Geophysical and atmospheric evolution of habitable planets

The evolution of Earth-like habitable planets is a complex process that depends on the geodynamical and geophysical environments. In particular, it is necessary that plate tectonics remain active over billions of years. These geophysically active environments are strongly coupled to a planet's host star parameters, such as mass, luminosity and activity, orbit location of the habitable zone, and the planet's initial water inventory. Depending on the host star's radiation and particle flux evolution, the composition in the thermosphere, and the availability of an active magnetic dynamo, the atmospheres of Earth-like planets within their habitable zones are differently affected due to thermal and nonthermal escape processes. For some planets, strong atmospheric escape could even effect the stability of the atmosphere

Pathogen Inactivating Properties and Increased Sensitivity in Molecular Diagnostics by PAXgene, a Novel Non-Crosslinking Tissue Fixative.

BACKGROUND:Requirements on tissue fixatives are getting more demanding as molecular analysis becomes increasingly relevant for routine diagnostics. Buffered formaldehyde in pathology laboratories for tissue fixation is known to cause chemical modifications of biomolecules which affect molecular testing. A novel non-crosslinking tissue preservation technology, PAXgene Tissue (PAXgene), was developed to preserve the integrity of nucleic acids in a comparable way to cryopreservation and also to preserve morphological features comparable to those of formalin fixed samples. METHODS:Because of the excellent preservation of biomolecules by PAXgene we investigated its pathogen inactivation ability and biosafety in comparison to formalin by in-vitro testing of bacteria, human relevant fungi and human cytomegalovirus (CMV). Guidelines for testing disinfectants served as reference for inactivation assays. Furthermore, we tested the properties of PAXgene for detection of pathogens by PCR based assays. RESULTS:All microorganisms tested were similarly inactivated by PAXgene and formalin except Clostridium sporogenes, which remained viable in seven out of ten assays after PAXgene treatment and in three out of ten assays after formalin fixation. The findings suggest that similar biosafety measures can be applied for PAXgene and formalin fixed samples. Detection of pathogens in PCR-based diagnostics using two CMV assays resulted in a reduction of four to ten quantification cycles of PAXgene treated samples which is a remarkable increase of sensitivity. CONCLUSION:PAXgene fixation might be superior to formalin fixation when molecular diagnostics and highly sensitive detection of pathogens is required in parallel to morphology assessment

Investigated strains cover the spectrum of bacterial life conditions.

<p>Specific media were used for bacteria cultivation before and after inactivation treatment.</p

a,b,c,d,e,f,g: Results of bacterial inactivation experiments after treatment with PAXgene and formalin.

<p>Bacterial strains show variable viability after treatment with PAXgene Fix, PAXgene Fix and Stab compared to formalin and PBS (viability control) for 30 minutes (a, b, c, e, f, g) and 2 hours (d). The x-axis indicates the amount of experiments, the y-axis cfu/ml. To obtain comparable results all counted cfus were normalised to 10⁶. Columns represent the mean values (and error bars) calculated from the results of a series of different dilutions for one experiment. Dashed lines indicate the reduction limit of 10⁵.</p

Work flow of bacterial and fungal inactivation experiments.

<p>Work flow of bacterial and fungal experiments. Bacteria experiments were performed with four (<i>Pa</i>) and six (<i>Ms</i>) independent experiments, respectively, when no colony was detected after inactivation, six experiments if colonies were detected (<i>Bs</i>, <i>Sa and Mt</i>) and seven experiments with the most variable strain <i>Cs</i>. Two-hour-treatments were performed with fungi (two experiments and all strains listed in <a href="http://www.plosone.org/article/info:doi/10.1371/journal.pone.0151383#pone.0151383.t001" target="_blank">Table 1</a>) and additionally with <i>Cs</i> (three experiments).</p

Reverse transcription qPCR: comparison of Cq values of PAXgene and formalin-fixed CMV samples.

<p>RT-qPCR sensitivity assay was performed to detect CMV early-immediate gene <i>TRS1</i> and reference gene <i>GAPDH</i> after fixation of CMV infected MRC-5 cells with PAXgene (<i>TRS1</i>_PF, <i>GAPDH</i>_PF), formalin (<i>TRS1</i>_FF, <i>GAPDH</i>_FF) and not fixed control samples (<i>TRS1</i>_PBS; <i>GAPDH</i>_PBS) in triple biological samples. Low Cq values indicate early detection. Statistical significance p < 0.0001 (***) or p < 0.03 (*).</p

a,b: Results of inactivation experiments of human-relevant fungi by two hours fixation with PBS as positive control, PAXgene Fix, PAXgene Fix and Stab, and formalin.

<p>At least two assays per species (1–3 experiments) were performed. a) Cfu/mL was normalised to 10⁵. The dashed line indicates the threshold for minimum of reduction of 10⁴ used for disinfectants for fungi. b) Bold printed numbers indicate minimal growth after inactivation.</p

Human relevant fungi cultivated, treated with PAXgene and formalin and investigated for viability.

<p>Human relevant fungi cultivated, treated with PAXgene and formalin and investigated for viability.</p

Recent Developments for the estimation of the altimeter bias for the Jason-1&2 satellites using the dedicated calibration site at Gavdos

Summarization: The dedicated calibration site for satellite radar altimeters in Gavdos has been operational as of 2004. The small island of Gavdos is located along a repeating ground track of Jason satellites (crossover point No 109 ascending and No. 18 descending pass and adjacent to Envisat), and where the altimeter and radiometer footprints do not experience significant land intrusion. The purpose of such permanent Cal/Val facility is to calibrate the sea-surface height and ancillary measurements made by the satellite as it passes overhead, by using observations from tide gauges, GPS, DORIS and other sensors directly placed under the satellite ground tracks. The successful launch of Jason-2 satellite (20 June, 2008) initiated its calibration-validation phase. This was achieved having the two satellites flying with less than one minute difference and in the same orbit. Using the Gavdos calibration facility the following have been determined: (1) the absolute altimeter bias of Jason-1 satellite for the cycles 209-259; using GDR-C data; (2) the absolute altimeter bias of Jason-2 satellite for the cycles 2-28 using GDR-A data ; (3) the inter- mission bias for the period July 2008 – January 2009. The expansion of the Gavdos Cal/Val facilities with the deployment of a new site in the south of Crete and along pass No. 109 is also presented in this work.Παρουσιάστηκε στο: SPIE, Remote Sensing of the Ocean, Sea Ice, and Land Water Regions 200