Chapter 9 Gene Drive Strategies for Population Replacement

Gene drive systems are selfish genetic elements capable of spreading into a population despite a fitness cost. A variety of these systems have been proposed for spreading disease-refractory genes into mosquito populations, thus reducing their ability to transmit diseases such as malaria and dengue fever to humans. Some have also been proposed for suppressing mosquito populations. We assess the alignment of these systems with design criteria for their safety and efficacy. Systems such as homing endonuclease genes, which manipulate inheritance through DNA cleavage and repair, are highly invasive and well-suited to population suppression efforts. Systems such as Medea, which use combinations of toxins and antidotes to favor their own inheritance, are highly stable and suitable for replacing mosquito populations with disease-refractory varieties. These systems offer much promise for future vector-borne disease control

Sequence Expression of Supernumerary B Chromosomes: Function or Fluff?

B chromosomes are enigmatic heritable elements found in the genomes of numerous plant and animal species. Contrary to their broad distribution, most B chromosomes are non-essential. For this reason, they are regarded as genome parasites. In order to be stably transmitted through generations, many B chromosomes exhibit the ability to "drive", i.e., they transmit themselves at super-Mendelian frequencies to progeny through directed interactions with the cell division apparatus. To date, very little is understood mechanistically about how B chromosomes drive, although a likely scenario is that expression of B chromosome sequences plays a role. Here, we highlight a handful of previously identified B chromosome sequences, many of which are repetitive and non-coding in nature, that have been shown to be expressed at the transcriptional level. We speculate on how each type of expressed sequence could participate in B chromosome drive based on known functions of RNA in general chromatin- and chromosome-related processes. We also raise some challenges to functionally testing these possible roles, a goal that will be required to more fully understand whether and how B chromosomes interact with components of the cell for drive and transmission

Magnetsko-optička svojstva legure In1−xGaxP

The room-temperature dependence on composition of the energy gap is measured for the ternary alloy system In1−xGaxP semiconductors. The cross-over point from the direct to indirect optical transition energy gap is found at x = 0.718. An empirical relation for the alloy system energy-gap dependence is found for both direct and indirect transition regions. From the empirical relations belonging to the direct region transition, the values of the expected indirect energy transition at Γc1 are calculated. The difference between these values and the corresponding indirect energy (Γc1−Xc1) are also calculated. The change of Eg due to the effects of magnetic field up to 1.6 T (Tesla) was also measured. The magnetic coefficient is found to be between 3.33×10−7 and 3.87×10−7 eV/T for x = 0.31 to x = 1. A clear deviation of the magnetic coefficient occurred for the change from the direct-region to that of the indirect-region transition.Mjerili smo ovisnost energijskog procijepa u trojnom sustavu poluvodičke legure In1−xGaxP na sobnoj temperaturi. Našli smo prijelaznu točku od izravnih k neizravnim optičkim prijelazima za x = 0.718. Izveli smo iskustvenu ovisnost energijske ovisnosti energijskog procijepa tog sustava za izravne i neizravne prijelaze. Na osnovi iskustvene ovisnosti za područje izravnih prijelaza izračunali smo energiju neizravnih prijelaza za Γc1. Izračunali smo također razlike tih vrijednosti koje odgovaraju energiji neizravnih prijelaza (Γc1−Xc1). Promjene Eg zbog učinaka magnetskog polja mjerili smo do 1.6 T. Našli smo magnetski koeficijent između 3.33 × 10−7 i 3.87 × 10−7 eV/T za x = 0.31 do x = 1. Opaža se jasan otklon magnetskog koeficijenta pri prijelazu od izravnih k neizravnim prijelazima

Magnetsko-optička svojstva legure In1−xGaxP

The room-temperature dependence on composition of the energy gap is measured for the ternary alloy system In1−xGaxP semiconductors. The cross-over point from the direct to indirect optical transition energy gap is found at x = 0.718. An empirical relation for the alloy system energy-gap dependence is found for both direct and indirect transition regions. From the empirical relations belonging to the direct region transition, the values of the expected indirect energy transition at Γc1 are calculated. The difference between these values and the corresponding indirect energy (Γc1−Xc1) are also calculated. The change of Eg due to the effects of magnetic field up to 1.6 T (Tesla) was also measured. The magnetic coefficient is found to be between 3.33×10−7 and 3.87×10−7 eV/T for x = 0.31 to x = 1. A clear deviation of the magnetic coefficient occurred for the change from the direct-region to that of the indirect-region transition.Mjerili smo ovisnost energijskog procijepa u trojnom sustavu poluvodičke legure In1−xGaxP na sobnoj temperaturi. Našli smo prijelaznu točku od izravnih k neizravnim optičkim prijelazima za x = 0.718. Izveli smo iskustvenu ovisnost energijske ovisnosti energijskog procijepa tog sustava za izravne i neizravne prijelaze. Na osnovi iskustvene ovisnosti za područje izravnih prijelaza izračunali smo energiju neizravnih prijelaza za Γc1. Izračunali smo također razlike tih vrijednosti koje odgovaraju energiji neizravnih prijelaza (Γc1−Xc1). Promjene Eg zbog učinaka magnetskog polja mjerili smo do 1.6 T. Našli smo magnetski koeficijent između 3.33 × 10−7 i 3.87 × 10−7 eV/T za x = 0.31 do x = 1. Opaža se jasan otklon magnetskog koeficijenta pri prijelazu od izravnih k neizravnim prijelazima

Geometrical effects on energy transfer in disordered open quantum systems

We explore various design principles for efficient excitation energy transport in complex quantum systems. We investigate energy transfer efficiency in randomly disordered geometries consisting of up to 20 chromophores to explore spatial and spectral properties of small natural/artificial Light-Harvesting Complexes (LHC). We find significant statistical correlations among highly efficient random structures with respect to ground state properties, excitonic energy gaps, multichromophoric spatial connectivity, and path strengths. These correlations can even exist beyond the optimal regime of environment-assisted quantum transport. For random configurations embedded in spatial dimensions of 30 A and 50 A, we observe that the transport efficiency saturates to its maximum value if the systems contain 7 and 14 chromophores respectively. Remarkably, these optimum values coincide with the number of chlorophylls in (Fenna-Matthews-Olson) FMO protein complex and LHC II monomers, respectively, suggesting a potential natural optimization with respect to chromophoric density.Comment: 11 pages, 10 figures. Expanded from the former appendix to arXiv:1104.481

Assessing the readiness of contractors in implementing low carbon construction in Penang

Global warming or climate change is becoming the main concerns of humanity as it leads to an increase in Earth’s temperature and rise in the oceans’ level which is due to the increase of greenhouse gasses in the atmosphere. Greenhouse gasses consists of water vapour, carbon dioxide (CO2), methane (CH4), nitrous oxide (N20), tropospheric ozone (O3) and chlorofluorocarbons (CFCs). Among the gasses, CO2 is the highest and easiest gas to measure as it is emitted from human economic activities with construction industry one of the major contributors of carbon emissions. Low carbon construction is the reduction of carbon emissions from the construction activities during construction process. For the implementation of low carbon construction in our construction industry, the contractors need to be ready and have knowledge to adopt low carbon construction industry. The purpose of this research is to determine the level of contractors’ knowledge towards low carbon construction, determining the level of readiness towards low carbon construction and proposing a checklist for the contractors towards low carbon construction in Penang. This research employed questionnaire survey to analyse the level of knowledge and readiness of the contractors on low carbon construction. As a conclusion, the implementation of low carbon practices by the contractors in Penang is good, therefore established that G7 contractors implement low carbon practices throughout their construction. However, the results and findings indicated that the average mean score on the level of readiness of contractors towards low carbon construction is 3.59. The result was perceived as moderate. Therefore, it shows that the contractors are in a moderate readiness to implement low carbon construction fully in their construction projects. A checklist was established by summarizing the highest low carbon activities from each category which were sustainable site planning and management, materials and resources, waste management, water efficiency and energy efficiency, and was perceived as good. Keywords: Climate change, greenhouse gases, carbon emission, low carbon construction, contractors’ readiness