1,440 research outputs found
Dominant Superconducting Fluctuations in the One-Dimensional Extended Holstein-Extended Hubbard model
The search for realistic one-dimensional (1D) models that exhibit dominant
superconducting (SC) fluctuations effects has a long history. In these 1D
systems, the effects of commensurate band fillings--strongest at
half-filling--and electronic repulsions typically lead to a finite charge gap
and the favoring of insulating density wave ordering over superconductivity.
Accordingly, recent proposals suggesting a gapless metallic state in the
Holstein-Hubbard (HH) model, possibly superconducting, have generated
considerable interest and controversy, with the most recent work demonstrating
that the putative dominant superconducting state likely does not exist. In this
paper we study a model with non-local electron-phonon interactions, in addition
to electron-electron interactions, this model unambiguously possesses dominant
superconducting fluctuations at half filling in a large region of parameter
space. Using both the numerical multi-scale functional renormalization group
for the full model and an analytic conventional renormalization group for a
bosonized version of the model, we demonstrate the existence of dominant
superconducting (SC) fluctuations. These dominant SC fluctuations arise because
the spin-charge coupling at high energy is weakened by the non-local
electron-phonon interaction and the charge gap is destroyed by the resultant
suppression of the Umklapp process. The existence of the dominant SC pairing
instability in this half-filled 1D system suggests that non-local
boson-mediated interactions may be important in the superconductivity observed
in the organic superconductors.Comment: 8 pages, 4 figure
Functional renormalization group analysis of the half-filled one-dimensional extended Hubbard model
We study the phase diagram of the half-filled one-dimensional extended Hubbard model at weak coupling using a novel functional renormalization group (FRG) approach. The FRG method includes in a systematic manner the effects of the scattering processes involving electrons away from the Fermi points. Our results confirm the existence of a finite region of bond charge density wave, also known as a "bond order wave" near U=2V and clarify why earlier g-ology calculations have not found this phase. We argue that this is an example in which formally irrelevant corrections change the topology of the phase diagram. Whenever marginal terms lead to an accidental symmetry, this generalized FRG method may be crucial to characterize the phase diagram accurately.First author draf
The Association between Traditional Chinese Dietary and Herbal Therapies and Uterine Involution in Postpartum Women
Background. Traditional Chinese postpartum care is believed to help in the recovery of women after delivery. Objective. This study investigated the association of elements in dietary and herbal therapy with uterine involution. Methods. Indices of uterine involution were measured ultrasonographically in 127 postpartum women between 4-6 weeks after delivery. A self-reported retrospective questionnaire was used to query women about their frequencies of taking herbal medicines and consuming special diets during the first month after delivery. Correlation coefficients were calculated to identify the associations, then the regression models were used to identify the predictors. Result. Among the herbal medicines and diet, consumption of Eucommia ulmoides (E. ulmoides) negatively correlated with the AP diameter of the uterus and the cavity. E. ulmoides was also the only predictor of maximum AP diameter of the uterus, AP diameter of the uterus 5 cm from the fundus, and the maximum AP diameter of the cavity. Moreover, consumption of Sheng-hau-tang was significantly correlated with anteverted uterus and was a predictor of anteverted uterus. Conclusion. E. ulmoides and Sheng-hau-tang positively correlated with the degree of uterine involution after delivery, implying that both therapies might possess the pharmacological efficacy of uterine contraction in postpartum women
The Interrelationships of Managing Knowledge and Organizational Learning: A Case Study of a British Retailer
Customer data collected from business transactions have long been used in the retailing industry as a basis for analysing company performance and consumer behaviour. However, despite the widespread recognition of the value of customer data for retailers, relatively few studies have examined the process by which data are transformed into information and organisational knowledge. Such transformation is considered as part of organizational learning. Even fewer studies have considered the dynamics of cross-functional knowledge sharing and integration within the retailing sector. To fill this gap, this research-inprogress looks at one of the Britain’s largest retailers, Boots the Chemist (BTC), transforms its customer data into knowledge via organizational learning. The likely contribution to the literature is like such attempt could be considered as the first step towards linking up the growing division of organizational learning and knowledge management studies. The purpose of the research is to examine how customer data collected from business transactions were used as the foundation for generating strategically valuable information and knowledge, and how knowledge was shared and integrated across business functions. Several important issues are to be highlighted in the study, in particular: (1) the transformation of data, information and knowledge via organizational learning; (2) the integration of departmental knowledge and the creation of new organisational knowledge; (3) knowledge sharing as a socio-technical phenomenon. The case illustrates the importance of developing and maintaining interdepartmental relationships as a means of sharing and integrating strategically valuable knowledge
Sequential change in olfaction and (non) motor symptoms: the difference between anosmia and non-anosmia in Parkinson’s disease
IntroductionHyposmia is a common prodrome in patients with Parkinson’s disease (PD). This study investigates whether olfactory changes in PD differ according to the degree of olfactory dysfunction and whether there are changes in motor and non-motor symptoms.MethodsThe 129 subjects with PD were divided into two groups: anosmia and non-anosmia. All cases were reassessed within 1–3 years after the initial assessment. The assessment included the MDS-Unified PD Rating Scale (MDS-UPDRS), the University of Pennsylvania Smell Identification Test (UPSIT), Beck’s Depression Inventory-II (BDI-II), Montreal Cognitive Assessment (MoCA), and equivalence dose of daily levodopa (LEDD). The generalized estimating equation (GEE) model with an exchangeable correlation structure was used to analyze the change in baseline and follow-up tracking and the disparity in change between these two groups.ResultsThe anosmia group was older and had a longer disease duration than the non-anosmia group. There was a significant decrease in UPSIT after follow-up in the non-anosmia group (β = −3.62, p < 0.001) and a significant difference in the change between the two groups (group-by-time effect, β = 4.03, p < 0.001). In the third part of the UPDRS motor scores, there was a tendency to increase the score in the non-anosmia group compared to the anosmia group (group-by-time effect, β = −4.2, p < 0.038). There was no significant difference in the group-by-time effect for UPDRS total score, LEDD, BDI-II, and MoCA scores.DiscussionIn conclusion, this study found that olfactory sensation may still regress in PD with a shorter disease course without anosmia, but it remains stable in the anosmia group. Such a decline in olfaction may not be related to cognitive status but may be associated with motor progression
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