Visible and near infrared spectroscopy of Hayabusa re-entry using semi-autonomous tracking

A ground-based tracking camera and co-aligned slit-less spectrograph were used to measure the spectral signature of visible radiation emitted from the Hayabusa capsule as it entered into the Earth's atmosphere in June 2010. Good quality spectra were obtained that showed the presence of radiation from the heat shield of the vehicle and the shock-heated air in front of the vehicle. An analysis of the black body nature of the radiation concluded that the peak average temperature of the surface was about (3100±100) K

Radiometric temperature analysis of the Hayabusa spacecraft re-entry

Hayabusa, an unmanned Japanese spacecraft, was launched to study and collect samples from the surface of the asteroid 25143 Itokawa. In June 2010, the Hayabusa spacecraft completed it’s seven year voyage. The spacecraft and the sample return capsule (SRC) re-entered the Earth’s atmosphere over the central Australian desert at speeds on the order of 12 km/s. This provided a rare opportunity to experimentally investigate the radiative heat transfer from the shock-compressed gases in front of the sample return capsule at true-flight conditions. This paper reports on the results of observations from a tracking camera situated on the ground about 100 km from where the capsule experienced peak heating during re-entry

Benznidazole biotransformation and multiple targets in <i>Trypanosoma</i> cruzi revealed by metabolomics

&lt;b&gt;Background&lt;/b&gt;&lt;p&gt;&lt;/p&gt; The first line treatment for Chagas disease, a neglected tropical disease caused by the protozoan parasite Trypanosoma cruzi, involves administration of benznidazole (Bzn). Bzn is a 2-nitroimidazole pro-drug which requires nitroreduction to become active, although its mode of action is not fully understood. In the present work we used a non-targeted MS-based metabolomics approach to study the metabolic response of T. cruzi to Bzn.&lt;p&gt;&lt;/p&gt; &lt;b&gt;Methodology/Principal findings&lt;/b&gt;&lt;p&gt;&lt;/p&gt; Parasites treated with Bzn were minimally altered compared to untreated trypanosomes, although the redox active thiols trypanothione, homotrypanothione and cysteine were significantly diminished in abundance post-treatment. In addition, multiple Bzn-derived metabolites were detected after treatment. These metabolites included reduction products, fragments and covalent adducts of reduced Bzn linked to each of the major low molecular weight thiols: trypanothione, glutathione, γ-glutamylcysteine, glutathionylspermidine, cysteine and ovothiol A. Bzn products known to be generated in vitro by the unusual trypanosomal nitroreductase, TcNTRI, were found within the parasites, but low molecular weight adducts of glyoxal, a proposed toxic end-product of NTRI Bzn metabolism, were not detected.&lt;p&gt;&lt;/p&gt; &lt;b&gt;Conclusions/significance&lt;/b&gt;&lt;p&gt;&lt;/p&gt; Our data is indicative of a major role of the thiol binding capacity of Bzn reduction products in the mechanism of Bzn toxicity against T. cruzi

Restriction Site Extension PCR: A Novel Method for High-Throughput Characterization of Tagged DNA Fragments and Genome Walking

BACKGROUND: Insertion mutant isolation and characterization are extremely valuable for linking genes to physiological function. Once an insertion mutant phenotype is identified, the challenge is to isolate the responsible gene. Multiple strategies have been employed to isolate unknown genomic DNA that flanks mutagenic insertions, however, all these methods suffer from limitations due to inefficient ligation steps, inclusion of restriction sites within the target DNA, and non-specific product generation. These limitations become close to insurmountable when the goal is to identify insertion sites in a high throughput manner. METHODOLOGY/PRINCIPAL FINDINGS: We designed a novel strategy called Restriction Site Extension PCR (RSE-PCR) to efficiently conduct large-scale isolation of unknown genomic DNA fragments linked to DNA insertions. The strategy is a modified adaptor-mediated PCR without ligation. An adapter, with complementarity to the 3' overhang of the endonuclease (KpnI, NsiI, PstI, or SacI) restricted DNA fragments, extends the 3' end of the DNA fragments in the first cycle of the primary RSE-PCR. During subsequent PCR cycles and a second semi-nested PCR (secondary RSE-PCR), touchdown and two-step PCR are combined to increase the amplification specificity of target fragments. The efficiency and specificity was demonstrated in our characterization of 37 tex mutants of Arabidopsis. All the steps of RSE-PCR can be executed in a 96 well PCR plate. Finally, RSE-PCR serves as a successful alternative to Genome Walker as demonstrated by gene isolation from maize, a plant with a more complex genome than Arabidopsis. CONCLUSIONS/SIGNIFICANCE: RSE-PCR has high potential application in identifying tagged (T-DNA or transposon) sequence or walking from known DNA toward unknown regions in large-genome plants, with likely application in other organisms as well

Experimental study of the quantum driven pendulum and its classical analogue in atoms optics

We present experimental results for the dynamics of cold atoms in a far detuned amplitude-modulated optical standing wave. Phase-space resonances constitute distinct peaks in the atomic momentum distribution containing up to 65% of all atoms resulting from a mixed quantum chaotic phase space. We characterize the atomic behavior in classical and quantum regimes and we present the applicable quantum and classical theory, which we have developed and refined. We show experimental proof that the size and the position of the resonances in phase space can be controlled by varying several parameters, such as the modulation frequency, the scaled well depth, the modulation amplitude, and the scaled Planck's constant of the system. We have found a surprising stability against amplitude noise. We present methods to accurately control the momentum of an ensemble of atoms using these phase-space resonances which could be used for efficient phase-space state preparation