The dominant effects associated with use of electric cow-trainers were an increased risk for silent heat, clinical mastitis, ketosis and culling relative to cows in herds not using cow-trainers. Diseases had negative effects on reproductive performance and the effects were larger for cows in herds using cow-trainers. In herds using electric cow-trainers, the largest increase in the interval from first service to conception (58 days) was caused by the occurrences of silent heat, cystic ovaries and the combination of two or more diseases. Retained placenta, metritis, cystic ovaries, clinical mastitis and a combination of two or more diseases increased the risk of culling about two times relative to healthy primiparous cows with the increase being greater for cows in herds using cow-trainers. Silent heat did not increase risk of culling in control groups, but was the largest risk factor for culling in the exposed group. We concluded that exposure to electric cow-trainers increased the incidence risk of silent heat, clinical mastitis, and ketosis and changed silent heat from a neutral disease with respect to culling to a major risk factor. Finally, exposure to cow-trainers increased the general negative effect of diseases on the cows' reproductive performance and risk for culling.     

On the relationship between EEG and P300: individual differences, aging, and ultradian rhythms

The literature on the relationship between background EEG and event-related brain potentials (ERPs) is reviewed, with the conclusion that variation in the former can contribute to individual variability in the latter. The effects of background EEG activity on the P300 component are then described using the results of three experiments. Study 1 assayed the association between EEG spectral power/mean frequency and P300 amplitude/latency measures in young adults. For the slower delta, theta, and alpha bands generally strong correlations who obtained for both types of measures. Study 2 employed similar techniques to assess a large sample of adults who varied in age from 20-80+ years. EEG power in the slower bands was correlated positively with P300 amplitude across the age range, but few effects for mean frequency/component latency were observed. Study 3 measured a group of young adults ten times very 20 min to assess for temporal changes in the relationship between EEG and ERPs. The correlations between spectral power and P300 amplitude measures were found to vary in a manner that suggested the influence of ultradian rhythms on neuroelectric activity. Taken together, the findings from all three study indicate that background EEG variation contributes significantly to the individual variability of the P300 ERP. Theoretical and applied implications of the findings are discussed.     

The relationship between microstructure and the J-R curve

A model is presented that establishes a quantitative relationship between the J _IC and the J-R curve and the microstructural parameters, such as inclusion size and spacing, and the plastic deformation properties of ductile materials, such as yield strength and strain hardening exponents. The model assumes that ductile crack growth occurs by void nucleation, growth, and coalescence. Each of these processes is modeled in the crack tip environment to complete the model. The proposed model is evaluated using tests performed on 303 stainless steel (SS) at room temperature and on 1Cr-Mo-0.25V steel at 565 °C. Satisfactory agreements are obtained between the experimentally obtained J-R curves and those predicted from the model. Limitations of the model are also discussed.     

Personality, motivation, and performance: A theory of the relationship between individual differences and information processing.

Presents a model to relate the personality dimensions of introversion–extraversion, achievement motivation, and anxiety to efficient cognitive performance. It is demonstrated how these personality dimensions in combination with situational moderators (e.g., success, failure, time pressure, incentives, time of day, stimulant drugs) affect the motivational constructs of arousal and effort. A general information-processing model that accounts for the systematic effects of these motivational states on certain task components (sustained information transfer and some aspect of short-term memory) is proposed. Empirical generalizations about task components in a structural model are combined, and testable predictions that differentiate alternative motivational hypotheses are derived. (132 ref) (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Effects of a duodenal glucose infusion on the relationship between plasma concentrations of glucose and insulin in dairy cows

The effects of duodenal infusion of glucose on the relationship between plasma concentrations of glucose and insulin and on milk composition were investigated in a crossover design. Eight dairy cows were continually infused with water (control) or glucose (1.5 kg/d). Cows received diets consisting of dehydrated whole-plant maize in restricted amounts to equalize the energy supply between treatments. Basal (before meal) plasma concentrations of glucose and insulin were increased, but concentrations of nonesterified fatty acids (NEFA) were decreased, by glucose treatment. During the first 2 h after feed distribution, plasma insulin increased, and plasma glucose and NEFA decreased, in both control and treated cows. Afterward, plasma glucose increased in treated cows but further decreased in control cows. The difference reached 8 mg/100 ml without any change in plasma insulin. During the meal, concentrations of growth hormones in plasma were inhibited to a similar extent in both groups. In response to intravenous glucose or insulin challenges, changes in plasma glucose, NEFA, and insulin stimulated by glucose were also very similar in both groups. In conclusion, duodenal infusion of glucose increased basal plasma concentrations of glucose and insulin, increased postprandial plasma glucose, and decreased NEFA without inducing insulin resistance. Glucose treatment did not change milk yield but decreased milk fat yield, mainly through a decrease in the yield of C18 fatty acids that were derived from circulating fatty acids. In the absence of insulin resistance, the decrease in the yield of C18 fatty acids might be attributed to an inhibition of adipose lipolysis or an increase in adipose lipogenesis.     

The relationship between osteoarthritis and osteoporosis in the spine

We report on the case of a man, whose psychopathological symptoms markedly varied during different phases of his illness, causing difficulties in applying common diagnostic criteria for schizophrenia. Depending upon each of the predominant symptoms, this resulted in different diagnoses and therapeutic strategies. We also discuss the importance of obsessions and compulsions in differential diagnosis in this case.     

The relationship between humor and the expression of hostility.

This study explored the relationships among the expression of hostility in behavior, the extent to which hostile cartoons are judged funny, and the ability to recognize hostility in cartoons. 3 groups of 15 male psychiatric patients each were rated as expressing hostility overtly, covertly, or not at all. They were asked to judge the funniness of 32 cartoons and also to indicate which of the cartoons expressed hostility and which did not. Relationships were found between the expression of hostility and the tendency to judge hostile cartoons as funny, between estimated IQ and the ability to differentiate hostile and non-hostile cartoons, between the expression of hostility and the differentiation of hostile and non-hostile cartoons, and between the tendency to judge hostile cartoons as funny and the ability to differentiate hostile and non-hostile cartoons. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

图书馆制度与图书馆发展关系论

图书馆制度包括宏观政策工作规程和个馆微观工作规则,它们与图书馆的发展密切相关,宏观规程指导图书馆事业发展方向,加大图书馆建设发展力度,确保图书馆文化的延续与发展;微观工作规则保证了图书馆各项工作的顺利进行,加强高校图书馆法规制度建设,将会在今后的自动化、网络化、现代化建设中发挥重要作用。     

An analysis of the relationship between grain size,solute content,and the potency and number density of nucleant particles

To be able to determine the grain size obtained from the addition of a grain refining master alloy, the relationship between grain size (d), solute content (defined by the growth restriction factor Q), and the potency and number density of nucleant particles needs to be understood. A study was undertaken on aluminium alloys where additions of TiB₂ and Ti were made to eight wrought aluminum alloys covering a range of alloying elements and compositions. It was found from analysis of the data that . From consideration of the experimental data and from further analysis of previously published data, it is shown that the coefficients a and b relate to characteristics of the nucleant particles added by a grain refiner. The term a is related to the maximum density of active TiB₂ nucleant particles within the melt, while b is related to their potency. By using the analysis methodology presented in this article, the performance characteristics of different master alloys were defined and the effects of Zr and Si on the poisoning of grain refinement were illustrated.     

The relationship between hepatoma and portal vein

Hepatic cells receive dual blood supply of the arterial and portal systems, but hepatoma has been thought to be supplied completely by hepatic artery. However, transcatheter hepatic artery embolization (TAE) has not been able to damage hepatoma entirely. For the study on the relationship between hepatoma and portal vein, I gave intraportal infusions of bromodeoxyuridine. (BrdU), an analogue of thymidine, to 10 patients with hepatoma at the time of surgery, and counted BrdU-positive nuclei immunohistochemically using the anti-BrdU monoclonal antibody. The labeling index, or percentage of BrdU-labelled cells, was 2.0 +/- 1.1% (mean +/- SD) in the cases without TAE and 11.9 +/- 4.2% in the other after TAE. On the other hand, examining the specimens with Microfil injected into the portal branch showed the distribution of portal branches in the hepatoma by radiograph or microscope. It is concluded that hepatoma does not receive arterial blood supply alone but the portal vein participates in vascular distribution of hepatoma, and the participation gets larger after TAE. It is suggested that this finding could be of great importance in planing treatment of patients with hepatoma.