Guidance on individual monitoring programmes for radioisotopic techniques in molecular and cellular biology

The radioisotope techniques used in molecular and cellular biology involve external and internal irradiation risk. The personal dosemeter may be a reasonable indicator for external irradiation. However, it is necessary to control the possible internal contamination associated with the development of these techniques. The aim of this project is to analyse the most usual techniques and to establish programmes of internal monitoring for specific radionuclides (32P, 35S, 14C, 3H, 125I and 131I). To elaborate these programmes it was necessary to analyse the radioisotope techniques. Two models have been applied (NRPB and IAEA) to the more significant techniques, according to the physical and chemical nature of the radionuclides, their potential importance in occupational exposure and the possible injury to the genetic material of the cell. The results allowed the identification of the techniques with possible risk of internal contamination. It was necessary to identify groups of workers that require individual monitoring. The risk groups have been established among the professionals exposed, according to different parameters: the general characteristics of receptor, the radionuclides used (the same user can work with one, two or three radionuclides at the same time) and the results of the models applied. Also a control group was established. The study of possible intakes in these groups has been made by urinalysis and whole-body counter. The theoretical results are coherent with the experimental results. They have allowed guidance to individual monitoring to be proposed. Basically, the document shows: (1) the analysis of the radiosotopic techniques, taking into account the special containment equipment; (2) the establishment of the need of individual monitoring; and (3) the required frequency of measurements in a routine programme.     

LaCOLLA: Middleware for Self-Sufficient Online Collaboration

The LaCOLLA middleware makes it possible for collaborators to interact using their own resources without depending on centralized regimes. By contributing their own resources, group members can organize and communicate using a federated peer-to-peer model. This lets the group function regardless of whether a member removes resources and despite network or node failures or disconnection. In turn, this capacity for self-organization, together with location transparency, lets application developers create self-sufficient applications for collaborative activity     

Mexican American middle school students' goal intentions in mathematics and science: A test of social cognitive career theory.

This study examined whether sociocontextual and sociocognitive variables explained the math/science goals of 409 Mexican American youth using a modified version of R. W. Lent, S. D. Brown, and G. Hackett's (1994) social cognitive career theory. Results from structural equation modeling indicated that the hypothesized model explained a significant amount of variance in math/science goals for both Mexican American girls and boys. Findings suggested that gender did not moderate relations among the variables in the hypothesized model. Results also suggested that most of the social cognitive career theory propositions tested were supported. Specifically, social class predicted math/science past performance accomplishments. Math/science past performance accomplishments and perceived parent support predicted math/science self-efficacy. Furthermore, math/science self-efficacy predicted math/science outcome expectations, and together with math/science interests, these sociocognitive variables predicted math/science interests and goals. Contrary to expectations, generation status, Anglo orientation, and Mexican orientation did not predict math/science past performance accomplishments, and past performance accomplishments did not predict math/science outcome expectations. Furthermore, Anglo orientation and perceived social support from parents, teachers, classmates, and a close friend did not predict math/science goals. Suggestions for future research and implications of the results are discussed. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Analysis of a sparse hypermatrix Cholesky with fixed-sized blocking

We present the way in which we have constructed an implementation of a sparse Cholesky factorization based on a hypermatrix data structure. This data structure is a storage scheme which produces a recursive 2D partitioning of a sparse matrix. It can be useful on some large sparse matrices. Subblocks are stored as dense matrices. Thus, efficient BLAS3 routines can be used. However, since we are dealing with sparse matrices some zeros may be stored in those dense blocks. The overhead introduced by the operations on zeros can become large and considerably degrade performance. We present the ways in which we deal with this overhead. Using matrices from different areas (Interior Point Methods of linear programming and Finite Element Methods), we evaluate our sequential in-core hypermatrix sparse Cholesky implementation. We compare its performance with several other codes and analyze the results. In spite of using a simple fixed-size partitioning of the matrix our code obtains competitive performance. This work was supported by the Ministerio de Educación y Ciencia of Spain (TIN2004-07739-C02-01).     

Fire severity assessment by using NBR (Normalized Burn Ratio) and NDVI (Normalized Difference Vegetation Index) derived from LANDSAT TM/ETM images

In this work, the capacity of NBR and NDVI indices derived from LANDSAT TM/ETM images has been analysed for fire severity assessment. For this purpose, three fires occurring in southern Spain were studied. Firstly, the displacements of burned and unburned pixels in the pre‐/post‐fire NIR‐MIR and NIR‐R bi‐spectral spaces were analysed with the aim of establishing which of the two indices was the most sensitive for discriminating severity levels. Then, the capacity of the two indices, both from a uni‐temporal (post‐fire) and bi‐temporal perspective (pre and post‐fire), to discriminate three severity levels was studied. Based on the results, it was decided that the most suitable way to assess wildfire severity by index segmentation was to discriminate between unburned and burned pixels according to their NBR pre‐/post‐fire difference values (dNBR), and, subsequently, to distinguish between pixels with an extreme and moderate severity based on the NBR post‐fire values. The thresholds calculated for these indices permitted fire severity mapping with an accuracy of 86.42% (±4.31%). These thresholds could be extrapolated to other fires with similar characteristics although a calculation of their own specific thresholds could improve the accuracy of the fire severity map obtained.     

Thermo-mechanical properties and microstructural considerations of MDI isocyanate-based bituminous foams

Stable bituminous foams have been obtained by using a 35/50 penetration grade bitumen and a reactive prepolymer (MDI-PPG) synthesized by the reaction of polymeric 4,4′-diphenylmethane diisocyanate (MDI) with a low molecular weight polypropylene glycol (PPG). In a first step, MDI-PPG and bitumen were allowed to react for up to 7 days. Foams were then obtained by adding an excess of water. The results obtained point out important changes in the material colloidal structure, as a consequence of the reactions between the –NCO groups and bitumen most polar fractions. Modification led to bituminous foams with low density and improved in-service properties (higher elasticity and resistance to deformation at high in-service temperatures, reduced thermal susceptibility and better flexibility at low temperatures), demonstrating their adequacy to be used in building applications. Properties were enhanced by subjecting the material to longer periods of curing prior to promote foaming.     

Fixed Queries Array: A Fast and Economical Data Structure for Proximity Searching

Pivot-based algorithms are effective tools for proximity searching in metric spaces. They allow trading space overhead for number of distance evaluations performed at query time. With additional search structures (that pose extra space overhead) they can also reduce the amount of side computations. We introduce a new data structure, the Fixed Queries Array (FQA), whose novelties are (1) it permits sublinear extra CPU time without any extra data structure; (2) it permits trading number of pivots for their precision so as to make better use of the available memory. We show experimentally that the FQA is an efficient tool to search in metric spaces and that it compares favorably against other state of the art approaches. Its simplicity converts it into a simple yet effective tool for practitioners seeking for a black-box method to plug in their applications.     

建立精密的直流浮动电流源

尽管有源滤波器的理论家和设计者都对GIC（通用阻抗变换器）非常熟悉，但一般模拟人员对它并不了解。一个单端口有源电路一般包括低成本运放、电阻和电容，GIC将容抗转换为感抗，因而可以替代滤波器中以RLC传输函数描述的电感。另外，GIC输入阻抗方程的灵活性允许进行虚拟阻抗的设计，这在实际元器件中是不存在的，例如依赖频率的电阻。GIC是30年前推出的，已广泛应用于交流电路和有源滤波电路。     

Structural and photoresponsive behavior of a series of (phenylene)azobenzene‐containing liquid‐crystalline methacrylic copolymers

A series of side‐chain liquid‐crystalline methacrylic copolymers, having various amounts of 4′‐(4‐decyloxyphenyl)‐4‐(hexyloxy)‐azobenzene as the mesogenic group, were synthesized and characterized by differential scanning calorimetry, polarizing optical microscopy and X‐ray diffraction to determine their mesomorphic properties, and by UV?visible spectrometry to elucidate their optical absorption characteristics. Also, birefringence and surface relief gratings were photoinduced in the films using a laser beam of 413 nm. Copolymers with high mesogen contents display a polymorphic behavior of the smectic type. The smectic order tends to disappear as the content of mesogens in the copolymer decreases, going from extended lamellar domains of chromophores packed in a parallel position, typical for smectic liquid crystals, to small aggregates of chromophores dispersed in an amorphous matrix. Important hypsochromic shifts (Δλ_max ≈ 20 nm), associated with π interactions between neighboring aromatic groups, confirm the aggregation of chromophores in lamellar structures. The light‐induced birefringence (0.005 ? 0.06) is not as high as expected but it corroborates that there exists a tight interplay between photoinduced orientation and intrinsic molecular order. Surface relief gratings were recorded in copolymers with low mesogen content (15 ? 30 mol%), showing by atomic force microscopy sinusoidal profiles with an average depth of around 150 nm. © 2013 Society of Chemical Industry     

Metabolic flux analysis of the hydrogen production potential in Synechocystis sp. PCC6803

Hydrogen is a promising energy vector; however, finding methods to produce it from renewable sources is essential to allow its wide-scale use. In that line, biological hydrogen production, although it is considered as a possible alternative, requires substantial improvements to overcome its present low yields. In that direction, genetic manipulation probably will play a central role and from that point of view metabolic flux analysis (MFA) constitutes an important tool to guide a priori most suitable genetic modifications oriented to a hydrogen yield increase.In this work MFA has been applied to analyze hydrogen photoproduction of Synechocystis sp. PCC6803. Flux analysis was carried out based on literature data and several basic fluxes were estimated in different growing conditions of the system. From this analysis, an upper limit for hydrogen photoproduction has been determined indicating a wide margin for improvement. MFA was also used to find a feasible operating space for hydrogen production, which avoids oxygen inhibition, one of the most important limitations to make hydrogen production cost effective. In addition, a set of biotechnological strategies are proposed that would be consistent with the performed mathematical analysis.