1,721,034 research outputs found
A DIFFERENT INTRACELLULAR DISTRIBUTION OF A SINGLE REPORTER PROTEIN IS DETERMINED AT STEADY STATE BY KKXX RETRIEVAL SIGNALS.
No full textTo establish the specific contribution to protein topology of KKXX and KDEL retrieval motifs, we have determined by immunogold electron microscopy and cell fractionation the intracellular distribution at steady state of the transmembrane and anchorless versions of human CD8 protein, tagged with KKXX (CD8-E19) and KDEL (CD8-K), respectively, and stably expressed in epithelial rat cells (Martire, G,, Mottola, G., Pascale, M. C., Malagolini, N., Turrini, I., Serafini-Cessi, F,, Jackson, M, R., and Bonatti, S, (1996) J. Biol. Chem. 271, 3541-3547). The CD8-E19 protein is represented by a single form, initially O-glycosylated: only about half of it is located in the endoplasmic reticulum, whereas more than 30% of the total is present in the intermediate compartment and cis-Golgi complex. In the latter compartments, CD8-E19 colocalizes with beta-coat protein (COP) (COPI component) and shows the higher density of labeling. Conversely, about 90% of the total CD8-KDEL protein is localized in clusters on the endoplasmic reticulum, where significant co-localization with Sec-23p (COPII component) is observed, and unglycosylated and initially O-glycosylated forms apparently constitute a single pool. Altogether, these results suggest that KKXX and KDEL retrieval motifs have different topological effects on theirs own at steady state: the first results in a specific enrichment in the intermediate compartment and cis-Golgi complex, and the latter dictates residency in the endoplasmic reticulum
A Novel Spatial 3-DoF Constant-Force Generator for the Static Balancing of Parallel Robots
No full textA statically-balanced mechanism can remain in indifferent equilibrium at a continuous set of poses while the actuators exert zero work, as the links’ weight is resisted by conservative balancing forces. This can be achieved, for example, by adding counterweights or springs. Studies on gravity balancing frequently target parallel robots, to increase their intrinsic advantages of high stiffness and smaller motor size. Here, it is considered how to balance a 3-DoF kinematic chain for applications on parallel robots, such that the chain generates a constant force on the end-effector. The design does not include counterweights and has most of the auxiliary balancing elements on the fixed base, thus reducing the inertia of moving elements; the motion is transmitted through a lightweight system of gears, pulleys and synchronous belts. The design also leaves greater freedom in the selection of the spring, which (unlike most previous works) may have nonzero free length
Nomograms: An Old Tool with New Applications
No full textIn this paper, we consider the history of nomograms as a computational tool in mechanical engineering, together with their potential applications for teaching purposes, and summarize the mathematical methods used to derive them. Nomograms are graphical descriptions of a mathematical problem, such that the desired solution may be derived through a simple geometric construction, which usually requires nothing more than a straightedge. This way, a reasonably accurate solution to a complex problem can be quickly obtained even in adverse environmental conditions by low-skilled users; moreover, a nomogram can provide immediate insight on the relationship between the variables. Nomograms date back to the 1800s and have been used by engineers for decades, due to their convenience over manual computation, before computers became widespread. While nomograms have now been largely superseded as engineering tools, our analysis shows that they can still have some applications in workshops and for teaching purposes
Qualità del siero del caseificio a pasta filata e soluzioni impiantistica di recupero
No full textThis paper refers to a three year research carried out, on 100 Apulian dairy industries, to evaluate the chemical and physical characteristics of the acid whey produced using the "Pasta filata" method.
This whey, usually, represents about the 85% of the raw milk and, after threading, his characteristics get worse and worse because of the particular adopted dairy systems and the used removing and storing plants which are not able to preserve the by-products quality from the waste water.
At last, the study gives the main problems, which it has been to solve, and the suitable technologies to make a correct recovering of the whey coming from this particular dairy process. It is important to underline that the recovering process has to be planned also considering the Italian laws and the situation of the “Pasta filata” dairy industries in the Southern Italy
Dynamic Launch Trajectory Planning of a Cable-Suspended Translational Parallel Robot Using Point-to-Point Motions
Full text linkIn the last decade, cable-suspended parallel robots have attracted significant interest due to their large workspaces and high dynamic performances. However, a significant drawback is that cables must always be in tension to control the motion. Using launch motions to reach a target can enlarge the workspace of such robots. For a spatial translational cable robot suspended by six pairwise-parallel cables, an analytical method for planning point-to-point dynamic trajectories is proposed. Using a second-order Bézier curve trajectory, the mechanism starts from a static condition, passes through intermediate points, and finally launches an object towards a target. According to the kinematic constraint conditions on the position, the velocity and acceleration of the end-effector at a prescribed point, the parametric expressions for a dynamically-feasible trajectory can be determined. The feasibility of the trajectory is analyzed under the constraint that cable tensions must be positive at all times. By changing the position of the end point of the trajectory and the total motion time, the kinematic conditions on the position and velocity as well as the feasibility constraint can be satisfied. Finally, our point-to-point dynamic launch trajectories are verified by simulations and experiments
Modeling and control of a cable-suspended sling-like parallel robot for throwing operations†
Full text linkCable-driven parallel robots can provide interesting advantages over conventional robots with rigid links; in particular, robots with a cable-suspended architecture can have very large workspaces. Recent research has shown that dynamic trajectories allow the robot to further increase its workspace by taking advantage of inertial effects. In our work, we consider a three-degrees-of-freedom parallel robot suspended by three cables, with a point-mass end-effector. This model was considered in previous works to analyze the conditions for dynamical feasibility of a trajectory. Here, we enhance the robot’s capabilities by using it as a sling, that is, by throwing a mass at a suitable time. The mass is carried at the end-effector by a gripper, which releases the mass so that it can reach a given target point. Mathematical models are presented that provide guidelines for planning the trajectory. Moreover, results are shown from simulations that include the effect of cable elasticity. Finally, suggestions are offered regarding how such a trajectory can be optimized
Going Beyond Counting First Authors in Author Co-citation Analysis
Full text linkThe present study examines one of the fundamental aspects of author co-citation analysis (ACA) - the way co-citation
counts are defined. Co-citation counting provides the data on which all subsequent statistical analyses and mappings
are based, and we compare ACA results based on two different types of co-citation counting - the traditional type that
only counts the first one among a cited work's authors on the one hand and a non-traditional type that takes into
account the first 5 authors of a cited work on the other hand. Results indicate that the picture produced through this non-traditional author co-citation counting contains more coherent author groups and is therefore considerably clearer. However, this picture represents fewer specialties in the research field being studied than that produced through the traditional first-author co-citation counting when the same number of top-ranked authors is selected and analyzed. Reasons for these effects are discussed
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