Dispersion Size-Consistency

A multivariate adiabatic connection (MAC) framework for describing dispersion interactions in a system consisting of non-overlapping monomers is presented. By constraining the density to the physical ground-state density of the supersystem, the MAC enables a rigorous separation of induction and dispersion effects. The exact dispersion energy is obtained from the zero-temperature fluctuation-dissipation theorem and partitioned into increments corresponding to the interaction energy gained when an additional monomer is added to a -monomer system. The total dispersion energy of an -monomer system is independent of any partitioning into subsystems. This statement of dispersion size consistency is shown to be an exact constraint. The resulting additive separability of the dispersion energy results from multiplicative separability of the generalized screening factor defined as the inverse generalized dielectric function. Many-body perturbation theory (MBPT) is found to violate dispersion size-consistency because perturbative approximations to the generalized screening factor are nonseparable; on the other hand, random phase approximation-type methods produce separable generalized screening factors and therefore preserve dispersion size-consistency. This result further explains the previously observed increase in relative errors of MBPT for dispersion interactions as the system size increases. Implications for electronic structure theory and applications to supramolecular materials and condensed matter are discussed.

The Symmetry of Lower Back Pain as a Potential Screening Factor for Serious Pathology: A Survey Study

Background: Pain maps provide reliable information on pain location in various conditions. This study explored the feasibility of pain maps as a screening tools for serious underlying conditions. The pain symmetry was evaluated as the possible distinguishing feature. Methods: A Web-based survey on the correlation of pain-related disability and pain pattern was developed. Respondents with lower back pain were asked to mark the exact location of their pain over the pain chart. The symmetry index was calculated and used to divide subjects into two groups that were then compared in terms of the prevalence of red flags for serious pathologies, as well as the pain-related disability measured with COMI and ODI instruments. Results: Of the 4213 respondents who completed the survey, 1018 were included in the study. The pain related disability was greater in respondents with asymmetrical pain patterns, as shown with all instruments. The distribution of red flags was also dependent on pain symmetry. The history of weight loss (6.70 vs. 1.76 p < 0.001) and fever (4.91 vs. 2.14 p < 0.001) were more prevalent with symmetrical pain patterns, and the history of trauma was more frequent with asymmetrical pain (21.41 vs. 10.71 p < 0.001). Conclusions: It was shown that the symmetry of pain is correlated to the prevalence of red flags and pain-related disability.

Factors of influence on sharing of cultural heritage knowledge

Purpose Knowledge sharing is influenced by various factors in different cultures. It is imperative to understand those factors that influence knowledge sharing, therefore, this paper aims to examine the factors that influence cultural heritage knowledge (CHK) sharing. Design/methodology/approach Data was collected from 400 Tangkhul youth from Manipur state through a survey-based questionnaire. Data screening, factor analysis and reliability tests were carried out to confirm the validity and reliability of the instruments, t-test and ANOVA test were carried out to check the stated hypotheses. Findings From factor analysis, six factors i.e. rewards, intention to share, expect a relationship, enjoy helping, self-efficacy and reciprocity, were identified which are influencing knowledge sharing. The study indicates that “rewards” and “intention to share” are the two most vital factors influencing the individuals to share their CHK. The results show that “rewards” have a significant difference on gender and place of residence [(t = 3.153, p = 0.002) and (t = 2.500, p = 0.013)] also “enjoy helping” has a significant difference on the subject background (F = 3.185, p = 0.024) and “reciprocity” and “intention to share” has a significant difference on family income [(F= 3.270, p = 0.007) and (F = 2.716, p = 0.020)]. Originality/value This study determines to identify the various factors that are influencing on sharing of CHK among the Tangkhul youth. It is found that reward was the prime factor in sharing CHK among the Tangkhul youth.

Multiscale analysis of hydrogen-induced softening in f.c.c. nickel single crystals oriented for multiple-slips: elastic screening effect

Hydrogen-deformation interactions and their role in plasticity are well accepted as key features in understanding hydrogen embrittlement. In order to understand the nature of the hydrogen-induced softening process in f.c.c. metals, a substantial effort was made in this study to determine the effect of hydrogen on the tensile stress-strain behavior of nickel single crystal oriented for multiple-slips. It was clearly established that the hydrogen softening process was the result of a shielding of the elastic interactions at different scales. Hydrogen-induced softening was then formalized by a screening factor S of 0.8 ± 0.05 for 7 wppm of hydrogen, which can be incorporated into standard dislocation theory processes. The amplitude of softening suggests that the shielding process is mainly responsible for the stress softening through the formation of vacancy clusters, rather than a direct impact of hydrogen. This effect is expected to be of major importance when revisiting the impact of hydrogen on the processes causing damage to the structural alloys used in engineering.

Optimization of Chitinase Production by Trichoderma virens in Solid State Fermentation Using Response Surface Methodology

Physical factor for chitinase production by Trichodermavirens was first carried out using screening factor of 2-level factorial. The design was employed by selecting incubation time, temperature, moisture substrate, pH, inoculums size and concentration ammonium sulphate as a model factors. The result of 2-level factorial design experiment showed thal all three independent variable have significant effect on chitinase production. The physical factor was further optimized using Central Composite Design in which response surface was generated later from the derived model. An experimental design of three variables including various incubation time, temperature and moisture substrate were created using Design Expert® Software, Version 6.0.4 The design consist of 20 experiments, which include 6 replicate at center points. The optimal value for each variable are incubation time sixth days, temperature 27.83°C and moisture substrate 54% with predicted chitinase activity of 0.48738 U/g of dry substrate. These predicted parameters were tested in the laboratory and the final chitinase activity obtained was 0.48864 U/g of dry substrate, which is similar to the predicted value. The obtained value of the chitinase production was 0.48738 U/g IDS, which was 1.2 fold higher than that of the 2-level factorial design (0.261 U/gds)

Runoff Prediction Method Based on Adaptive Elman Neural Network

The prediction of medium- and long-term runoff is of great significance to the comprehensive utilization of water resources. Building an adaptive data-driven runoff prediction model by automatic identification of multivariate time series change in runoff forecasting and identifying its influence degree is an attractive and intricate task. At present, the commonly used screening factor method is correlational analysis; others offer multi-collinearity. If these factors are directly input into the model, the parameters of the model tend to increase, and the excessive redundancy and noise adversely affects the prediction results of the model. On the basis of previous studies on medium- and long-term runoff prediction methods, this paper proposes an Elman Neural Network (ENN) adaptive runoff prediction method based on normalized mutual information (NMI) and kernel principal component analysis (KPCA). In this method, the features of the screening factors are extracted automatically by using the mutual information automatic screening factor, and then input into the Elman Neural Network for training. With less features, the parameters of the Elman Neural Network model can be reduced, and the problem of overfitting of the Elman Neural Network model is effectively alleviated. The method is evaluated by using the annual average runoff data of Jinping hydropower station in Chengdu, China, from 2007 to 2011. The maximum relative error of multiple forecasts was found to be less than 16%, and forecast effect was good. The accuracy of prediction is further improved by averaging the results of multiple forecasts.

Magnetospheric radius of an inclined rotator in the magnetically threaded disk model

The estimate of the magnetospheric radius in a disk-fed neutron star X-ray binary is a long standing problem in high energy astrophysics. We have reviewed the magnetospheric radius calculations in the so-called magnetically threaded disk model, comparing the simplified approach originally proposed by Ghosh & Lamb (1979, ApJ, 232, 259) with the revised version proposed by Wang (1987, A&A, 183, 257), Wang (1995, ApJ, 449, L153), and Wang (1997, ApJ, 475, L135). We show that for a given set of fixed parameters (assuming also a comparable screening factor of the neutron star magnetic field by the currents induced on the disk surface) the revised magnetically threaded disk model predicts a magnetospheric radius that is significantly smaller than that derived from the Ghosh & Lamb (1979) treatment. For a fixed value of the neutron star magnetic field and a wide range of mass accretion rates, the inclusion of a large inclination angle between the neutron star rotation and magnetic field axes (χ ≳ 60 deg) leads to a further decrease of the magnetospheric radius. To illustrate the relevance of these calculations, we consider, as an example, the case of the transitional pulsars. During the so-called high mode of their sub-luminous accretion disk state, these sources have shown X-ray pulsations interpreted as due to accretion at an unprecedented low luminosity level compared to other neutron stars in X-ray binaries. In the context of the magnetic threaded disk model, we show that accretion at luminosities of ∼1033 erg s−1 (and thus accretion-driven X-ray pulsations) can be more easily explained when the prescription of the magnetospheric radius provided by Wang (1997) is used. This avoids the need to invoke very strong propeller outflows in the transitional pulsars, as proposed in other literature works.