39,023 research outputs found
Mathematical models of avascular cancer
This review will outline a number of illustrative mathematical models describing the growth of avascular tumours. The aim of the review is to provide a relatively comprehensive list of existing models in this area and discuss several representative models in greater detail. In the latter part of the review, some possible future avenues of mathematical modelling of avascular tumour development are outlined together with a list of key questions
On the dynamics of a class of multi-group models for vector-borne diseases
The resurgence of vector-borne diseases is an increasing public health
concern, and there is a need for a better understanding of their dynamics. For
a number of diseases, e.g. dengue and chikungunya, this resurgence occurs
mostly in urban environments, which are naturally very heterogeneous,
particularly due to population circulation. In this scenario, there is an
increasing interest in both multi-patch and multi-group models for such
diseases. In this work, we study the dynamics of a vector borne disease within
a class of multi-group models that extends the classical Bailey-Dietz model.
This class includes many of the proposed models in the literature, and it can
accommodate various functional forms of the infection force. For such models,
the vector-host/host-vector contact network topology gives rise to a bipartite
graph which has different properties from the ones usually found in directly
transmitted diseases. Under the assumption that the contact network is strongly
connected, we can define the basic reproductive number and show
that this system has only two equilibria: the so called disease free
equilibrium (DFE); and a unique interior equilibrium---usually termed the
endemic equilibrium (EE)---that exists if, and only if, . We
also show that, if , then the DFE equilibrium is globally
asymptotically stable, while when , we have that the EE is
globally asymptotically stable
The ever-evolving concept of the gene: The use of RNA/Protein experimental techniques to understand genome functions
The completion of the human genome sequence together with advances in sequencing technologies have shifted the paradigm of the genome, as composed of discrete and hereditable coding entities, and have shown the abundance of functional noncoding DNA. This part of the genome, previously dismissed as "junk" DNA, increases proportionally with organismal complexity and contributes to gene regulation beyond the boundaries of known protein-coding genes. Different classes of functionally relevant nonprotein-coding RNAs are transcribed from noncoding DNA sequences. Among them are the long noncoding RNAs (lncRNAs), which are thought to participate in the basal regulation of protein-coding genes at both transcriptional and post-transcriptional levels. Although knowledge of this field is still limited, the ability of lncRNAs to localize in different cellular compartments, to fold into specific secondary structures and to interact with different molecules (RNA or proteins) endows them with multiple regulatory mechanisms. It is becoming evident that lncRNAs may play a crucial role in most biological processes such as the control of development, differentiation and cell growth. This review places the evolution of the concept of the gene in its historical context, from Darwin's hypothetical mechanism of heredity to the post-genomic era. We discuss how the original idea of protein-coding genes as unique determinants of phenotypic traits has been reconsidered in light of the existence of noncoding RNAs. We summarize the technological developments which have been made in the genome-wide identification and study of lncRNAs and emphasize the methodologies that have aided our understanding of the complexity of lncRNA-protein interactions in recent years
Recommended from our members
Biological fieldwork provision in higher education
Fieldwork is regarded as an important component of many bioscience degree programmes. QAA benchmarks statements refer explicitly to the importance of fieldwork, although give no indication of amounts of field provision expected. Previous research has highlighted the importance of fieldwork to the learning of both subject-specific and transferable skills. However, it is unclear how the amount and type of fieldwork currently offered is being affected by the recent expansion in student numbers and current funding constraints. Here we review contemporary literature and report on the results of a questionnaire completed by bioscience tutors across 33 UK institutions. The results suggest, perhaps contrary to anecdotal evidence, that the amount of fieldwork being undertaken by students is not in decline and that on the whole, programmes contain reasonable amounts of fieldwork. The majority of programmes involved UK-based fieldwork, but a number of programmes also offered ‘exotic’ overseas fieldwork which was considered important in terms of student recruitment as well as exposing students to a diversity of field learning environments. Tutors were very clear about the benefits of fieldwork and the need to be proactive to maintain its provision
- …