4,271 research outputs found
Reactive dynamics on fractal sets: anomalous fluctuations and memory effects
We study the effect of fractal initial conditions in closed reactive systems
in the cases of both mobile and immobile reactants. For the reaction , in the absence of diffusion, the mean number of particles is shown to
decay exponentially to a steady state which depends on the details of the
initial conditions. The nature of this dependence is demonstrated both
analytically and numerically. In contrast, when diffusion is incorporated, it
is shown that the mean number of particles decays asymptotically as
, the memory of the initial conditions being now carried by the
dynamical power law exponent. The latter is fully determined by the fractal
dimension of the initial conditions.Comment: 7 pages, 2 figures, uses epl.cl
A study on the concepts and themes of color and light in the exquisite islamic architecture
Today, diverse ideologies, thoughts, and beliefs exist in the world all of which try to transfer concepts and ideas to others using the indirect language of semantics. In this regard, architecture, especially the valuable architecture of Iran with wide application and permanent presence in human life has gained considerable attention. Iranian art has always been in coordination with the spirit of Islam and an indicator of its truth. Architecture is where meaning is represented in the formal, structural, and spatial aspects. Light and color are two important visual elements of formation and cognition of architectural works. Color does not manifest by itself unless it is seen through a design, when becomes the origin of work and intervenes in its sense of space.It should be considered that how the existence of light and color in the patterns has been effective in the environmental psychology and how the space is defined in terms of these two elements? And whether the sole use of light and color in the historical architecture was to represent meaning?The present study adopts a descriptive-analytical approach to review and explain the semantic elements of light and color, their application and conceptual features in the historical architecture and hence examines these two distinct elements in the art and architecture of the past and tries to find their semantic features to the extent that have influenced the face and essence of modern architecture in the hope of providing useful insights for the modern architecture.Keywords: Islamic architecture, light, color, concepts, exquisite architectur
Cyber-physical system based on image recognition to improve traffic flow: A case study
Vehicular traffic in metropolitan areas turns congested along either paths or periods. As a case study, we have considered a mass transport system with a bus fleet that rides over exclusive lanes across streets and avenues in an urban area that does not allow
the circulation of lightweight vehicles, cargo, and motorcycles. This traffic flow becomes congested due to the absence of restriction policies based on criteria. Moreover, the exclusive lanes are at ground level, decreasing lanes for other vehicles. The main objective of this proposal consists of controlling the access to the exclusive lanes by a cyber-physical system following authorization conditions, verifying the permission status of a vehicle by the accurate recognition of license plates to reduce traffic congestion. Therefore, in the case of invading an exclusive lane without permission, the vehicle owner gets a notification of the fine with the respective evidence
Integrable su(3) spin chain combining different representations
The general expression for the local matrix of a quantum chain
with the site space in any representation of su(3) is obtained. This is made by
generalizing from the fundamental representation and imposing the
fulfillment of the Yang-Baxter equation. Then, a non-homogeneous spin chain
combining different representations of su(3) is solved by developing a method
inspired in the nested Bethe ansatz. The solution for the eigenvalues of the
trace of the monodromy matrix is given as two coupled Bethe equations. A
conjecture about the solution of a chain with the site states in different
representations of su(n) is presented. The thermodynamic limit of the ground
state is calculated.Comment: PlainTex harvmac, 30 pages, 7 figures, to appear in Journal of
Physics
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Developing a serocorrelate of protection against invasive group B streptococcus disease in pregnant women: a feasibility study.
BACKGROUND: Group B streptococcus is the leading cause of infection in infants. Currently, intrapartum antibiotic prophylaxis is the major strategy to prevent invasive group B streptococcus disease. However, intrapartum antibiotic prophylaxis does not prevent maternal sepsis, premature births, stillbirths or late-onset disease. Maternal vaccination may offer an alternative strategy. Multivalent polysaccharide protein conjugate vaccine development is under way and a serocorrelate of protection is needed to expedite vaccine licensure. OBJECTIVES: The ultimate aim of this work is to determine the correlate of protection against the major group B streptococcus disease-causing serotypes in infants in the UK. The aim of this feasibility study is to test key operational aspects of the study design. DESIGN: Prospective cohort study of pregnant women and their infants in a 6-month period (1 July to 31 December 2018). SETTING: Five secondary and tertiary hospitals from London and South England. National iGBS disease surveillance was conducted in all trusts in England and Wales. PARTICIPANTS: Pregnant women aged ≥ 18 years who were delivering at one of the selected hospitals and who provided consent during the study period. There were no exclusion criteria. INTERVENTIONS: No interventions were performed. MAIN OUTCOME MEASURES: (1) To test the feasibility of collecting serum at delivery from a large cohort of pregnant women. (2) To test the key operational aspects for a proposed large serocorrelates study. (3) To test the feasibility of collecting samples from those with invasive group B streptococcus. RESULTS: A total of 1823 women were recruited during the study period. Overall, 85% of serum samples were collected at three sites collecting only cord blood. At the two sites collecting maternal, cord and infant blood samples, the collection rate was 60%. A total of 614 women were screened for group B streptococcus with a colonisation rate of 22% (serotype distribution: 30% III, 25% Ia, 16% II, 14% Ib, 14% V and 1% IV). A blood sample was collected from 34 infants who were born to colonised women. Maternal and infant blood and the bacterial isolates for 15 newborns who developed invasive group B streptococcal disease during the study period were collected (serotype distribution: 29% III, 29% II, 21% Ia, 7% Ib, 7% IV and 7% V). LIMITATIONS: Recruitment and sample collection were dependent on the presence of research midwives rather than the whole clinical team. In addition, individualised consent limited the number of women who could be approached each day, and site set-up for the national surveillance study and the limited time period of this feasibility study limited recruitment of all eligible participants. CONCLUSIONS: We have verified the feasibility of collecting and processing rectovaginal swabs and blood samples in pregnant women, as well as samples from those with invasive group B streptococcal disease. We have made recommendations for the recruitment of cases within the proposed GBS3 study and for controls both within GBS3 and as an extension of this feasibility study. FUTURE WORK: A large case-control study comparing specific immunoglobulin G levels in mothers whose infants develop invasive group B streptococcal disease with those in colonised mothers whose infants do not develop invasive group B streptococcal disease is recommended. TRIAL REGISTRATION: Current Controlled Trials ISRCTN49326091; IRAS project identification number 246149/REC reference number 18/WM/0147. FUNDING: This project was funded by the National Institute for Health Research (NIHR) Health Technology Assessment programme and will be published in full in Health Technology Assessment; Vol. 23, No. 67. See the NIHR Journals Library website for further project information
The Effects of Retrogression and Reaging on Aluminum Alloy 2099 (C458)
The objective of this study was to investigate the feasibility of performing retrogression and reaging (RRA) heat treatments on 2099 aluminum-lithium alloy. The retrogression temperatures were 200-250 A degrees C and retrogression times were 5-60 min. Half of the samples were exposed to a salt fog environment. Interestingly, the samples exposed to salt spray had consistently higher mechanical tensile properties than those which were not exposed
The Effects of Retrogression and Reaging on Aluminum Alloy 2195
A retrogression and reaging (RRA) treatment was performed on 2195 Al-Li Alloy. The exposure times were from 5 to 60 min, and the temperatures were from 200 to 250 A degrees C. Samples that were exposed to a salt spray test had overall similar mechanical properties as compared to those that were not exposed. The percent elongation, however, was significantly deteriorated due to the salt spray exposure. The mechanical properties of the 2195 samples were compared to those of 2099 samples exposed to similar treatments in an earlier study
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