Alternating Hierarchies for Time-Space Tradeoffs

Nepomnjascii's Theorem states that for all 0 0 the class of languages recognized in nondeterministic time n^k and space n^\epsilon, NTISP[n^k, n^\epsilon ], is contained in the linear time hierarchy. By considering restrictions on the size of the universal quantifiers in the linear time hierarchy, this paper refines Nepomnjascii's result to give a sub- hierarchy, Eu-LinH, of the linear time hierarchy that is contained in NP and which contains NTISP[n^k, n^\epsilon ]. Hence, Eu-LinH contains NL and SC. This paper investigates basic structural properties of Eu-LinH. Then the relationships between Eu-LinH and the classes NL, SC, and NP are considered to see if they can shed light on the NL = NP or SC = NP questions. Finally, a new hierarchy, zeta -LinH, is defined to reduce the space requirements needed for the upper bound on Eu-LinH.Comment: 14 page

Semantic Description, Publication and Discovery of Workflows in myGrid

The bioinformatics scientific process relies on in silico experiments, which are experiments executed in full in a computational environment. Scientists wish to encode the designs of these experiments as workflows because they provide minimal, declarative descriptions of the designs, overcoming many barriers to the sharing and re-use of these designs between scientists and enable the use of the most appropriate services available at any one time. We anticipate that the number of workflows will increase quickly as more scientists begin to make use of existing workflow construction tools to express their experiment designs. Discovery then becomes an increasingly hard problem, as it becomes more difficult for a scientist to identify the workflows relevant to their particular research goals amongst all those on offer. While many approaches exist for the publishing and discovery of services, there have been few attempts to address where and how authors of experimental designs should advertise the availability of their work or how relevant workflows can be discovered with minimal effort from the user. As the users designing and adapting experiments will not necessarily have a computer science background, we also have to consider how publishing and discovery can be achieved in such a way that they are not required to have detailed technical knowledge of workflow scripting languages. Furthermore, we believe they should be able to make use of others' expert knowledge (the semantics) of the given scientific domain. In this paper, we define the issues related to the semantic description, publishing and discovery of workflows, and demonstrate how the architecture created by the myGrid project aids scientists in this process. We give a walk-through of how users can construct, publish, annotate, discover and enact workflows via the user interfaces of the myGrid architecture; we then describe novel middleware protocols, making use of the Semantic Web technologies RDF and OWL to support workflow publishing and discovery

Stream-based Translation Models for Statistical Machine Translation

Typical statistical machine translation systems are trained with static parallel corpora. Here we account for scenarios with a continuous incoming stream of parallel training data. Such scenarios include daily governmental proceedings, sustained output from translation agencies, or crowd-sourced translations. We show incorporating recent sentence pairs from the stream improves performance compared with a static baseline. Since frequent batch retraining is computationally demanding we introduce a fast incremental alternative using an online version of the EM algorithm. To bound our memory requirements we use a novel data-structure and associated training regime. When compared to frequent batch retraining, our online time and space-bounded model achieves the same performance with significantly less computational overhead.

HSV-1 ICP0: paving the way for viral replication

Herpes simplex virus type 1 (HSV-1) has two distinct phases of its viral life cycle: lytic and latent. One viral immediate-early protein that is responsible for determining the balance between productive lytic replication and reactivation from latency is infected cell protein 0 (ICP0). ICP0 is a 775-amino acid really interesting new gene (RING)-finger-containing protein that possesses E3 ubiquitin ligase activity, which is required for ICP0 to activate HSV-1 gene expression, disrupt nuclear domain (ND) 10 structures, mediate the degradation of cellular proteins, and evade the host cell’s intrinsic and innate antiviral defenses. This article examines our current understanding of ICP0’s transactivating, E3 ubiquitin ligase, and antihost defense activities and their inter-relationships to one another. Lastly, we will discuss how these properties of ICP0 may be utilized as possible targets for HSV-1 antiviral therapies

The individual as the key-stakeholder of Next Generation Infrastructure: Defining the social value of transport infrastructure in the United Kingdom

The idea of social value has arisen from the psychological approach, and more specifically it is based on the principle of “independence of irrelevant alternatives” from the game theory introduced by Luce and Raiffa1. According to this, each alternative situation has an utility/value for the individual, which is a function of the features of the alternative situation and of the features of the individual who makes the choice. Beyond that, it assumed that the individual, who makes the choice, has a clear and measurable knowledge of the value, which each choice provides. Although even after the evaluation of each choice, it is a tentative situation regarding the choice of the individual. In other words, there is an element of possibility. Under the same principle of Luce and Raiffa, the possibility of a choice is in direct ratio to its value. The above mentioned assumptions constitute the “strict utility choice mode”. The exponential form of the value function is achieved by simple transformations of the “strict utility choice mode”,where X and S have a linear correlation. The exponential functions of the total value have a sigmoid form relative to the linear function of the value of the possible choice. This means that the exponential function may have a sigmoid form relative to the X-axis or Y-axis, based on the defined axes and values. The key challenge addressed is a quantitative sense of value, when the perceptions of value are qualitative. To measure social value quantitatively is challenging, since it is observed that pricing systems are “not based primarily on the users’ identity or activity”, but on the ability and willingness of the final user to pay. The social value gained by the individual is difficult to calculate, since it is defined by human behaviour and human needs. According to Maslow's Hierarchy of Needs, these needs belong to specific groups with specific hierarchy. Maslow developed value (utility) curves of each category of need relative to the age of the individual. The sum of the curves gives an almost sigmoid curve. Winters et al. created a Transportation Hierarchy of Needs and they found the following transport hierarchy of needs: [1] safety and security, [2] time, [3] societal acceptance, [4] cost and [5] comfort and convenience. This research studied value as something holistically affected by all the above factors (time, cost, comfort and convenience, safety and security), without considering their ranking, by asking individuals representative of the UK’s demography to evaluate the social value of eight transport modes (walking, cycling, rail, bus, car, taxi, water and air) and each factor for each mode with a questionnaire survey. The hypothesis tested is that the value to the individual, collectively, from the aforementioned factors should have an almost sigmoid curve, which was verified