共查询到20条相似文献,搜索用时 15 毫秒
1.
The present communication is an attempt to describe the mode of propagation of AIDS epidemic and its control programme using a branching process as well as a birth-death and immigration model. A comparison of the project of AIDS control programme on the basis of its propagation by a continuous branching process model with that of a linear birth and death process with immigration shows a remarkable contrast. Branching process model shows that it is possible to control the propagation of the disease by suitably increasing the detection rate and lowering the infection rate. However, the propagation of AIDS models by birth and death Process with or without immigration shows that it is increasingly difficult to control the invasion of AIDS merely by controlling the birth, death and immigration parameters. 相似文献
2.
The French and Japanese Developmental Biology Societies, teaming up with Human Frontier Science Program, were eager to meet back in person in November 2022 in the lovely city of Strasbourg. Top scientists in the developmental biology field from France and Japan, but also from United States, United Kingdom, Switzerland or Germany shared their exciting science during the 4 days of this meeting. Core fields of developmental biology such as morphogenesis, patterning, cell identity, and cell state transition, notably at the single cell level, were well represented, and a diversity of experimental models, including plants, animals, and other exotic organisms, as well as some in vitro cellular models, were covered. This event also extended the scope of classic scientific gatherings for two reasons. First the involvement of artists during the preparation of the event and on site. Second, part of the meeting was open for the general public through a series of outreach events, including a music and video presentation through projection mapping at Rohan palace, as well as public lectures. 相似文献
3.
4.
5.
6.
Chia-Tsung Horng Wen-Jang Huang Mong-Na Lo Huang 《Biometrical journal. Biometrische Zeitschrift》1990,32(8):985-1004
In a single compartment quantal response model, besides the input and release processes, an inspection process, assumed to be independent of the input and release processes, is considered. Each time when a release occurs, we assume the amount of release is randomly proportional to the amount present and the proportional rates form a sequence of independent and identically distributed random variables with support on [0, 1]. The input policy we consider is a modification of (s, S) input policy in the inventory model. More precisely, let 0 ≦s2 ≦s1 ≦s ≦ S, if after a release, the amount of the drug in subject's body is less than a level s2 which is small enough, then there will be an input immediately with probability 1 — p and no more inputs thereafter with probability p, also there will be an input immediately if the dose level is in the interval [s2, s1). If the dose level is in the interval [s1, s) there will be no input unless the inspector arrives. On the other hand, if the dose level is greater than or equal to s, then there will be no input. We consider a stochastic model as described above, and obtain the expressions for some quantities of interest. A Monte Carlo study has also been carried out to demonstrate some behaviors of our quantal response process. 相似文献
7.
Inference for gamma and stable processes 总被引:2,自引:0,他引:2
8.
Charles F. Goochee 《Cytotechnology》2002,38(1-3):63-76
The transfer of processes for biotherapeutic products into finalmanufacturing facilities was frequently problematic during the 1980's and early 1990's, resulting in costly delays to licensure(Pisano 1997). While plant startups for this class of products can become chaotic affairs, this is not an inherent or intrinsic feature. Major classes of process startup problems have been identified andmechanisms have been developed to reduce their likelihood of occurrence. These classes of process startup problems and resolution mechanisms are the major topic of this article. With proper planning and sufficient staffing, the probably of a smooth process startup for a biopharmaceutical product can be very high – i.e., successful process performance will often beachieved within the first two full-scale process lots in the plant. The primary focus of this article is the role of the Process Development Group in helping to assure this high probability of success. 相似文献
9.
10.
Vivek Rangarajan 《Biotechnology & genetic engineering reviews》2015,31(1-2):46-68
The growing interest in Bacillus lipopeptides for high-value applications has driven process design, development and optimization for enhanced lipopeptide production. Traditional optimization approaches have been directed towards improving the overall titres by modification of media components and environmental parameters, almost exclusively in submerged cultures. Carbon and nitrogen sources, trace elements and oxygen availability have all been demonstrated to exhibit significant influences on lipopeptide yield, productivity and selectivity. This insight into process-linked kinetics, especially selectivity, has led to the introduction of novel process intensification and integration strategies which further promote process efficiency, and which include foam fractionation, inverse fluidization, rotating disc contacting and microfiltration with recycle. These strategies have not only transformed the production capabilities, but have also successfully integrated upstream production with downstream purification through cell retention and in situ product removal. This review analyses and critically discusses the impact of process conditions and process optimization strategies for improving lipopeptide production kinetics, specifically highlighting the emerging trend of process intensification and integration strategies and further, proposes a heuristic route to enhance lipopeptide production. 相似文献
11.
12.
13.
14.
15.
Data obtained from quantifying the upper part of the mandibular ramus (the coronoid process, the condylar process, and the notch between them) lead us to conclude that Neanderthals (both European and Middle Eastern) differ more from Homo sapiens (early specimens such as Tabun II, Skhul, and Qafzeh, as well as contemporary populations from as far apart as Alaska and Australia) than the latter differs from Homo erectus. The specialized Neanderthal mandibular ramus morphology emerges as yet another element constituting the derived complex of morphologies of the mandible and face that are unique to Neanderthals. These morphologies provide further support for the contention that Neanderthals do not play a role in modern human biological ancestry, either through "regional continuity" or through any other form of anagenetic progression. 相似文献
16.
17.
Sani I. Doguwa 《Biometrical journal. Biometrische Zeitschrift》1989,31(4):451-459
Getis and Franklin (1987), introduced a technique based on second order methods, called second order neighbourhood method, which is used to quantify clustering at various spatial scales. Variants of this method are introduced for testing whether a spatial point pattern is consistent with the hypothesis of a Poisson process. These variants are applied to point location data for a sample of Ponderosa pine (Pinus ponderosa) trees. 相似文献
18.
19.
Mili Pathak Prashant Pokhriyal Irshad Gandhi Sridevi Khambhampaty 《Biotechnology progress》2022,38(3):e3252
Process understanding and characterization forms the foundation, ensuring consistent and robust biologics manufacturing process. Using appropriate modeling tools and machine learning approaches, the process data can be monitored in real time to avoid manufacturing risks. In this article, we have outlined an approach toward implementation of chemometrics and machine learning tools (neural network analysis) to model and predict the behavior of a mixed-mode chromatography step for a biosimilar (Teriparatide) as a case study. The process development data and process knowledge was assimilated into a prior process knowledge assessment using chemometrics tools to derive important parameters critical to performance indicators (i.e., potential quality and process attributes) and to establish the severity ranking for the FMEA analysis. The characterization data of the chromatographic operation are presented alongwith the determination of the critical, key and non- key process parameters, set points, operating, process acceptance and characterized ranges. The scale-down model establishment was assessed using traditional approaches and novel approaches like batch evolution model and neural network analysis. The batch evolution model was further used to demonstrate batch monitoring through direct chromatographic data, thus demonstrating its application for continuos process verification. Assimilation of process knowledge through a structured data acquisition approach, built-in from process development to continuous process verification was demonstrated to result in a data analytics driven model that can be coupled with machine learning tools for real time process monitoring. We recommend application of these approaches with the FDA guidance on stage wise process development and validation to reduce manufacturing risks. 相似文献
20.
Gernhard T 《Journal of theoretical biology》2008,253(4):769-778
We investigate a neutral model for speciation and extinction, the constant rate birth-death process. The process is conditioned to have n extant species today, we look at the tree distribution of the reconstructed trees—i.e. the trees without the extinct species. Whereas the tree shape distribution is well-known and actually the same as under the pure birth process, no analytic results for the speciation times were known. We provide the distribution for the speciation times and calculate the expectations analytically. This characterizes the reconstructed trees completely. We will show how the results can be used to date phylogenies. 相似文献