Chromatin modifications involved in the DNA damage response to double strand breaks

In eukaryotes, genomic DNA is tightly compacted into a protein-DNA complex known as chromatin. This dense structure presents a barrier to DNA-dependent processes including transcription, replication and DNA repair. The repressive structure of chromatin is overcome by ATP-dependent chromatin remodelling complexes and chromatin-modifying enzymes. There is now ample evidence that DNA double-strand breaks (DSBs) elicit various histone modifications (such as acetylation, deacetylation, and phosphorylation) that function combinatorially to control the dynamic structure of the chromatin microenvironment. The role of these mechanisms during transcription and replication has been well studied, while the research into their impact on regulation of DNA damage response is rapidly gaining momentum. How chromatin structure is remodeled in response to DNA damage and how such alterations influence DSB repair are currently significant questions. This review will summarise the major chromatin modifications and chromatin remodelling complexes implicated in the DNA damage response to DSBs.

Blocking layer optimisation of poly(3-hexylthiopene)based solid state dye sensitized solar cells

The optimisation study of the fabrication of a compact TiO2 blocking layer (via Spray Pyrolysis Deposition) for poly (3-hexylthiopene) (P3HT) for Solid State Dye Sensitized Solar Cells (SDSCs) is reported. We used a novel spray TiO2 precursor solution composition obtained by adding acetylacetone to a conventional formulation (Diisopropoxytitanium bis (acetylacetonate) in ethanol). By Scanning Electron Microscopy a TiO2 layer with compact morphology and thickness of around 100 nmis shown. Through a Tafel plot analysis an enhancement of the device diode-like behaviour induced by the acetylacetone blocking layer respect to the conventional one is observed. Significantly, the device fabricatedwith the acetylacetone blocking layer shows an overall increment of the cell performance with respect to the cellwith the conventional one (DJsc/Jsc = +13.8%, DFF/FF = +39.7%, DPCE/PCE = +55.6%). A conversion efficiency optimumis found for 15 successive spray cycles where the diode-like behaviour of the acetylacetone blocking layer is more effective. Over three batches of cells (fabricated with P3HT and dye D35) an average conversion efficiency value of 3.9% (under a class A sun simulator with 1 sun A.M. 1.5 illumination conditions) was measured. From the best cell we fabricated a conversion efficiency value of 4.5% was extracted. This represents a significant increment with respect to previously reported values for P3HT/dye D35 based SDSCs.

Damage diagnosis for complex steel truss bridges using multi-layer genetic algorithm

Considerate amount of research has proposed optimization-based approaches employing various vibration parameters for structural damage diagnosis. The damage detection by these methods is in fact a result of updating the analytical structural model in line with the current physical model. The feasibility of these approaches has been proven. But most of the verification has been done on simple structures, such as beams or plates. In the application on a complex structure, like steel truss bridges, a traditional optimization process will cost massive computational resources and lengthy convergence. This study presents a multi-layer genetic algorithm (ML-GA) to overcome the problem. Unlike the tedious convergence process in a conventional damage optimization process, in each layer, the proposed algorithm divides the GA’s population into groups with a less number of damage candidates; then, the converged population in each group evolves as an initial population of the next layer, where the groups merge to larger groups. In a damage detection process featuring ML-GA, as parallel computation can be implemented, the optimization performance and computational efficiency can be enhanced. In order to assess the proposed algorithm, the modal strain energy correlation (MSEC) has been considered as the objective function. Several damage scenarios of a complex steel truss bridge’s finite element model have been employed to evaluate the effectiveness and performance of ML-GA, against a conventional GA. In both single- and multiple damage scenarios, the analytical and experimental study shows that the MSEC index has achieved excellent damage indication and efficiency using the proposed ML-GA, whereas the conventional GA only converges at a local solution.

Cross-layer design and optimization for wireless networked control systems

Wireless networked control systems (WNCSs) have been widely used in the areas of manufacturing and industrial processing over the last few years. They provide real-time control with a unique characteristic: periodic traffic. These systems have a time-critical requirement. Due to current wireless mechanisms, the WNCS performance suffers from long time-varying delays, packet dropout, and inefficient channel utilization. Current wirelessly networked applications like WNCSs are designed upon the layered architecture basis. The features of this layered architecture constrain the performance of these demanding applications. Numerous efforts have attempted to use cross-layer design (CLD) approaches to improve the performance of various networked applications. However, the existing research rarely considers large-scale networks and congestion network conditions in WNCSs. In addition, there is a lack of discussions on how to apply CLD approaches in WNCSs. This thesis proposes a cross-layer design methodology to address the issues of periodic traffic timeliness, as well as to promote the efficiency of channel utilization in WNCSs. The design of the proposed CLD is highlighted by the measurement of the underlying network condition, the classification of the network state, and the adjustment of sampling period between sensors and controllers. This period adjustment is able to maintain the minimally allowable sampling period, and also maximize the control performance. Extensive simulations are conducted using the network simulator NS-2 to evaluate the performance of the proposed CLD. The comparative studies involve two aspects of communications, with and without using the proposed CLD, respectively. The results show that the proposed CLD is capable of fulfilling the timeliness requirement under congested network conditions, and is also able to improve the channel utilization efficiency and the proportion of effective data in WNCSs.

Adsorption of carbon dioxide and nitrogen on single-layer aluminum nitride nanostructures studied by density functional theory

The adsorption of carbon dioxide and nitrogen molecules on aluminum nitride (AlN) nanostructures has been explored using first-principle computational methods. Optimized configurations corresponding to physisorption and, subsequentially, chemisorption of CO2 are identified, in contrast to N2, for which only a physisorption structure is found. Transition-state searches imply a low energy barrier between the physisorption and chemisorption states for CO2 such that the latter is accessible and thermodynamically favored at room temperature. The effective binding energy of the optimized chemisorption structure is apparently larger than those for other CO2 adsorptive materials, suggesting the potential for application of aluminum nitride nanostructures for carbon dioxide capture and storage.

Half metallicity in a zigzag double-walled nanotube nanodot : an Ab initio prediction

Ab initio density functional calculations were performed to study finite-length zigzag (7, 0) @ (16, 0) double-walled carbon nanotubes (DWCNTs) with H-termination at the open ends. We find that such a DWCNT nanodot displays a very large magnetic moment at the zigzag edges and the ground state displays symmetric anti-ferromagnetic coupling. When an external electric field is applied along the direction of tube axis, a gap is opened for one spin channel, whereas another spin channel remains metallic, i.e. half metallicity occurs. Our results suggest an important new avenue for the development of CNT-based spintronic materials with enhanced properties.

Community response to disasters in Indonesia : Gotong Royong; a double edged-sword

Indonesia is a country spread across wide-ranging archipelago, located in South East Asia between two oceans, the Indian and the Pacific. Indonesia is well known as an active tectonic region because it lies on top of three major active tectonic plates: the Eurasian in the North, the Indian Ocean-Australian in the South, and the Pacific plate in the East. The southern and eastern part of the country features a range of volcanic arcs, volcanic mountains, and lowlands with 500 young volcanoes, of which 128 are active and thus representing 15% of the world’s active volcanoes. In the period 2002-2007, approximately 1782 disasters occurred, with hundreds of thousands of lives lost and billions of rupiah in losses incurred: (Floods - 1183 instances, cyclones - 272 instances, and landslides - 252 instances). Of these, the 2004 Aceh tsunami and the 2006 central Java earthquake (impacting predominantly city and suburbs of Yogyakarta) were the most significant. Even so, disaster management experts believe lessons learnt from the two major natural disasters needs to be formalised into laws and institutions before another disaster occurs, regardless of the type of natural disaster – i.e. Volcano eruption or landslide; as opposed to tsunami or earthquake. Following in the wake of disasters occurring in Yogyakarta, many of its community members responded by banding together as one, with the determination of rebuilding its villages and cities through the spirit of ‘gotong royong’. The idea of social interaction; in particular as a collective, consensual, and cooperative nation; has predominantly formed the ideological basis of Indonesia’s societal nature. Many Indonesian terms cohere to this ideology, such as: ‘koperasi” (cooperatives as the basis of economic interactions), ‘musyawarah’ (consensual nature in decision making), and ‘gotong royong’ (mutual assistance). ‘Gotong royong’ has become a key cultural operator in Indonesia, in particular In Jogjakarta. Appropriately so as ‘gotong royong’ is depicted from the traditional Javanese village, where labour is accomplished through reciprocal exchange and the villagers are motivated by a general ethos of selfishness and concern for the common good. The culture of ‘gotong royong’ promotes positive values such as social harmony and mutual reciprocation in disaster-affected areas provides the necessary spirit needed to endure the hardships and for all involved. While gotong royong emphasises the positive notions of mutual family support and deep community level activity there is a potential for contrast against government lead disaster response and recovery management activities especially in settings where sporadic governance mechanisms exist and transparency and accountability in the recovery process of public infrastructure assets have been questioned. This paper thus questions whether Gotong Royong is a double-edged sword, and explores the potential marriage of community values and governance mechanisms for future disaster management planning and practice.

Double tax agreements and the international allocation of business income in Australia

Increasingly, the effectiveness of the present system of taxation of international businesses is being questioned. The problem associated with the taxation of such businesses is twofold. A system of international taxation must be a fair and equitable system, distributing profits between the relevant jurisdictions and, in doing so, avoiding double taxation. At the same time, the prevention of fiscal evasion must be secured. In an attempt to achieve a fair and equitable system Australia adopts unilateral, bilateral and multilateral measures to avoid double taxation and restrict the avoidance of tax. The first step in ascertaining the international allocation of business income is to consider the taxation of business income according to domestic law, that is, the unilateral measures. The treatment of international business income under the Australian domestic law, that is, the Income Tax Assessment Act 1936 (Cth) and Income Tax Assessment Act 1997 (Cth), will depend on two concepts, first, whether the taxpayer is a resident of Australia and secondly, whether the income is sourced in Australia. After the taxation of business profits has been determined according to domestic law it is necessary to consider the applicability of the bilateral measures, that is, the Double Tax Agreements (DTAs) to which Australia is a party, as the DTAs will override the domestic law where there is any conflict. Australia is a party to 40 DTAs with another seven presently being negotiated. The preamble to Australia's DTAs provides that the purpose of such agreements is 'to conclude an Agreement for the avoidance of double taxation and the prevention of fiscal evasion with respect to taxes on income'. Both purposes, for different reasons, are equally important. It has been said that: The taxpayer hopes the treaty will prevent the double taxation of his income; the tax gatherer hopes the treaty will prevent fiscal evasion; and the politician just hopes. The first purpose, the avoidance of double taxation, is achieved through the provision of rules whereby the Contracting States agree to the classification of income and the allocation of that income to a particular State. In this sense DTAs do not allocate jurisdiction to tax but rather provide an arrangement whereby the States agree to restrict their substantive law. The restriction is either through the non-taxing of the income or via the provision of a tax credit.

Double standards in special medical research : questioning the discrepancy between requirements for medical research involving incompetent adults and medical research involving children

Medical research represents a substantial departure from conventional medical care. Medical care is patient-orientated, with decisions based on the best interests and/or wishes of the person receiving the care. In contrast, medical research is future-directed. Primarily it aims to contribute new knowledge about illness or disease, or new knowledge about interventions, such as drugs, that impact upon some human condition. Current State and Territory laws and research ethics guidelines in Australia relating to the review of medical research appropriately acknowledge that the functions of medical care and medical research differ. Prior to a medical research project commencing, the study must be reviewed and approved by a Human Research Ethics Committee (HREC). For medical research involving incompetent adults, some jurisdictions require an additional, independent safeguard by way of tribunal or court approval of medical research protocols. This extra review process reflects the uncertainty of medical research involvement, and the difficulties surrogate decision-makers of incompetent adults face in making decisions about others, and deliberating about the risks and benefits of research involvement. Parents of children also face the same difficulties when making decisions about their child’s research involvement. However, unlike the position concerning incompetent adults, there are no similar safeguards under Australian law in relation to the approval of medical research involving children. This column questions why this discrepancy exists with a view to generating further dialogue on the topic.

Randomised, double blind, placebo-controlled trial of Echinacea supplementation in air travellers

Objective. To identify whether a standardised Echinacea formulation is effective in the prevention of respiratory and other symptoms associated with long-haul flights. Methods. 175 adults participated in a randomised, double-blind placebo-controlled trial travelling back from Australia to America, Europe, or Africa for a period of 1–5 weeks on commercial flights via economy class. Participants took Echinacea (root extract, standardised to 4.4 mg alkylamides) or placebo tablets. Participants were surveyed before, immediately after travel, and at 4 weeks after travel regarding upper respiratory symptoms and travel-related quality of life. Results. Respiratory symptoms for both groups increased significantly during travel (

Flexural and shear bond characteristics of thin layer polymer cement mortared concrete masonry

This paper presents an experimental investigation of the flexural and shear bond characteristics of thin layer polymer cement mortared concrete masonry. It is well known that the bond characteristics of masonry depend upon the mortar type, the techniques of dispersion of mortar and the surface texture of concrete blocks; there exists an abundance of literature on the conventional 10 mm thick cement mortared masonry bond; however, 1-4 mm thick polymer cement mortared masonry bond is not yet well researched. This paper reports a study on the examination of the effect of mortar compositions, dispersion methods and unit surface textures to the flexural and shear bond characteristics of thin layer mortared concrete masonry. A non-contact digital image correlation method was adopted for the measurement of strains at the unit-mortar interface in this research. All mortar joints have been carefully prepared to ensure achievement of the desired thin layer mortar thickness on average. The results exhibit that the bond strength of thin mortar layered concrete masonry with polymer cement mortar is higher than that of the conventional masonry; moreover the unit surface texture and the mortar dispersion methods are found to have significant influence on the flexural and shear bond characteristics. From the experimental results, a correlation between the flexural and the shear bond strengths has been determined and is presented in this paper.

Vibrational spectroscopic study of the natural layered double hydroxide manasseite now defined as hydrotalcite-2H – Mg6Al2(OH)16[CO3]⋅4H2O

Raman and thermo-Raman spectroscopy have been applied to study the mineral formerly known as manasseite now simply renamed as hydrotalcite-2H Mg6Al2(OH)16[CO3]⋅4H2O. The mineral is a member of the homonymous hydrotalcite supergroup. Hydrogen bond distances calculated using a Libowitzky-type empirical function varied between 2.61 and 3.00 Å. Stronger hydrogen bonds were formed by water units as compared to the hydroxyl units. Raman spectroscopy enabled the identification of bands attributed to the hydroxyl units. Two Raman bands at 1059 and 1064 cm-1 are assigned to symmetric stretching modes of the carbonate anion. Thermal treatment shifts these bands to higher wavenumbers indicating a change in the strength of the carbonate bonding.

Validating SMPS-measured size distribution of double-mode spherical Silica nanoparticles by Transmission Electron Microscope (TEM)

A nanoparticles size is one of their key physical characteristics that can affect their fate in a human’s respiratory tract (in case of inhalation) and also in the environment. Hence, measuring the size distribution of nanoparticles is absolutely essential and contributes greatly to their characterization. For years, Scanning Mobility Particle Sizers (SMPS), which rely on measuring the electrical mobility diameter of particles, have been used as one of the most reliable real-time instruments for the size distribution measurement of nanoparticles. Despite its benefits, this instrument has some drawbacks, including equivalency problems for non-spherical particles (i.e. assuming a non-spherical particle is equal to a spherical particle of diameter d due to the same electrical mobility), as well as limitations in terms of its use in workplaces, because of its large size and the complexity of its operation...

Double strap joint tests to determine the bond characteristics between CFRP and steel plates

Advanced composite materials offer remarkable potential in the upgrade of civil engineering structures. The evolution of CFRP (carbon fibre reinforced polymer) technologies and their versatility for applications in civil constructions require comprehensive and reliable codes of practice. Guidelines are available on the rehabilitation and retrofit of concrete structures with advanced composite materials. However, there is a need to develop appropriate design guidelines for CFRP strengthened steel structures. It is important to understand the bond characteristics between CFRP and steel plates. This paper describes a series of double strap shear tests loaded in tension to investigate the bond between CFRP sheets and steel plates. Both normal modulus (240 GPa) and high modulus (640 GPa) CFRPs were used in the test program. Strain gauges were mounted to capture the strain distribution along the CFRP length. Different failure modes were observed for joints with normal modulus CFRP and those with high modulus CFRP. The strain distribution along the CFRP length is similar for the two cases. A shorter effective bond length was obtained for joints with high modulus CFRP whereas larger ultimate load carrying capacity can be achieved for joints with normal modulus CFRP when the bond length is long enough.

Simulation of Au particle interaction on graphene sheets

The interaction of Au particles with few layer graphene is of interest for the formation of the next generation of sensing devices(1). In this paper we investigate the coupling of single gold nanoparticles to a graphene sheet, and multiple gold nanoparticles with a graphene sheet using COMSOL Multiphysics. By using these simulations we are able to determine the electric field strength and associated hot-spots for various gold nanoparticle-graphene systems. The Au nanoparticles were modelled as 8 nm diameter spheres on 1.5 nm thick (5 layers) graphene, with properties of graphene obtained from the refractive index data of Weber(2) and the Au refractive index data from Palik(3). The field was incident along the plane of the sheet with polarisation tested for both s and p. The study showed strong localised interaction between the Au and graphene with limited spread; however the double particle case where the graphene sheet separated two Au nanoparticles showed distinct interaction between the particles and graphene. An offset was introduced (up to 4 nm) resulting in much reduced coupling between the opposed particles as the distance apart increased. Findings currently suggest that the graphene layer has limited interaction with incident fields with a single particle present whilst reducing the coupling region to a very fine area when opposing particles are involved. It is hoped that the results of this research will provide insight into graphene-plasmon interactions and spur the development of the next generation of sensing devices.