A simple model of electron beam initiated dielectric breakdown

A steady state model that describes the internal charge distribution of a planar dielectric sample exposed to a uniform electron beam was developed. The model includes the effects of charge deposition and ionization of the beam, separate trap-modulated mobilities for electrons and holes, electron-hole recombination, and pair production by drifting thermal electrons. If the incident beam current is greater than a certain critical value (which depends on sample thickness as well as other sample properties), the steady state solution is non-physical

Genetic Engineering to Enhance Mercury Phytoremediation

Most phytoremediation studies utilize merA or merB genes to modify plants via the nuclear or chloroplast genome, expressing organomercurial lyase and/or mercuric ion reductase in the cytoplasm, endoplasmic reticulum or within plastids. Several plant species including Arabidopsis, tobacco, poplar, rice, Eastern cottonwood, peanut, salt marsh grass and Chlorella have been transformed with these genes. Transgenic plants grew exceedingly well in soil contaminated with organic (~400 μM PMA) or inorganic mercury (~500 μM HgCl2), accumulating Hg in roots surpassing the concentration in soil (~2000 μg/g). However, none of these plants were tested in the field to demonstrate real potential of this approach. Availability of metal transporters, translocators, chelators and the ability to express membrane proteins could further enhance mercury phytoremediation capabilities

Characterization of Heterologous Multigene Operons in Transgenic Chloroplasts. Transcription, Processing, and Translation1

The first characterization of transcriptional, posttranscriptional, and translational processes of heterologous operons expressed via the tobacco (Nicotiana tabacum) chloroplast genome is reported here. Northern-blot analyses performed on chloroplast transgenic lines harboring seven different heterologous operons revealed that polycistronic mRNA was the predominant transcript produced. Despite the lack of processing of such polycistrons, large amounts of foreign protein accumulation was observed in these transgenic lines, indicating abundant translation of polycistrons. This is supported by polysome fractionation assays, which allowed detection of polycistronic RNA in lower fractions of the sucrose gradients. These results show that the chloroplast posttranscriptional machinery can indeed detect and translate multigenic sequences that are not of chloroplast origin. In contrast to native transcripts, processed and unprocessed heterologous polycistrons were stable, even in the absence of 3′ untranslated regions (UTRs). Unlike native 5′UTRs, heterologous secondary structures or 5′UTRs showed efficient translational enhancement independent of cellular control. Abundant read-through transcripts were observed in the presence of chloroplast 3′UTRs but they were efficiently processed at introns present within the native operon. Heterologous genes regulated by the psbA (the photosystem II polypeptide D1) promoter, 5′ and 3′UTRs have greater abundance of transcripts than the endogenous psbA gene because transgenes were integrated into the inverted repeat region. Addressing questions about polycistrons, and the sequences required for their processing and transcript stability, are essential in chloroplast metabolic engineering. Knowledge of such factors would enable engineering of foreign pathways independent of the chloroplast complex posttranscriptional regulatory machinery

Evaluation of biolistic gene transfer methods in vivo using non-invasive bioluminescent imaging techniques

<p>Abstract</p> <p>Background</p> <p>Gene therapy continues to hold great potential for treating many different types of disease and dysfunction. Safe and efficient techniques for gene transfer and expression in vivo are needed to enable gene therapeutic strategies to be effective in patients. Currently, the most commonly used methods employ replication-defective viral vectors for gene transfer, while physical gene transfer methods such as biolistic-mediated ("gene-gun") delivery to target tissues have not been as extensively explored. In the present study, we evaluated the efficacy of biolistic gene transfer techniques in vivo using non-invasive bioluminescent imaging (BLI) methods.</p> <p>Results</p> <p>Plasmid DNA carrying the firefly luciferase (LUC) reporter gene under the control of the human Cytomegalovirus (CMV) promoter/enhancer was transfected into mouse skin and liver using biolistic methods. The plasmids were coupled to gold microspheres (1 μm diameter) using different DNA Loading Ratios (DLRs), and "shot" into target tissues using a helium-driven gene gun. The optimal DLR was found to be in the range of 4-10. Bioluminescence was measured using an In Vivo Imaging System (IVIS-50) at various time-points following transfer. Biolistic gene transfer to mouse skin produced peak reporter gene expression one day after transfer. Expression remained detectable through four days, but declined to undetectable levels by six days following gene transfer. Maximum depth of tissue penetration following biolistic transfer to abdominal skin was 200-300 μm. Similarly, biolistic gene transfer to mouse liver in vivo also produced peak early expression followed by a decline over time. In contrast to skin, however, liver expression of the reporter gene was relatively stable 4-8 days post-biolistic gene transfer, and remained detectable for nearly two weeks.</p> <p>Conclusions</p> <p>The use of bioluminescence imaging techniques enabled efficient evaluation of reporter gene expression in vivo. Our results demonstrate that different tissues show different expression kinetics following gene transfer of the same reporter plasmid to different mouse tissues in vivo. We evaluated superficial (skin) and abdominal organ (liver) targets, and found that reporter gene expression peaked within the first two days post-transfer in each case, but declined most rapidly in the skin (3-4 days) compared to liver (10-14 days). This information is essential for designing effective gene therapy strategies in different target tissues.</p

Aiding multi-level decision-making processes for climate change mitigation and adaptation

Progress towards climate change aware regional sustainable development is affected by actions at multiple spatial scales and governance levels and equally impacts actions at these scales. Many authors and policy practitioners consider therefore that decisions over policy, mitigation strategies and capacity for adaptation to climate change require construction and coordination over multiple levels of governance to arrive at acceptable local, regional and global management strategies. However, how such processes of coordination and decision-aiding can occur and be maintained and improved over time is a major challenge in need of investigation. We take on this challenge by proposing research-supported methods of aiding multi-level decision-making processes in this context. Four example regionally focussed multi-level case studies from diverse socio-political contexts are outlined-estuarine management in Australia's Lower Hawkesbury, flood and drought management in Bulgaria's Upper Iskar Basin, climate policy integration in Spain's Comunidad Valenciana and food security in Bangladesh's Faridpur District-from which insights are drawn. Our discussion focuses on exploring these insights including: (1) the possible advantages of informal research-supported processes and specifically those that provide individual arenas of participation for different levels of stakeholders; (2) the complexity of organisation processes required for aiding multi-level decision-making processes; and (3) to what extent progress towards integrated regional policies for climate change aware sustainable development can be achieved through research-supported processes. We finish with a speculative section that provides ideas and directions for future research

Immigration Federalism: A Reappraisal

This Article identifies how the current spate of state and local regulation is changing the way elected officials, scholars, courts, and the public think about the constitutional dimensions of immigration law and governmental responsibility for immigration enforcement. Reinvigorating the theoretical possibilities left open by the Supreme Court in its 1875 Chy Lung v. Freeman decision, state and local offi- cials characterize their laws as unavoidable responses to the policy problems they face when they are squeezed between the challenges of unauthorized migration and the federal government’s failure to fix a broken system. In the October 2012 term, in Arizona v. United States, the Court addressed, but did not settle, the difficult empirical, theoretical, and constitutional questions necessitated by these enactments and their attendant justifications. Our empirical investigation, however, discovered that most state and local immigration laws are not organic policy responses to pressing demographic challenges. Instead, such laws are the product of a more nuanced and politicized process in which demographic concerns are neither neces- sary nor sufficient factors and in which federal inactivity and subfederal activity are related phenomena, fomented by the same actors. This Article focuses on the con- stitutional and theoretical implications of these processes: It presents an evidence- based theory of state and local policy proliferation; it cautions legal scholars to rethink functionalist accounts for the rise of such laws; and it advises courts to reassess their use of traditional federalism frameworks to evaluate these sub federal enactments

Complete Nucleotide Sequence of Dendrocalamus Latiflorus and Bambusa Oldhamii Chloroplast Genomes

Although bamboo is one of the most important woody crops in Asia, information on its genome is still very limited. To investigate the relationship among Poaceae members and to understand the mechanism of albino mutant generation in vitro, the complete chloroplast genome of two economically important bamboo species, Dendrocalamus latiflorus Munro and Bambusa oldhamii Munro, was determined employing a strategy that involved polymerase chain reaction (PCR) amplification using 443 novel primers designed to amplify the chloroplast genome of these two species. The lengths of the B. oldhamii and D. latiflorus chloroplast genomes are 139,350 and 139,365 bp, respectively. The organization structure and the gene order of these two bamboos are identical to other members of Poaceae. Highly conserved chloroplast genomes of Poaceae facilitated sequencing by the PCR method. Phylogenetic analysis using both chloroplast genomes confirmed the results obtained from studies on chromosome number and reproductive organ morphology. There are 23 gaps, insertions/deletions \u3e 100 bp, in the chloroplast genomes of 10 genera of Poaceae compared in this study. The phylogenetic distribution of these gaps corresponds to their taxonomic placement. The sequences of these two chloroplast genomes provide useful information for studying bamboo evolution, ecology and biotechnology

Patterns and Predictors of Healthcare Use among Adolescent and Young Adult Cancer Survivors versus a Community Comparison Group.

Healthcare use (HCU) during survivorship can mitigate adolescent and young adult (AYA) cancer survivors' (aged 15-39 years) risk of medical and psychosocial late effects, but this is understudied. We surveyed 93 Australian AYA post-treatment cancer survivors (Mage = 22.0 years, SD = 3.5; 55.9% female) and a comparison sample of 183 non-matched AYAs (Mage = 19.7, SD = 3.2; 70.5% female) on their HCU, medication use, depression/anxiety, and general functioning. Relative to our comparison AYAs, a higher proportion of our survivor group reported medical HCU (community-delivered: 65.6% versus 47.0%, p = 0.003; hospital-delivered: 31.2% versus 20.3%, p = 0.044) and mental HCU (53.8% vs. 23.5%; p < 0.0001) in the past six months. A higher proportion of our survivors reported taking medications within the past six months than our comparison AYAs (61.3% vs. 42.1%, p = 0.003) and taking more types (p < 0.001). Vitamin/supplement use was most common followed by psychotropic medications. Our survivor group reported lower depression (p = 0.001) and anxiety symptoms (p = 0.003), but similar work/study participation (p = 0.767) to our comparison AYAs. Across groups, psychological distress was associated with higher mental HCU (p = 0.001). Among survivors, those who were female, diagnosed with brain/solid tumors and who had finished treatment more recently reported greater HCU. Future research should establish whether this level of HCU meets AYAs' survivorship needs

Observation of three-photon Greenberger-Horne-Zeilinger entanglement

We present the experimental observation of polarization entanglement for three spatially separated photons. Such states of more than two entangled particles, known as GHZ states, play a crucial role in fundamental tests of quantum mechanics versus local realism and in many quantum information and quantum computation schemes. Our experimental arrangement is such that we start with two pairs of entangled photons and register one photon in a way that any information as to which pair it belongs to is erased. The registered events at the detectors for the remaining three photons then exhibit the desired GHZ correlations.Comment: Revtex, 4 pages, uses floats, epsfi