Selection of systems to perform extravehicular activities, man and manipulator. Volume 1 - Performance Effectiveness Evaluation Scheme /PEEVS/. Part A - Instructions

Performance effectiveness evaluation scheme for EVA systems selection - instruction

Selection of systems to perform extravehicular activities, man and manipulator. Volume 2 - Final report

Technologies for EVA and remote manipulation systems - handbook for systems designer

Dynamics of a bubble formed in double stranded DNA

We study the fluctuational dynamics of a tagged base-pair in double stranded DNA. We calculate the drift force which acts on the tagged base-pair using a potential model that describes interactions at base pairs level and use it to construct a Fokker-Planck equation.The calculated displacement autocorrelation function is found to be in very good agreement with the experimental result of Altan-Bonnet {\it et. al.} Phys. Rev. Lett. {\bf 90}, 138101 (2003) over the entire time range of measurement. We calculate the most probable displacements which predominately contribute to the autocorrelation function and the half-time history of these displacements.Comment: 11 pages, 4 figures. submitted to Phys. Rev. Let

Effect of shear force on the separation of double stranded DNA

Using the Langevin Dynamics simulation, we have studied the effects of the shear force on the rupture of short double stranded DNA at different temperatures. We show that the rupture force increases linearly with the chain length and approaches to the asymptotic value in accordance with the experiment. The qualitative nature of these curves almost remains same for different temperatures but with a shift in the force. We observe three different regimes in the extension of covalent bonds (back bone) under the shear force.Comment: 4 pages, 4 figure

Energy Localization in the Peyrard-Bishop DNA model

We study energy localization on the oscillator-chain proposed by Peyrard and Bishop to model the DNA. We search numerically for conditions with initial energy in a small subgroup of consecutive oscillators of a finite chain and such that the oscillation amplitude is small outside this subgroup for a long timescale. We use a localization criterion based on the information entropy and we verify numerically that such localized excitations exist when the nonlinear dynamics of the subgroup oscillates with a frequency inside the reactive band of the linear chain. We predict a mimium value for the Morse parameter $(\mu >2.25)$ (the only parameter of our normalized model), in agreement with the numerical calculations (an estimate for the biological value is $\mu =6.3$). For supercritical masses, we use canonical perturbation theory to expand the frequencies of the subgroup and we calculate an energy threshold in agreement with the numerical calculations

Experimental and theoretical studies of sequence effects on the fluctuation and melting of short DNA molecules

Understanding the melting of short DNA sequences probes DNA at the scale of the genetic code and raises questions which are very different from those posed by very long sequences, which have been extensively studied. We investigate this problem by combining experiments and theory. A new experimental method allows us to make a mapping of the opening of the guanines along the sequence as a function of temperature. The results indicate that non-local effects may be important in DNA because an AT-rich region is able to influence the opening of a base pair which is about 10 base pairs away. An earlier mesoscopic model of DNA is modified to correctly describe the time scales associated to the opening of individual base pairs well below melting, and to properly take into account the sequence. Using this model to analyze some characteristic sequences for which detailed experimental data on the melting is available [Montrichok et al. 2003 Europhys. Lett. {\bf 62} 452], we show that we have to introduce non-local effects of AT-rich regions to get acceptable results. This brings a second indication that the influence of these highly fluctuating regions of DNA on their neighborhood can extend to some distance.Comment: To be published in J. Phys. Condensed Matte

Digital carbonate rock physics

Modern estimation of rock properties combines imaging with advanced numerical simulations, an approach known as digital rock physics (DRP). In this paper we suggest a specific segmentation procedure of X-ray micro-computed tomography data with two different resolutions in the µm range for two sets of carbonate rock samples. These carbonates were already characterized in detail in a previous laboratory study which we complement with nanoindentation experiments (for local elastic properties). In a first step a non-local mean filter is applied to the raw image data. We then apply different thresholds to identify pores and solid phases. Because of a non-neglectable amount of unresolved microporosity (micritic phase) we also define intermediate threshold values for distinct phases. Based on this segmentation we determine porosity-dependent values for effective P- and S-wave velocities as well as for the intrinsic permeability. For effective velocities we confirm an observed two-phase trend reported in another study using a different carbonate data set. As an upscaling approach we use this two-phase trend as an effective medium approach to estimate the porosity-dependent elastic properties of the micritic phase for the low-resolution images. The porosity measured in the laboratory is then used to predict the effective rock properties from the observed trends for a comparison with experimental data.The two-phase trend can be regarded as an upper bound for elastic properties; the use of the two-phase trend for low-resolution images led to a good estimate for a lower bound of effective elastic properties. Anisotropy is observed for some of the considered subvolumes, but seems to be insignificant for the analysed rocks at the DRP scale. Because of the complexity of carbonates we suggest using DRP as a complementary tool for rock characterization in addition to classical experimental methods

Self-energy limited ion transport in sub-nanometer channels

The current-voltage characteristics of the alpha-Hemolysin protein pore during the passage of single-stranded DNA under varying ionic strength, C, are studied experimentally. We observe strong blockage of the current, weak super-linear growth of the current as a function of voltage, and a minimum of the current as a function of C. These observations are interpreted as the result of the ion electrostatic self-energy barrier originating from the large difference in the dielectric constants of water and the lipid bilayer. The dependence of DNA capture rate on C also agrees with our model.Comment: more experimental material is added. 4 pages, 7 figure

Numerical estimation of Carbonate properties using a digital rock physics workflow

Digital rock physics combines modern imaging with advanced numerical simulations to analyze the physical properties of rocks -- In this paper we suggest a special segmentation procedure which is applied to a carbonate rock from Switzerland -- Starting point is a CTscan of a specimen of Hauptmuschelkalk -- The first step applied to the raw image data is a nonlocal mean filter -- We then apply different thresholds to identify pores and solid phases -- Because we are aware of a nonneglectable amount of unresolved microporosity we also define intermediate phases -- Based on this segmentation determine porositydependent values for the pwave velocity and for the permeability -- The porosity measured in the laboratory is then used to compare our numerical data with experimental data -- We observe a good agreement -- Future work includes an analytic validation to the numerical results of the pwave velocity upper bound, employing different filters for the image segmentation and using data with higher resolutio

Multimodality local ablative therapy of 23 lung metastases with surgical resection and percutaneous cryoablation in a patient with Li-Fraumeni Syndrome: A case report

Patients with Li-Fraumeni syndrome (LFS) are prone to develop a variety of malignancies due to insufficient activity of the encoded tumor suppressor protein P53, including adrenocortical carcinoma, breast cancer, lung cancer, pancreatic cancer, and sarcoma. In the setting of LFS, local treatment options for lung metastases are limited to surgery and thermal ablation since radiotherapy and some systemic therapies predispose patients to additional future malignancies. We present the case of a 45-year-old woman with LFS with leiomyosarcoma metastases to both lungs who underwent bilateral wedge resections to treat a total of eight lung metastases followed by six percutaneous cryoablation sessions to treat 15 additional lung metastases over a period of 24 months. Our case demonstrates the option of multimodal local ablative therapies for lung metastases in patients with LFS, including percutaneous cryoablation