Genetic instability in radiation-induced leukaemias: mouse models

Ivermectin is not lethal to the adult worms of Onchocerca volvulus or to those of O. ochengi, a cattle parasite closely related to O. volvulus. Although ivermectin penetrates the nodules in which the adults of these nematodes live, it is not known what levels of the drug enter the worms. Adult male O. ochengi were incubated in [3H]ivermectin in a saturated solution of unlabelled ivermectin (11.44 microM), to measure uptake by the oral and transcuticular routes, and in [3H]inulin, to ascertain if oral ingestion occurs in vitro. Uptake of [3H]ivermectin was high [1040 disintegrations/min (d.p.m.) at 3 h, representing a mean total of 86 pmoles ivermectin/worm] and occurred predominantly by the transcuticular route. Viability of worms was not reduced by this exposure, and uptake continued for up to 12 h. Only low levels of [3H]inulin (four d.p.m.) were detected in worms, indicating that the gut is probably not functional in vitro. Scanning and transmission electron microscopy revealed that the epicuticle of both sexes had an irregular surface which was pitted with a honeycomb structure in males, and rough and abundantly folded in females. These structures greatly increased the absorptive surface of the worms. In conclusion, ivermectin is able to enter adult O. ochengi males at concentrations sufficient to kill non-filarial nematodes.     

Spectroelectrochemical sensing based on attenuated total internal reflectance stripping voltammetry. 2. Determination of mercury and lead

Detection of lead and mercury by attenuated total internal reflectance spectroscopy coupled to stripping voltammetry is demonstrated. Changes in attenuation of light passing through an indium tin oxide optically transparent electrode (ITO-OTE) accompany the electrodeposition and stripping of lead and mercury on the electrode surface. The change in absorbance during stripping of electrodeposited metal constitutes the analytical response that enables detection over a range of 2.5 x 10(-7)-5 x 10(-5) and 5 x 10(-8)-5 x 10(-5) M for mercury and lead, respectively. The spectroelectrochemical responses of mercury and lead on the ITO surface are characterized and optimized with respect to solution conditions, the potential excitation signals used for deposition and stripping, and wavelength for detection. The deposited metals were examined by environmental scanning electron miscroscopy, and the electrodeposition pattern of lead and mercury was found to influence the optical response.     

Outbound authentication for programmable secure coprocessors

A programmable secure coprocessor platform can help solve many security problems in distributed computing, particularly if coprocessor applications can participate as full-fledged parties in distributed cryptographic protocols. Thus, a generic platform must not only provide programmability, maintenance, and configuration in the hostile field, it must also provide outbound authentication for the entities that result. This paper offers our experiences in solving this problem for a high-end secure coprocessor product. This work required synthesis of a number of techniques, so that parties with different and dynamic views of trust can draw sound and complete conclusions about remote coprocessor applications.     

Modification point depth and genome growth in genetic programming

The evolutionary computation community has shown increasing interest in arbitrary-length representations, particularly in the field of genetic programming. A serious stumbling block to the scalability of such representations has been bloat: uncontrolled genome growth during an evolutionary run. Bloat appears across the evolutionary computation spectrum, but genetic programming has given it by far the most attention. Most genetic programming models explain this phenomenon as a result of the growth of introns, areas in an individual which serve no functional purpose. This paper presents evidence which directly contradicts intron theories as applied to tree-based genetic programming. The paper then uses data drawn from this evidence to propose a new model of genome growth. In this model, bloat in genetic programming is a function of the mean depth of the modification (crossover or mutation) point. Points far from the root are correspondingly less likely to hurt the child's survivability in the next generation. The modification point is in turn strongly correlated to average parent tree size and to removed subtree size, both of which are directly linked to the size of the resulting child.     

Network Analysis of Commuting Flows: A Comparative Static Approach to German Data

The analysis of complex networks has recently received considerable attention. The work by Albert and Barabási presented a research challenge to network analysis, that is, growth of the network. The present paper offers a network analysis of the spatial commuting network in Germany. First, we study the spatial evolution of the commuting network over time. Secondly, we compare two spatial interaction model (SIM) specifications, in order to replicate the actual network structure. Our findings suggest that the commuting network appeared to become more dense and clustered, while the SIMs seem to require more sophisticated specifications, in order to replicate such a connectivity structure.     

Effects of 42 hr of total sleep deprivation on component processes of verbal working memory.

The current investigation examined changes in working memory (WM) component processes following total sleep deprivation (TSD) in a sample of healthy young persons. Forty subjects were administered a verbal form of a continuous recognition test (CRT) before and after 42 hr of TSD. Parameters of a computational model of the CRT reflecting attention, WM span, and rate of episodic memory encoding were estimated for each individual. Subjects made more errors on the test following sleep deprivation. Analysis of model parameters revealed statistically independent declines in both the attention and WM span parameters, with a larger effect observed for the decline in WM span. Examination of individual profiles suggested that the effects of TSD on verbal WM component processes vary from person to person. Declines in global verbal WM functioning appear to be primarily driven by reduced WM span and attention; however, these effects may be individual-specific. Further applications of the computational model for examining WM component processes with sleep deprivation and other clinical populations are discussed. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

In Planta Response of Arabidopsis to Photothermal Impact Mediated by Gold Nanoparticles

Biological responses to photothermal effects of gold nanoparticles (GNPs) have been demonstrated and employed for various applications in diverse systems except for one important class – plants. Here, the uptake of GNPs through Arabidopsis thaliana roots and translocation to leaves are reported. Successful plasmonic nanobubble generation and acoustic signal detection in planta is demonstrated. Furthermore, Arabidopsis leaves harboring GNPs and exposed to continuous laser or noncoherent light show elevated temperatures across the leaf surface and induced expression of heat‐shock regulated genes. Overall, these results demonstrate that Arabidopsis can readily take up GNPs through the roots and translocate the particles to leaf tissues. Once within leaves, GNPs can act as photothermal agents for on‐demand remote activation of localized biological processes in plants.     

Contextual web searches in Facebook using learning materials and discussion messages

The web is nowadays one of the main information sources, and information search is an important area in which many advances have been registered. One approach to improve web search results is to consider contextual information. Usually, information about context has been provided through user logs on previous searches or the monitoring of clicks on first results, but different approaches can be used in specific environments. In a web based learning environment, existing documents and exchanged messages could provide contextual information. So, the main goal of this work is to provide a contextual web search engine based on shared documents and messages posted in a social network used for collaborative learning. Contextual search is provided through query expansion using learning documents (material provided by the teacher) and discussion messages (posts, links and comments that result from the participants’ interactions). A prototype was implemented and used in a learning scenario to acquire the context in a learning community. The proposed approach makes the context acquisition faster and more dynamic as it considers an automatic approach over text processing of documents and discussions. In addition, the results of the query engine with and without the contextual information were compared and the proposed approach using contextual information showed improvements in the precision of the results.     

Computational system identification for Bayesian NARMAX modelling

In this contribution we derive a computational Bayesian approach to NARMAX model identification. The identification algorithm exploits continuing advances in computational processing power to numerically obtain posterior distributions for both model structure and parameters via sampling methods. The main advantage of this approach over other NARMAX identification algorithms is that for the first time model uncertainty is characterised as a byproduct of the identification procedure. The algorithm is based on the reversible jump Markov chain Monte Carlo (RJMCMC) procedure. Key features of the approach are (i) sampling of unselected model terms for testing for inclusion in the model (the birth move), which encourages global searching of the model term space, (ii) sampling of previously selected model terms for testing for exclusion from the model—a naturally incorporated pruning step (the death move), which leads to model parsimony, and (iii) estimation of model and parameter distributions, which are naturally generated in the Bayesian framework. We present a numerical example to demonstrate the algorithm and a comparison with a forward regression method: the results show that the RJMCMC approach is competitive and gives useful additional information regarding uncertainty in both model parameters and structure.     

The stability of preferences for life-sustaining care among persons with AIDS in the Boston Health Study

In 1982, the World Health Organization (WHO) identified inadequate relief from cancer pain as an international health problem. WHO recommended that governments develop and implement national policies and programs for cancer pain relief. This report evaluates national health policy and the systems of health care delivery in relation to cancer pain management in the new South Africa. This field study included multiple methods of data collection: analysis of documents, field trips with participant observation in sites of care delivery, focused interviews, and in-depth interviews of key informants. The purposive sample of key informants (n = 33) represented multiple stakeholders in a variety of settings. Strengths of the developing health policy include specific recommendations related to palliative care; the shift to universal primary care; policies to support drug availability; the inclusion of morphine and codeine as essential drug at the primary health care level; and the development of a national standard related to cancer pain management. Health services are characterized by two parallel systems of care (private and public) with numerous vestiges of the inequities of apartheid. The management of pain varies by provider and setting; major problems with access exist in the rural areas. Health services in South Africa have been plagued by inequity and inadequate resources. New health policies have set a path to ensure universal access to health care including palliative care for cancer. Their successful implementation is the next necessary step toward improving health services and alleviating the suffering of increasing numbers of individuals with cancer.