N-body U and K matrix program

Computer program was devised to compute free-fall trajectories of satellites, allowing for injection errors and midcourse velocity perturbations. Program consists of trajectory perturbing program and N-body integrating conic program which can also be used as 2-body patch conic program

The effect of Six Sigma on corporate performance in the manufacturing and service sectors

As global competition becomes more intense, organizations try to implement strategies that allow them become more efficient, increase quality and productivity, and stay ahead of their competition. Over the years, there have been different programs or methodologies that companies have adopted with the purpose of achieving enhanced operational performance and bottom line impact. Six Sigma is one of the strategies that have gained more popularity during recent years, being adopted by companies in both manufacturing and service. There have been numerous claims by adopting companies about the financial benefits of implementing Six Sigma. However, the number of studies conducting empirical research to back those claims is limited. ^ The purpose of this study was to evaluate whether Six Sigma impacts corporate performance and the extent to which that impact is similar for manufacturing and service companies. The study was conducted by selecting a sample of 48 companies, within the manufacturing and service sectors, and assessing the effect of Six Sigma adoption by comparing their financial performance with the performance of control companies that did not implement Sig Sigma, during a period of 8 years after implementation. The statistical results provided evidence to conclude that Six Sigma has a positive effect on financial performance in the long term, showing significant results for years 7 and 8 after implementation, with the sample companies outperforming their corresponding control companies for these periods of time. The results were consistent in both manufacturing and service for year 8, validating that the impact of Six Sigma is similar for both sectors

Bilayer graphene under pressure: Electron-hole Symmetry Breaking, Valley Hall Effect, and Landau Levels

The electronic structure of bilayer graphene under pressure develops very interesting features with an enhancement of the trigonal warping and a splitting of the parabolic touching bands at the K point of the reciprocal space into four Dirac cones, one at K and three along the T symmetry lines. As pressure is increased, these cones separate in reciprocal space and in energy, breaking the electron-hole symmetry. Due to their energy separation, their opposite Berry curvature can be observed in valley Hall effect experiments and in the structure of the Landau levels. Based on the electronic structure obtained by Density Functional Theory, we develop a low energy Hamiltonian that describes the effects of pressure on measurable quantities such as the Hall conductivity and the Landau levels of the system.Comment: 11 pages, 9 figure

The morphodynamic responses of artificial embayed beaches to storm events

The morphological changes caused by storm events in two Barcelona beaches were recorded using video monitoring techniques during the period 2001–2006. Changes in shoreline position and configuration and submerged bar position and shape were analyzed during the 25 major storm events that occurred during the study period. Beach responses to storms were grouped into three categories: shoreline advance or retreat (including rotation), sandbar migration and/or configuration change (linear or crescentic shape) and formation of megacusps. This work provides examples of the differential adaptation of both beaches to the same storm and of some unexpected morphological responses of both beaches. The response of the beach to storm events is not straightforward because wave conditions are not the only relevant parameter to be considered. In particular, in such embayed beaches it is crucial to take into account their specific morphodynamic configuration prior to the storm

Influence of water status on mineral composition of berries in ‘Grenache Noir’ (Vitis vinifera L.)

The influence of vine water status on the seasonal changes of fresh weight, dry matter and the levels of potassium and calcium in grape-berries on field vines of 'Grenache Noir' (Vitis vinifera L.), was studied over a two-year period. Two levels of water status, irrigated and non-irrigated, were investigated using a single level of total leaf surface – each primary shoot was confined to ten leaves, one grape bunch, and the secondary shoots were removed as they appeared. The mineral element contents were determined separately in different fruit compartments, i.e. the skin, flesh and seeds. Potassium and calcium accumulate independently of one another, but their seasonal change in the fruit and their final quantities in the berry depend principally on plant water status. The accumulation of potassium parallels the change in fruit fresh weight; approximately 50 % of the final content was accumulated pre-veraison and loading continued during berry ripening. This report shows that a small quantity of calcium may accumulate throughout fruit ripening phases in situations where water supply is not a limiting factor. These results imply that fruit xylem is functioning partially during ripening. Moreover, in both water status situations, the quantity of calcium in the skin increases during ripening, which suggests apoplastic and/or symplastic migration in the berry.

Leaf:Fruit Ratio and Vine Water Status Effects on Grenache Noir (Vitis vinifera L.) Berry Composition: Water, Sugar, Organic Acids and Cations

Seasonal variation in the water, sugar, organic acid and cation contents of developing grape berries (Vitis viniferaL. ‘Grenache noir’) under different levels of water supply (with and without deficit irrigation) and leaf:fruit ratios(18, 10 and five leaves per primary shoot, with one bunch per shoot), were investigated over two successive years inMediterranean conditions (South of France). Fourteen shoots per vine were left for each leaf:fruit ratio level, andeach vine was considered as having homogeneous primary shoots. The growth rate of the berries was increased withirrigation. Total dry matter content of the berry was not affected by leaf:fruit ratios, but the sugar loading decreasedduring berry development with a lower leaf:fruit ratio (five leaves per bunch). Treatments had little effect on organicacid contents and pH. Berry cation accumulation depended on vine water status and not on the total leaf area ofthe vine. Under irrigated conditions, calcium continued to accumulate in the berries after véraison. This confirms apartial functioning of the berry xylem during the post-véraison period. The seasonal variation in berry compositionwas less dependent on the leaf:fruit ratio than on the water status of the vine (mainly cations and sugar). This studyprovides evidence for the importance of plant water status effects on berry composition, irrespective of the leaf:fruitratio. Vine water status is a major regulating factor for source-sink relationships

Radiation Induced Membrane Changes and Programmed Cell Death: Possible Interrelationships

A short review of the evidence that lymphocyte membranes are a target for the initiation of irradiation induced programmed cell death (PCD) is given. It is assumed that for lymphocytes PCD represents an essential physiological mechanism in order to prevent degeneration of the biological system involved. Initiation of PCD can be obtained by a pharmacological activation as well as with irradiation. In both cases, protein kinase-C (PKC) is involved in the signal transduction from the cellular membrane to the nucleus where, by means of a metabolically active process, DNA fragmentation is induced. It is hypothesized that processes connected to lipid peroxidation in the cell membrane constitute a primary effect of irradiation induced PCD, where membrane fluidization or a compensatory process aimed to the maintenance of membrane fluidity (membrane homeoviscosity hypothesis) are likely to be involved

Prótesis de rodilla externa mecatrónica

Se diseña un mecanismo de articulación de rodilla para una prótesis externa, es decir el prototipo puede ser usado en personas con amputaciones del tipo transfemoral, con el fin de contribuir a la sociedad al brindar soluciones a favor de las personas con capacidades especiales. Se toma en consideración los aspectos más relevantes para el desarrollo de la marcha humana protésica normal como son: nivel de actividad física, medidas antropométricas, materiales adecuados para la construcción, estabilidad y confort entre otros. Luego de realizar un análisis extensivo y proceso de diseño y rediseño se construyó un prototipo funcional, que en el futuro podrá ser probado en personas que así lo requieran.Peer Reviewe

Professor Buenaventura Delgado Bujalance. Looks and creative teaching

El profesor Buenaventura Delgado Bujalance desarrolló hasta su muerte una dilatada y creativa actividad como geógrafo. De ella, a modo de homenaje y reconocimiento, queremos destacar en este artículo, por una parte, su convicción de la validez del viaje como fuente de conocimiento, sustentado en la sorpresa, el atrevimiento o la empatía. Por otra, el valor del cuaderno de campo como instrumento de comprensión y trasmisión del conocimiento adquirido y como herramienta de aprendizaje y evaluación. El texto plantea, pues, en primer lugar las bases conceptuales en las que Buenaventura apoya su actividad, para después analizar sus cuadernos de campo y terminar presentando algunos resultados de la propuesta didáctica a través del viaje que, junto a él, hemos ido realizando en los últimos años

Exploring the boundaries in the analysis of large particles by single particle inductively coupled plasma mass spectrometry: application to nanoclays

The analysis of microparticles by single particle inductively coupled plasma mass spectrometry (SP-ICP-MS) requires sample introduction systems that guarantee transport efficiencies similar to those obtained with dissolved standards across the size range covered. The utilization of a nebulisation system based on a linear pass spray chamber and a micronebuliser is discussed and optimized for the introduction of large inorganic particles. Limitations caused by incomplete ionisation or the counting limit of detectors affecting particle size characterisation are also considered. The procedure developed has been applied to the characterisation of suspensions of a natural clay (kaolinite), with a thickness in the range of a few nanometers and lateral dimensions up to 1 mu m. The application of different sensitivity conditions by the modification of the ion transmission allowed us to cover the whole size range of the suspension monitoring the Al-27 isotope and achieve a quantitative mass recovery with respect to ICP-MS analysis. Finally, the migration of nanoclays (montmorillonite) from food containers and their detection by SP-ICP-MS are presented. The results have been compared to those obtained by TEM, showing that nanoclays migrated from the containers into water