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51.
Samir A. Ahmed 《Journal of forecasting》1989,8(1):19-32
An operational filter of traffic state variables is presented for use in designing computer-aided traffic surveillance and control systems. A total of 166 data sets from three traffic surveillance systems were used in the filter development. All the data sets were best represented by an ARIMA (0,1,3) filter. This filter has the following advantages: (1) it yields minimum mean-square-error forecasts if stationarity of the observations can be obtained; (2) it provides much better results than the existing ad hoc filters; (3) it is computationally tractable; and (4) it requires modest computer storage of data. Suggestions and implications for the use of this filter are given. 相似文献
52.
53.
SAP is required for generating long-term humoral immunity 总被引:21,自引:0,他引:21
Long-lived plasma cells and memory B cells are the primary cellular components of long-term humoral immunity and as such are vitally important for the protection afforded by most vaccines. The SAP gene has been identified as the genetic locus responsible for X-linked lymphoproliferative disease, a fatal immunodeficiency. Mutations in SAP have also been identified in some cases of severe common variable immunodeficiency disease. The underlying cellular basis of this genetic disorder remains unclear. We have used a SAP knockout mouse model system to explore the role of SAP in immune responses. Here we report that mice lacking expression of SAP generate strong acute IgG antibody responses after viral infection, but show a near complete absence of virus-specific long-lived plasma cells and memory B cells, despite the presence of virus-specific memory CD4+ T cells. Adoptive transfer experiments show that SAP-deficient B cells are normal and the defect is in CD4+ T cells. Thus, SAP has a crucial role in CD4+ T-cell function: it is essential for late B-cell help and the development of long-term humoral immunity but is not required for early B-cell help and class switching. 相似文献
54.
Over the past decade, there has been a paradigm shift leading consumers and enterprises to the adoption of cloud computing services. Even though most cases are still in the early stages of transition, there has been a steady increase in the implementation of the pay-as-you-go or pay-as-you-grow models offered by cloud providers. Whether applied as an extension of virtual infrastructure, software, or platform as a service, many users are still challenged by the estimation of adequate resource allocation and the wide variations in pricing. Customers require a simple method of predicting future demand in terms of the number of nodes to be allocated in the cloud environment. In this paper, we review and discuss existing methodologies for estimating the demand for cloud nodes and their corresponding pricing policies. Based on our review, we propose a novel approach using the Hidden Markov Model to estimate the acquisition of cloud nodes. 相似文献
55.
Ahmed G 《Discovery and innovation》1994,6(3):291-299
"Though the concept of negotiated settlements gained its momentum in southern Africa--Angola, Mozambique, Namibia and South Africa--the full success of negotiations is yet to be seen in most of these countries.... Demographic consequences of conflicts are explained through a systemic model. The importance of demographic variables on negotiated settlement has also been explained the same way. There is no easy way out to overcome conflicts...but it is suggested that mutual consultation with opposition parties or minorities, or the suppressed people, would help ease many situations in Africa or elsewhere." 相似文献
56.
57.
Ahmed Mostafa Soliman Neveen Samy Gadallah Michael Ohl Hathal Mohammed Al Dhafer 《Journal of Natural History》2017,51(33-34):2057-2085
The apoid wasps of the families Ampulicidae and Heterogynaidae of Saudi Arabia are revised. In Ampulicidae, four species in three genera are reported, of which three species are recorded for the first time from Saudi Arabia (Al-Baha, Asir and Riyadh regions): Ampulex assimilis Kohl, Dolichurus arabicus Ohl and Trirogma caerulea Westwood. Additionally, the family Heterogynaidae is reported for the first time from Saudi Arabia (Asir and Riyadh regions), and a new species, Heterogyna saudita sp. nov., is described, diagnosed and illustrated. An illustrated key to the species of Heterogyna from the Arabian Peninsula is provided.
www.zoobank.org/urn:lsid:zoobank.org:pub:C23C70A7-AA1C-47C0-951A-D164E7B20001 相似文献
58.
M. Mashkour M. Rahimnej S.M. Pourali H. Ezoji Ahmed ElMekawy Deepak Pant 《自然科学进展(英文版)》2017,27(6):647-651
Finite resources of the world''s fossil fuel give rise to the irresistible urge to explore alternative renewable energy
routes such as microbial fuel cells (MFCs). The limited productivity is one of the main obstacles for MFC scalability.
In this study, a dual-chamber MFC was assembled and equipped with fabricated modified cathodes with
titanium dioxide (TiO2) or hybrid graphene (HG) which mainly improved the catalytic activity of the cathode.
The graphite paste (GP) bare electrode was modified by both nanomaterials using a green and facile technique.
The results showed that the modified cathodes resulted in a considerable improvement for the MFC performance,
i.e., the power density reaching levels of 80 mW/m2 for GP-TiO2 and 220 mW/m2 for GP-HG compared to
30 mW/m2 for GP electrode. Additionally, the modified electrodes exhibited lower charge transfer resistance
(Rct) compared to the bare electrode. Therefore, these modified electrodes, fabricated by an eco-friendly method,
could be used as alternatives to the precious expensive metals like Pt. 相似文献
59.
Zusammenfassung In Gegenwart des exfolierten Tonminerals Vermikulit wird die Zitronensäurebildung durchAspergillus niger besonders stimuliert. Dabei wird die Induktionsphase verkürzt sowie die gesamte Gärgeschwindigkeit im messbaren Bereich der Zitronensäurebildungsphase erhöht. Die Stimulierung scheint einzig auf verbesserten Haushalt der Spurenelemente zurückzuführen zu sein. 相似文献
60.
AHMED S.I.-U. 《科学通报(英文版)》2009,54(10):1648-1654
Some insects and animals, such as bugs, grasshoppers and tree frogs, realize their efficient adhesion mechanism to glass surface,
wall and ceiling by injecting a wetting liquid thin film into the pad-substrate contact area. Their ability to control adhesion
(attaching or detaching from a surface) is in many cases connected to the contact geometry and surface patterns of their attachment
pads. This paper focuses on the dependence of the capillary adhesion (wet adhesion) on the micro patterns of the bio-adhesive
pads. The objective is to reveal the possible mechanism for a bio-adhesive pad to control capillary force through adjusting
its micro-scale surface pattern and topography. A capillary adhesion force model is built up taking account of the combined
role of micro-dimple geometry as well as the wetting behavior of the confined liquid thin film. Calculated results of the
apparent contact angle on the regularly micro-dimpled surfaces are compared with and in good agreement with the experimental
measurements. Simulation of the capillary adhesion force reveals that it is controllable in a large magnitude by adjusting
a dimensionless surface pattern parameter k defined as a/(a+b), where a is the diameter of micro dimple, and (a+b) is the side length of one pattern cell. When adjusting the parameter k more than 0.75, the capillary adhesion force could
be switchable from attractive to repulsive. This effect of micro patterns on the interfacial capillary force is proved to
be dominant when the pad-substrate clearance decreases to the nano/micrometer scale. These results indicate that a controllable
and switchable capillary adhesive mechanism might be utilized by a living insect or animal to realize its stable adhesion
and quick releasing movement through adjusting the micro-pattern topography of its bio-adhesive pad.
Supported by the National Natural Science Foundation of China (Grant Nos. 50575123, 50730007), PPP Project from CSC and DAAD,
and German Research Foundation (DFG) (Grant No. SFB622) (Y.H. Liu and S.I.-U. Ahmed) 相似文献