Effects of drawing conditions on the properties of optical fibers made from polystyrene and poly(methyl methacrylate)

Monofilaments possessing various degrees of birefringence were obtained by changing the drawing rate, the molten polymer temperature, and the molecular weight of polystyrene (PS) and poly(methyl methacrylate) (PMMA). The “brittle-toductile” transition point of optically pure PS was found in the range of birefringences of ?0.6 · 10^?3 to ?2.6 · 10^?3. Both the height and position of this point are influenced by M?_w, molecular weight distribution, and polymer melt temperature. The birefringence of PS is higher by two orders of magnitude than that of PMMA in which this transition point has not been observed. The mechanical and optical properties depend not only on the average amount of orientation characterized by the birefringence but on what portion of the relaxation spectrum of the polymer is preferentially oriented. During the drawing of PS and PMMA monofilaments crazes are formed in the centre of the fibers and do not reach the surface.     

Proteolytic activity and immunoreactivity of chemically modified Papain

Summary The effect of different chemical modifications of papain on the proteolytic activity and immunoreactivity has been studied. Modification with Dextran T 2000 caused increasing decline in proteolytic activity both with increasing degree of dextran oxidation and amount of bound dextran, whilst the immunoreactivity determined by nephelometry remained unchanged. Modification of papain with glutaraldehyde and formaldehyde causes rapid drops in both activities, even at very low concentrations of agents. Acetylation of papain showed expressive maxima of both proteolytic and immunochemical activities at the same degree of enzyme acetylation. Modification with diazobenzensulphonic acid caused a high increase in immunoreactivity and a small increase in proteolytic activity.

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Proteolytische Aktivität und Immunreaktivität von chemisch modifiziertem Papain

Zusammenfassung Es wurde der Einfluß verschiedener chemischer Modifizierung des Papains auf dessen proteolytische Aktivität und Immunreaktivität untersucht. Die Modifikation des Papains mit Dextran T 2000 1äßt die proteolytische Aktivität bei steigender Dextran-oxidation und mit der Menge des gebundenen Dextrans abnehmen, wobei die Immunreaktivität, nephelometrisch bestimmt, unverändert bleibt. Bei der Modifizierung von Papain mit Glutaraldehyd und Formaldehyd werden beide Aktivitäten, auch bei sehr niedrigen Konzentrationen der Reagentien, stark erniedrigt. Das acetylierte Papain zeigt ein scharfes Maximum der proteolytischen und der immunchemischen Aktivität bei demselben Grad der Enzymacetylierung. Die Modifizierung von Papain mit der Diazobenzosulfonsäure verursacht einen hohen Anstieg der Immunreaktivität und einen nur geringen der proteolytischen Aktivität.

     

Plastic dilution refrigerators

A new design for conventional,³He re-circulating, dilution refrigerators has been developed and tested. The units are made out of plastic and can be designed to have very small diameters (<15mm). These characteristics make them ideal to cool samples below 100 mK in high or time-varying magnetic fields. Furthermore, they are inexpensive, reliable and easily constructed. The best refrigerators reach continuous temperatures of around 10 mK at low circulation rates ( 100 mol/s). The cooling power at high temperatures is limited by the speed of the circulation pump and not by the refrigerator itself. The basic design and construction methods are discussed.     

Distribution-insensitive cluster analysis in SAS on real-time PCR gene expression data of steadily expressed genes

Cluster analysis is a tool often employed in the micro-array techniques but used less in the real-time PCR. Herein we present core SAS code that instead of the Euclidian distances takes correlation coefficient as a dissimilarity measure. The dissimilarity measure is made robust using a rank-order correlation coefficient rather than a parametric one. There is no need for an overall probability adjustment like in scoring methods based on repeated pair-wise comparisons. The rank-order correlation matrix gives a good base for the clustering procedure of gene expression data obtained by real-time RT-PCR as it disregards the different expression levels. Associated with each cluster is a linear combination of the variables in the cluster, which is the first principal component. Large set of variables can then be replaced by the set of cluster components with little loss of information. In this way, distinct clusters containing unregulated housekeeping genes along with other steadily expressed genes can be disclosed and utilized for standardization purposes. Simulated data in parallel with the data from a biological experiment were taken to validate the SAS macro. For both cases, good intuitive results were obtained.     

Locally Injective Mappings

Mappings and deformations are ubiquitous in geometry processing, shape modeling, and animation. Numerous deformation energies have been proposed to tackle problems like mesh parameterization and volumetric deformations. We present an algorithm that modifies any deformation energy to guarantee a locally injective mapping, i.e., without inverted elements. Our formulation can be used to compute continuous planar or volumetric piecewise‐linear maps and it uses a barrier term to prevent inverted elements. Differently from previous methods, we carefully design both the barrier term and the associated numerical techniques to be able to provide immediate feedback to the user, enabling interactive manipulation of inversion‐free mappings. Stress tests show that our method robustly handles extreme deformations where previous techniques converge very slowly or even fail. We demonstrate that enforcing local injectivity increases fidelity of the results in applications such as shape deformation and parameterization.     

Adaptable Anatomical Models for Realistic Bone Motion Reconstruction

We present a system to reconstruct subject‐specific anatomy models while relying only on exterior measurements represented by point clouds. Our model combines geometry, kinematics, and skin deformations (skinning). This joint model can be adapted to different individuals without breaking its functionality, i.e., the bones and the skin remain well‐articulated after the adaptation. We propose an optimization algorithm which learns the subject‐specific (anthropometric) parameters from input point clouds captured using commodity depth cameras. The resulting personalized models can be used to reconstruct motion of human subjects. We validate our approach for upper and lower limbs, using both synthetic data and recordings of three different human subjects. Our reconstructed bone motion is comparable to results obtained by optical motion capture (Vicon) combined with anatomically‐based inverse kinematics (OpenSIM). We demonstrate that our adapted models better preserve the joint structure than previous methods such as OpenSIM or Anatomy Transfer.     

Application of the advanced radon diagnosis methods in the indoor building environment

The health risk and dose calculations from exposure to indoor radon and its decay products are generally based on long-term integral measurements and standard ICRP recommendations. In this context, the results of assessments predicate more about human activities inside the building instead of a quality and an effectiveness of applied measures against the radon. The present paper is focused on a set of different measuring techniques and methods practically used for a classification of buildings regarding to the radon protection requirements. The fundamental quantitative and qualitative procedures of radon transport pathways and radon sources analysis, commonly named as radon diagnostic methods are performed in detail.     

Neutron and photon fields in the BNCT room with closed beam shutters

The epithermal neutron beam at the LVR-15 reactor was designed for the Boron Neutron Capture Therapy (BNCT) of cancers, but it has also been used for material testing. In the case where the beam is closed with two designed shutters, there is still an indispensable background in the irradiation room, which limits the movement of persons during patient positioning before exposure or during the preparation of the samples. Because the epithermal filter of the beam was designed in a former thermal column, as a multi-layer system, it was suspected that both fast neutrons and photons penetrated the filter shielding into the room. The purpose of this study was to determine the causes of potential faulty shielding and to estimate the doses to persons who perform the irradiation experiments and/or exposure of patients. The quality of the shielding was evaluated from two-dimensional measurements of both neutron and photon distribution on the surface of the beam shutter. During the measurement both the shutters of the epithermal beam were closed and the reactor was operated at the nominal power of 9 MW. This experimental arrangement is similar to the conditions that exist when either the irradiation experiments or the exposure of patients is performed in this room. The neutron space distribution was measured using a Bonner sphere of phi 76.2 mm diameter with an LiI(TI) scintillation detector of phi 4 x 8 mm. A small Geiger-Muller tube was used for the measurement of photon distribution. The detectors were placed on a three-dimensional positioning equipment controlled by a computer, which enabled automatic measurement with 1 cm mesh step. Results of the measurement show that the background profile in the irradiation room has reasonable maximum only at the beam aperture.     

Fast and Robust Inversion‐Free Shape Manipulation

We present a shape manipulation technique capable of producing deformations of 2D and 3D meshes, guaranteeing that no elements will be inverted. We achieve this by augmenting the quadratic ex‐rotated elastic energy with additional convex terms that penalize the presence of inverted elements. Using a schedule of increasing penalty coefficients, we efficiently and robustly converge to an inversion free state by solving a sequence of unconstrained convex minimization problems. This process can be interpreted as a special purpose Semi‐Definite Programming (SDP) solver. We demonstrate that our method outperforms solvers used in previous work, including commercial‐grade SDP software (MOSEK). As an additional benefit, our method also converges to the solution via a more intuitive path, which can be used for quick preview. We demonstrate the efficacy of our scheme in a number of 2D and 3D shapes undergoing moderate to drastic deformation.