The Ensenada Center for Scientific Research and Higher Education is a public research center sponsored by the National Council for Science and Technology of Mexico in the city of Ensenada, Baja California, and specialized in Earth science, Oceanography and Applied Physics.Its facilities include eight buildings which house laboratories, classrooms, a specialized library, supercomputing equipment, connection to Internet 2, the oceanographic vessel Francisco de Ulloa, and valuable seismological and oceanographic instrumentation and a library that holds more than 40,000 volumes. Wikipedia.
Bartnicki-Garcia S.,CICESE |
Bartnicki-Garcia S.,University of California at Riverside
Nature Reviews Microbiology | Year: 2015
Midway through the twentieth century, the availability of new and improved optical and electronic microscopes facilitated rapid advances in the elucidation of the fine structure of fungal cells. In this Essay, I pay tribute to Manfred Girbardt (1919-1991) and Charles Bracker (1938-2012)-two individuals who, despite being separated by geography and the restrictions of the Cold War, both made equally fundamental discoveries in fungal cell ultrastructure and set high standards for specimen manipulation and image processing. © 2014 Macmillan Publishers Limited. All rights reserved.
Acary V.,French Institute for Research in Computer Science and Automation |
Brogliato B.,French Institute for Research in Computer Science and Automation |
IEEE Transactions on Automatic Control | Year: 2012
In this paper, a novel discrete-time implementation of sliding-mode control systems is proposed, which fully exploits the multivaluedness of the dynamics on the sliding surface. It is shown to guarantee a smooth stabilization on the discrete sliding surface in the disturbance-free case, hence avoiding the chattering effects due to the time-discretization. In addition, when a disturbance acts on the system, the controller attenuates the disturbance effects on the sliding surface by a factor $h$ (where $h$ is the sampling period). Most importantly, this holds even for large $h$. The controller is based on an implicit Euler method and is very easy to implement with projections on the interval [$-$1, 1] (or as the solution of a quadratic program). The zero-order-hold (ZOH) method is also investigated. First- and second-order perturbed systems (with a disturbance satisfying the matching condition) without and with dynamical disturbance compensation are analyzed, with classical and twisting sliding-mode controllers. © 2012 IEEE.
Journal of Volcanology and Geothermal Research | Year: 2013
Underlying many studies of volcano clustering is the implicit assumption that vent distribution can be studied by using kernels originally devised for distribution in plane surfaces. Nevertheless, an important change in topology in the volcanic context is related to the distortion that is introduced when attempting to represent features found on the surface of a sphere that are being projected into a plane. This work explores the extent to which different topologies of the kernel used to study the spatial distribution of vents can introduce significant changes in the obtained density functions. To this end, a planar (Gauss) and a spherical (Fisher) kernels are mutually compared. The role of the smoothing factor in these two kernels is also explored with some detail. The results indicate that the topology of the kernel is not extremely influential, and that either type of kernel can be used to characterize a plane or a spherical distribution with exactly the same detail (provided that a suitable smoothing factor is selected in each case). It is also shown that there is a limitation on the resolution of the Fisher kernel relative to the typical separation between data that can be accurately described, because data sets with separations lower than 500. km are considered as a single cluster using this method. In contrast, the Gauss kernel can provide adequate resolutions for vent distributions at a wider range of separations. In addition, this study also shows that the numerical value of the smoothing factor (or bandwidth) of both the Gauss and Fisher kernels has no unique nor direct relationship with the relevant separation among data. In order to establish the relevant distance, it is necessary to take into consideration the value of the respective smoothing factor together with a level of statistical significance at which the contributions to the probability density function will be analyzed. Based on such reference level, it is possible to create a hierarchy of clustering degrees that allows us to obtain significant information in a geologic (and particularly volcanic) context. To illustrate this aspect of the kernel method, two examples using volcanic fields along the Peninsula of Baja California and the American continent are reported. © 2013 Elsevier B.V.
Earth-Science Reviews | Year: 2014
Assessing the relative importance of various triggers of volcanic eruptions has been hampered because of the lack of a general model that allows a quantitative comparison in an unbiased form. In this paper the most important triggers of volcanic eruptions are examined using a general reference framework that visualizes volcanic eruptions as the final event on a chain of causality. Based on this general framework, a hierarchical classification of triggers is proposed. First and second order triggers are defined as processes capable to initiate the rupture of the walls of a magma reservoir, regardless of whether the tapped magma can reach the surface or not. Third order triggers are those taking place only after the rupture of the walls of a magma reservoir has occurred, but are important in determining whether the tapped magma actually reaches the surface. A fundamental trigger is defined as any first order trigger that also can provide enough energy to feed a volcanic eruption even in the absence of third order triggers. The assessment of the relative importance of triggers is done by considering the whole range of depths from which a volcanic eruption is likely to have been fed, including magma reservoirs located deeper than 150. km, even when these eruptions might be relatively uncommon in the geological record. © 2013 Elsevier B.V.
Mourino-Perez R.R.,CICESE |
Advances in Genetics | Year: 2013
Hyphae of the Ascomycota are tubular cells compartmentalized by perforated septa, whose central pore allows the flow of organelles and cytoplasm. While in plants and yeast septation leads to cell separation, in filamentous fungi the formation of crosswalls appears to have an architectural role, limits the extent of mechanical damage thus maintaining hyphal integrity, and also is of fundamental importance as part of cell differentiation. The increasing number of available fungal genome sequences, knockout mutants, versatile tools for protein tagging, and the continuous improvement of fluorescence microscopes have allowed scientists to analyze living cells and reveal the molecular and cellular basis of septation with unprecedented detail. This review summarizes the recent advances in septum ontogenesis in Neurospora crassa. A "septal actomyosin tangle" is the first indication of impending septation. It assembles prior to any visible evidence of plasma membrane inward growth, which occurs concomitantly with the formation and constriction of a contractile actomyosin ring and synthesis of the septum wall. One of the key questions in septum biogenesis is how the septation machinery is assembled to construct a centripetally growing crosswall. Most of the machinery utilized in apical cell wall growth can be expected at septation sites to ensure an organized arrival and supply of vesicles leading to the formation of a septum. Yet, the intrinsically different architecture of the septum may require a different organization and regulation of the wall-synthesizing machinery. © 2013 Elsevier Inc.
Riquelme M.,CICESE |
Current Opinion in Microbiology | Year: 2014
The Spitzenkörper (SPK) is a multicomponent pleomorphic structure found at hyphal apices. It is necessary to maintain hyphal growth and morphogenesis in numerous fungal species, including plant and human pathogens. At the turn of the 21st century extraordinary advances in protein tagging technology and live microscopy allowed uncovering the main molecular constituents of the SPK. Distinct layers of macrovesicles and microvesicles, each carrying different cell wall synthetic enzymes, along with the actin cytoskeleton and related proteins are some of the components that make up the SPK. One of the biggest current challenges is to decipher the functional relationship between the SPK components and macromolecular complexes, such as the polarisome and the exocyst, which partially co-localize within the hyphal dome. © 2014 Elsevier Ltd.
Journal of Fluid Mechanics | Year: 2010
In this paper, solutions of free, barotropic waves around axisymmetric seamounts are derived. Even though this type of oscillation has been studied before, we revisit this problem for two main reasons: (i) the linear, barotropic, shallow-water equations with a rigid lid are now solved with no further approximations, in contrast with previous studies; (ii) the solutions are applied to a wide family of seamounts with profiles proportional to exp(rs), with r being the radial distance from the centre of the mountain and s any positive real number. (Most previous works are restricted to the special case s = 2.) The resulting dispersion relation possesses a remarkable simplicity that reveals a number of wave characteristics, for instance, the discrete wave frequencies and the angular phase speed of the waves around the seamount are easily derived as a function of the seamount shape. By varying the shape parameter one can study trapped waves around flat-topped seamounts or guyots (s > 2) or sharp, cone-shaped topographies (s < 2). © 2010 Cambridge University Press.
Fungal Biology Reviews | Year: 2013
Filamentous ascomycetes form multinucleated hyphae that are compartmentalized by septa. In this review, the central events in the dynamics and regulation of septum assembly of two ascomycetous model organisms (. Aspergillus nidulans and Neurospora crassa) are discussed. It has been shown that septum formation has different stages that start with the accumulation of signals after the completion of mitosis, followed by the assembly of a " septal actomyosin tangle" prior to plasma membrane invagination, the formation and constriction of a contractile actomyosin ring that coincides with plasma membrane invagination and finishing with construction of the septum wall and supporting plasma membrane. The role of actin, actin-binding proteins, landmark proteins, septins, and chitin synthases in each stage of septation is compared between the two model organisms. Although the main mechanisms seem to be conserved, the timing of the different proteins regulating the initiation of septum development, the determination of the septation site (i.e. cell division plane) and the constriction of the contractile actomyosin ring (CAR) differs from one organism to the other. © 2013 The British Mycological Society.
Estuarine, Coastal and Shelf Science | Year: 2012
A three-dimensional numerical model is used to study seasonal connectivity in the Gulf of California. From the Eulerian velocity fields of the model, particle trajectories were calculated for the 12 months of the year using an advection/diffusion scheme. Connectivity was quantified for twelve Gulf provinces with different dynamic/circulation characteristics being defined by the Eulerian velocity field: strong or weak coastal currents, eddies, and areas of mixing and exchange. Retention occurred for 9-12 months of the year in the Upper Gulf, Eddy and Sonora regions of the northern Gulf because of the Gulf-wide eddy circulation, which implies high potential for the auto-recruitment of larvae in this province. High retention was also found on the peninsula side of the southern Gulf in association with weaker residual currents, again implying potential for self-recruitment. In contrast, low retention was observed on the mainland side of the central and southern Gulf, from which particles are exported to many areas by the faster residual currents enhancing the potential for recruitment of distant coastal species. Empirical Orthogonal Function analyses revealed a strong annual and semiannual evolution in accordance with the strong seasonality of the Gulf dynamics. © 2012 Elsevier Ltd.
Cicese | Date: 2013-02-21
The invention relates to an isolated or recombinant protein from the shark Heterodontus francisci, which has bovine-erythrocyte-recognition activity and which can bind to sequences of antigens and/or proteins that are characteristic of infectious diseases. Once the aforementioned protein is bound to specific antigens of infectious diseases, it can haemagglutinate upon recognizing the bovine erythrocytes and antibodies characteristic of said diseases, which are present in the active state in biological samples such as whole blood, plasma or serum of bovine origin. The invention also relates to methods for protecting the detection of antibodies characteristic of infectious diseases, using the purified periplasmic extract or fusion protein, optionally purifying the recombinant protein.