31 research outputs found
Hydrolagus mccoskeri
No full textHydrolagus mccoskeri - 1 specimen. CAS 86558, juvenile female, 381 mm TL, 274 mm PCL, 211 mm BDL, southeast of San Cristobal Island, Galapagos (01°5.981’S, 89°12.235’W), 396.24 m, collected by J.E. McCosker (CAS), R. Grant Gilmore (HBOI) and Bruce Robison (MBARI), 17 Nov. 1995 (JSL dive 3934)Published as part of Kimberly L. Quaranta, Dominique A. Didier, Douglas J. Long & David A. Ebert, 2006, A new species of chimaeroid, Hydrolagus alphus sp. nov. (Chimaeriformes: Chimaeridae) from the Galapagos Islands., pp. 33-45 in Zootaxa 1377 on page 4
Hydrolagus
No full text[[Hydrolagus]] Key to the Eastern South Pacific species of Hydrolagus 1a. Light brown or tan coloration with numerous white markings on body.... H. mccoskeri 1b. Uniform dark brown coloration with few or no white markings on body................... 2 2a. Body with no white markings on lateral side; snout tip pointed; slight raise in anterior portion of second dorsal fin with shallow notch medially; eyes 33.8-39.3% HDL; tail region from insertion of pelvic fins to origin of dorsal caudal fin extremely long and slender (always> 60 % BDL)......................................................... H. macrophthalmus 2b. Body with one white spot on lateral side above pectoral fin or in abdominal region; snout tip blunt; anterior and posterior regions of second dorsal fin lobate with indented white middle region; eyes large (40.8-44.5% HDL); tail region from insertion of pelvic friends to origin of dorsal caudal fin short and stout (always <57 % BDL)...................................................................................................................................... H. alphusPublished as part of Kimberly L. Quaranta, Dominique A. Didier, Douglas J. Long & David A. Ebert, 2006, A new species of chimaeroid, Hydrolagus alphus sp. nov. (Chimaeriformes: Chimaeridae) from the Galapagos Islands., pp. 33-45 in Zootaxa 1377 on pages 42-4
Hydrolagus alphus Quaranta, Didier, Long & Ebert, 2006, sp. nov.
No full textHydrolagus alphus sp. nov. (Whitespot ghostshark) Figures 2, 3; Tables 1, 2 Holotype: CAS 201902, adult male, 419 mm TL, 249 mm BDL; Galapagos Islands, Ecuador, North end of Seymour Island (0°21'42"S, 90°15'0"W), 648 m, 25 July 1998, J. E. McCosker (CAS) and Carole Baldwin (USNM) by vacuum hose aboard the Johnson Sea Link II (JSL dive #3113). Paratype: CAS 86425, sub-adult female, 480 mm TL, 244 mm BDL, Galapagos Islands, Ecuador, Fernandina Island (0°14.641'S91°26.535'W -0°14.820'S91°26.410'W), 731.52 m, 17 Nov. 1995, J. E. McCosker (CAS), R. Grant Gilmore (HBOI) and Bruce Robison (MBARI) by vacuum hose aboard the Johnson Sea Link II (JSL dive #3958). Additional specimens observed but not collected: 26 November 1995, Galapagos Islands, Ecuador, Isla Santiago, James Bay, one specimen seen and photographed at a depth of 907 m (JSL dive #3977); 23 June 1998, Galapagos Islands, Ecuador, Isla Fernandina, Cabo Douglas, one specimen observed at a depth of 630 m (JSL dive #2900) and sketched by J.E. McCosker. Diagnosis. Assigned to the genus Hydrolagus based upon the absence of an anal fin. Hydrolagus alphus is distinguished by being medium in size (average PCL 321 mm) and uniform dark brown in color with a distinct white spot (4%-6% BDL) on the lateral side above the pectoral fins. Paired fins with bluish hue and white margins. The dorsal spine longer than triangular shaped first dorsal fin and extends beyond the origin of the second dorsal fin when depressed. Eyes large (40.8-44.5% HDL) and pectoral fins reaching to or beyond insertion of pelvic fins when depressed. Pelvic claspers small, not extending beyond distal edge of pelvic fin, and divided distally for one half their length with slender fleshy denticulate tips. The base of second dorsal fin is long, deeply depressed and light colored in the center, anterior and posterior regions dark, considerably greater in height than the white middle region. Description. Measurements and body proportions of the holotype and paratype are presented in Table 1. Small to medium sized species with stout trunk, uniform in height until insertion of pelvic fins, then quickly tapering posteriorly and extending to a thin caudal filament. Eyes large (40.8-44.5% HDL) and slightly oval in shape. Snout blunt, tip protruding slightly, squared off towards the mouth. First dorsal fin triangular and attached to the dorsal spine at or below midpoint. Both spine and fin depress into a groove situated on dorsal ridge. Dorsal spine longer than the dorsal fin, serrated along the anterior side from just below the distal tip to above the base. Posterior side of dorsal spine has two rows of long serrations extending from the tip to the midpoint. When the dorsal spine is depressed, the tip reaches beyond the origin of the second dorsal fin. Base of the second dorsal fin is long, extending from mid-body to caudal fin, anterior and posterior regions are dark colored with a small band of white coloration on the distal margins and distinctly lobed, with the middle region white, indented for 1/4 the length of second dorsal fin. Anterior portion is greater in height (7.2% BDL) then the posterior portion (4.4 % BDL) with the middle portion less than 2% BDL in height. Second dorsal fin is separated from the caudal fin by a membrane. Caudal fin consists of a rounded dorsal and ventral lobe, with the ventral lobe being slightly greater in height. The ventral portion of the caudal fin base is longer than the dorsal caudal fin base and has a fleshy membrane extending onto the posterior body region. Caudal fins are white distally around the margins. Anal fin absent. Pectoral fins are large (39.8% BDL) and triangular reaching just below the first dorsal fin when depressed dorsally and to the insertion of the pelvic fins when depressed horizontally. Posterior margin of pectoral fins are convex near base, progressing concavely to distal tip, anterior margin slightly convex. Pectorals moderately dark in color, preserved specimens have a purplish-blue hue on fins with a white border around the margins. Pelvic fins are large, oblong with convex margins. Coloration of pelvic fins in preservative is the same as pectoral fins. Oral and preopercular head canals extend ventrally sharing a common branch from the infraorbital canal. Trunk lateral line canal extends the length of the body until it reaches the caudal fin where it extends down ventrally onto the tail filament. Secondary sexual characteristics in males include a long frontal tenaculum (32.5 % HDL) moderately curved, ending in a bulbous tip with tenacular hooks starting below the dorsal surface and aligned vertically in rows with 6-8 denticles in each, getting larger ventrally, pre-pelvic tenacula with at least 4 hooks on the outer margin and pelvic claspers that are bifid, slender with wrinkled fleshy pads at tips and divided distally for one half of their length. Females with anal pads, not present in males. Color. Uniform chocolate brown when live, with superficial bluish sheen depending on angle of light. Areas around the opercular, rostral, predorsal, and abdominal regions may be slightly darker. Medial, pectoral, pelvic, and caudal fins are dark slate or blackish grey with a slight bluish hue, and all the fins have a narrow white band on the terminal edge. The low median area between the anterior and posterior sections of the second dorsal is entirely white. The first dorsal, pectoral and pelvic fins show a narrow blackish band on the posterior edge of the fins adjacent to the white terminal band. The dorsal axial area of the pectoral region is usually whitish, and specimens have one well-defined white spot on their lateral sides above the pectoral fin, sometimes one or more white spots not as welldefined may occur in the abdominal or anterior caudal regions also. The pigment around the outer margins of the eye is a blackish brown, and the tapetum lucidum reflects a celadon green. Coloration of the main body in preserved specimens is a uniform brown to dark brown, with white margins on the tips of the fins and a distinct white spot (4%-6% BDL) on the lateral side, mid-body above the pectoral fin. Second dorsal fin is dark anteriorly and posteriorly, center region distinctly white in color. Habitat. The adjacent substrate at sites of capture varied between slopes and ledges containing large volcanic boulders, cobbles, and gravels, frequently overlain by, or interspersed with, patches of sand and coarse silt. The rocky areas were completely devoid of algae, but often had sparse to dense encrustations of benthic invertebrates such as stony corals, sponges, crinoids, hydroids, gorgonians, and bryozoans. Holothurans and ophiuroids were also present. All four specimens of Hydrolagus alphus were caught or observed within three meters of the substrate. Etymology. The specific name, alphus (Latin, adj.), means white spot on the skin and is in reference to a key characteristic found in this species. Common name. We propose the English common name of “whitespot ghostshark” in keeping with the Latin translation and key characteristic. Interspecific Comparisons. There is at least one additional species that occurs within the Galapagos Islands region in addition to Hydrolagus alphus. A new Hydrolagus species, Hydrolagus mccoskeri, was discovered during the same surveys of the Galapagos Islands as in this study (Barnett et al., 2006). Hydrolagus mccoskeri is distinct from H. alphus in coloration and fin sizes. Most notably, H. mccoskeri contains numerous white markings on the body different than the single white spot found on H. alphus. The second dorsal fin is uniform in height in H. mccoskeri with a marginal rise in the anterior portion, whereas in H. alphus the anterior and posterior regions of the second dorsal fin are considerably taller than the middle region, with the middle region white in H. alphus. The pectoral and pelvic fins are smaller in H. mccoskeri. Distribution of the two species also differs. Hydrolagus alphus occurs in deep pre-abyssal waters (about 600-800 m), while H. mccoskeri occurs in more shallow waters, at depths of 400 m (Barnett et al., 2006). Hydrolagus alphus is distinct from Hydrolagus macrophthalmus, most notably in coloration and the appearance of a white spot on the lateral side. In addition, the size of the tail region from insertion of pelvic fins to origin of dorsal caudal fin, the structure (shape and size) of the second dorsal fin, eye length, snout morphology, lengths of lateral line canals in the head and secondary sexual characteristics also differ. Coloration of preserved Hydrolagus macrophthalmus is an even brown with no white markings or white coloration pattern. Hydrolagus alphus is also brown, but with a distinctive white spot found on the lateral side above the pectoral fin or abdominal region. The tail region from insertion of pelvic fins to origin of dorsal caudal fin in H. macrophthalmus is elongate and slender and always greater than 60% BDL. The tail region in H. alphus is short and stout and always less then 57% BDL. The second dorsal fins in H. alphus and H. macrophthalmus have anterior and posterior regions that are lobed and significantly taller than the middle region. However, the anterior region in H. alphus is 7.2-9.0% BDL as compared to 3.8-5.6% BDL in H. macrophthalmus, and posterior regions are taller in H. alphus, 4.4-5.7% BDL versus 2.2-3.8% BDL in H. macrophthalmus. The eyes are larger in H. alphus (greater then 40% HDL) than in H. macrophthalmus (less then 39.5% HDL). The snout of H. macrophthalmus is clearly more pointed at the tip, whereas in H. alphus it is blunt. Lateral line canals in the head, particularly IOA, OTM, and OCL of H. alphus are longer than in H. macrophthalmus (table 2). Lastly, secondary sexual characteristics differ between species in that the length of the frontal tenaculum is longer in H. alphus (32.5% HDL) than in H. macrophthalmus (16.5-20.3% HDL). The pre-pelvic tenacula in H. alphus contains four hooks on the outer margin whereas in H. macrophthalmus it contains three hooks. However, it is important to note that number of hooks on the pre-pelvic tenacula varies intraspecifically, so this feature alone is not sufficient to distinguish the two species. Discussion The new species Hydrolagus alphus sp. nov. may be restricted to the Galapagos as this is the only locality in which it is found. Endemism of fishes in the Galapagos Islands with low dispersal capabilities has been shown to be high (Grove and Lavenberg, 1997), and preliminary data from deepwater fishes (McCosker et al., 1997) also indicates a high degree of endemism. This suggests that Hydrolagus alphus sp. nov. may likely be endemic to the Galapagos Archipelago as well, but only thorough deepwater surveys of the Pacific coasts of Central and South America will bear this out. Chimaeroids have features consistent with species that tend to be more geographically restricted. They are oviparous, depositing large egg cases in mud or attached to stones on the sea floor (Bigelow and Schroeder, 1953). This mode of reproduction in chimaeras is not affected by ocean currents which normally facilitate dispersal of eggs and larval fishes in the open ocean. In addition, chimaeroids have a morphology consistent with slow swimming. Their large wing-like pectoral fins and flapping motion do not promote speed or the ability to swim long distances, thus their potential for long-distance dispersal is limited.Published as part of Kimberly L. Quaranta, Dominique A. Didier, Douglas J. Long & David A. Ebert, 2006, A new species of chimaeroid, Hydrolagus alphus sp. nov. (Chimaeriformes: Chimaeridae) from the Galapagos Islands., pp. 33-45 in Zootaxa 1377 on pages 36-4
Hydrolagus macrophthalmus
No full textHydrolagus macrophthalmus - 4 specimens (Chile). MNHNC P. 7282 (E.B.M.Ch.10.192), holotype, adult male, at time of description 625 mm TL, currently 385 mm TL (due to damage of specimen), 360 mm PCL, 296 BDL, preabyssmal zone off Valpraiso, January, 1959; MNHNC P. 5724, adult male, about 445 mm TL, 365 mm PCL, 296 BDL, off Valpariso (33°02, 71°39’W), determined by Ismael Kong U., 15 Sept 1974; MNHNC P. 6421 (A), adult female, 627 mm TL, 425 mm PCL, 355 mm BDL, vessel R/V Academic Knipovich, (41°04’5” S, 74°16’1” W), determined by Augusto Cornejo C., 300 m, 02 Mar 1973; MNHNC P. 6421 (B), adult female, 572 mm TL (tail broken), 493 mm PCL, 424 mm BDL, same information as (A). Hydrolagus macrophthalmus - 7 specimens (Peru). HUMZ 185708, adult female, 560 mm TL, 415 mm PCL, 342 mm BDL, Eastern Pacific, Peru (9-42.5'S - 9-43'S, 79-35.5'W - 79-43.5'W), 785 m; HUMZ 185709, adult male, 527 mm TL, 355 mm PCL, 358 BDL, Eastern Pacific, Peru, (9-42.5'S - 9-43'S, 79-35.5'W - 79-43.5'W), 787 m; HUMZ 167821, adult female, 515 mm TL, 420 mm PCL, 346 mm BDL, Eastern Pacific, Peru (10-12.2'S - 10-10.8'S, 79-06.3'W - 79-06.7'W), 1056 m; HUMZ 167443, adult Female, 636 mm TL, 424 mm PCL, 357 mm BDL, Eastern Pacific, Peru (9-20.5'S - 9-19.5'S, 79-47.7'W - 79- 48.4'W), 1160 m; HUMZ 167820, adult female, 594 mm TL, 425 mm PCL, 353 mm BDL, Eastern Pacific, Peru (10-12.2'S - 10-10.8'S, 79-06.3'W - 79-06.7'W), 1056 m; HUMZ 167128, adult male, 612 mm TL, 391 mm PCL, 320 mm BDL, Eastern Pacific, Peru (9-03.7'S - 9-06.5'S, 80-00.7'W - 80-00.6'W), 872 m; HUMZ 173320, adult female, 540 mm TL, 420 mm PCL, 346 mm BDL, Eastern Pacific, Peru (3-56.2'S - 4-03.4'S, 81- 16.8'W - 81-11.8'W), 590 m.Published as part of Kimberly L. Quaranta, Dominique A. Didier, Douglas J. Long & David A. Ebert, 2006, A new species of chimaeroid, Hydrolagus alphus sp. nov. (Chimaeriformes: Chimaeridae) from the Galapagos Islands., pp. 33-45 in Zootaxa 1377 on page 4
PESI - a taxonomic backbone for Europe
No full textThis is an open access article distributed under the terms of the Creative Commons Attribution License (CC BY 4.0), which permits unrestricted use, distribution, and reproduction in any medium, provided the original author and source are credited.
The attached file is the published version of the article.NHM Repositor
The international competitiveness of cava: success of a particular firm or the district ?
No full textFirst of all, the author wonders about the degree of success of the Catalan sparkling wine industry in the recent past. The comparison with the Italian sparkling spumante and also with the case of the most celebrated sparkling wine in the world, champagne, shows a very positive trend of the cava production and exports in the last three decades of the XXth century. Secondly, this paper focuses on the agent or cause responsible of this success. Is it due to a particular firm or should it be attributed to the whole industrial cava cluster around the area of Sant Sadurni dAnoia? More than two thirds of the exports correspond to a particular firm. In this sense, we should attribute the success to it. However, the historical explanation of the development of the industrial cava cluster in the main and well-kwown viticultural Catalan area of Penedes, shows that all producers have benefit from the Marshalian external economies due to this concentration. And the paper shows that the leading export firm would never have succeeded in the international market without the existence of this kind of invisible advantages.skilled labor, wine industry, wine trade, spumante, cava, cluster, champagne, sparkling wine, protectionism
Alla ricerca di un’archeologia perduta. Spunti e riflessioni su uno scavo di quaranta anni fa: Umberto Scerrato e il suo Sistan (In Search for a Lost Archaeology. Ideas and Thoughts on a forty years ago excavation: Umberto Scerrato and his Sistan
No full textThe author very shortly deals with the main scientific results of the Italian Excavations in Sistan on the site of Dahan-i e Ghulaman (Sistan). He focuses on the particular urban character of the site, which represent a unique example in the archaeological history of the Achaemenid time in the plateau
Author Correction: Visual field loss and vision-related quality of life in the Italian Primary Open Angle Glaucoma Study
No full textAn amendment to this paper has been published and can be accessed via a link at the top of the paper
Flight Simulator Transfer of Training Effectiveness in Helicopter Maneuvering Flight
No full textThis research aims to advance the state-of-the-art requirements for helicopter pilot training in flight simulators contributing to the rotorcraft safety enhancement framework. It has been conducted as part of the Marie Sk\l odowska-Curie European Joint Doctorate NITROS (Network for Innovative Training on Rotorcraft Safety).Training has always been the traditional answer to help pilots deal with flying vehicles and scenarios that, without adequate preparation, would otherwise be unforgiving. Due to the risks and costs involved in training for such critical circumstances, the exclusive use of in-flight training is untenable, especially for helicopters. A combination of simulator and in-flight training is the solution adopted to reduce accident rates and human fatalities in a safe and efficient manner and to fulfill the ever-harsher mandate for flawless performance required by the military domain. Inevitably, the use of simulation to support pilot training brings forward the issue of skills and performance transfer from the simulator to the actual aircraft, which is addressed in this thesis in relation to helicopters.The primary focus of flight simulation transfer-of-training research is to assess how learning a task in a flight simulator affects the trainee's performance capabilities in the same task in the actual aircraft. To explicitly measure the transfer of behavior learned in a certain setting (e.g., a simulator) to the evaluation setting of interest (e.g., a real aircraft), transfer-of-training experiments are one of the few available methods for direct evaluation of the training effectiveness. To measure pilot transfer of skills at least two groups of participants are required. The speed of learning in the actual aircraft by one (or more) "experimental" group(s), previously trained in the simulator, need to be compared with the learning performance of a "control" group having received no special previous training. While this design enables to directly assess the effectiveness of a simulator, it requires strictly balanced groups according to participants' relevant prior training and experience to deliver meaningful results.Several variations of this basic transfer model, named a true-transfer design, have also been proposed. The most popular is the simulator-to-simulator transfer model, also known as quasi-transfer design. In quasi-transfer experiments, participants are not transferred to the real-world setting, but to a different, often more realistic or enhanced, simulation environment. The quasi-transfer paradigm relies on the assumption that the more realistic simulator acts as a valid replacement for the actual aircraft. Although this is a strong assumption, its effectiveness for evaluating skill transfer is corroborated by experimental evidence. Furthermore, a quasi-transfer design avoids the costs, hazards, and scheduling hindrances (e.g., interruptions due to bad weather) of a true-transfer experiment and offers the possibility of safely investigating dangerous situations such as engine failures. Another issue arising from true-transfer studies (and from flight tests in general) is the reliability of the performance measurements in the real-world setting. Moreover, there are inevitable psychological differences in a pilot's mindset between training in a simulator or in the actual aircraft. This is not necessarily a disadvantage from a training perspective, because relieving the trainee of the stress and the workload deriving from auxiliary duties (e.g., safety and flight regulation aspects, communication, periodic systems monitoring, etc.) enables devoting more mental resources to learning.For this thesis, three quasi-transfer-of-training experiments were conducted to test the effectiveness of flight simulator training for two different helicopter tasks: hover and autorotation. The ability to hover, i.e., to remain in a nearly stationary flight condition, is the main capability that differentiates helicopters from fixed-wing aircraft. The ability to autorotate, i.e., to keep the rotor spinning by means of the airflow passing through it, is an essential emergency maneuver that enables helicopter pilots to often safely reach the closest suitable landing site in the event of an engine failure. These two maneuvers were not randomly chosen. The choice was based on the fact that hover and autorotation pertain to different phases of the helicopter pilot training syllabus. While both maneuvers need to be mastered by helicopter pilots, hover is generally the very first maneuver that student pilots learn to perform, whereas autorotation is practiced only when the trainee demonstrates a sufficient level of proficiency in maintaining/controlling the airspeed and the rotorspeed. Therefore, hover and autorotation can be characterized as a "basic" and an "advanced" maneuver, respectively. Furthermore, hover is performed in normal operating conditions, whereas an autorotation represents an abnormal mode of operation for helicopters and is thus performed only in emergency circumstances. On the other hand, hover is performed by helicopter pilots on a daily basis (or at least every time they fly). Fortunately, nowadays engine reliability is high and they seldomly fail, meaning that real power-out autorotations are not performed often. However, to be prepared for a potential occurrence, simulated engine-failures (generally with a power-recovery, i.e., terminating in a hover) are practiced during recurrent training and proficiency checks. It is therefore evident that issues in simulator training of the hover maneuver need to be assessed especially in relation to novices (ab-initio training), while those in simulator training of the autorotation maneuver require a focus on experienced pilots (recurrent training).The type of maneuver (e.g., basic or advanced), the operating condition (e.g., normal or abnormal mode of operation), and the trainees' characteristics (e.g., novice or experienced pilots) are all factors that play a role in the level of simulator fidelity needed for effective training. In contrast to the unquestioning and unceasing pursuit of high fidelity, which is typical of the simulation industry and is also supported by current regulations for flight simulator training devices, there is increasing evidence that adding more fidelity beyond a certain point results in a diminished degree of transfer of skills, especially for nonexpert pilots. Indeed, high fidelity also means high complexity, which generally requires more cognitive effort, thus increasing the trainee’s workload, which may, in turn, impede simulator learning. With the goal to seek more clarity with respect to the relation between fidelity and training effectiveness, a first quasi-transfer-of-training experiment was conducted, in which the simulator's objective fidelity (i.e., the quality of the cueing systems) was the independent variable. Two groups of task-na\"ive learners (a total of twenty-four participants) underwent a hover part-task training program, formulated according to Cognitive Load Theory, an instructional design theory that reflects the way humans process information. The experimental group first trained in a low-fidelity simulator (a Computer Based Trainer at the Max Planck Institute for Byological Cybernetics) and then transferred to a high-fidelity setting (the CyberMotion Simulator at the Max Planck Institute for Byological Cybernetics), while the control group received all its training in the high-fidelity simulator. The two groups were balanced according to participants' manual control skills, which were evaluated through a pre-experimental aptitude test (a two-axes compensatory tracking task). During the evaluation phase, which both groups performed in the high-fidelity simulator, no statistically significant differences were found between the two groups in all the dependent measures. Of course, this does not directly imply that the two simulators are equally effective, as the hover part-task training program likely had a mitigating effect, supporting the idea that the lack of simulator objective fidelity can be compensated by the use of instructional design (i.e., a proper training program tailored to the trainees' needs). This can be verified in future experiments using a third group of task-na\"ive learners, trained with a different hover training program in the low-fidelity simulator who are then transferred to the high-fidelity setting to prove this hypothesis.This thesis also describes two quasi-transfer-of-training experiments that focused on autorotation and had the same setup (the SIMONA Research Simulator at Delft University of Technology), but used two different helicopter flight mechanics models, characterized by a different level of fidelity. The lower-fidelity model was chosen to gain a simple understanding of the flight dynamics in autorotation, that could then be more easily extended to a higher-fidelity model. These experiments, in which the helicopter dynamics were chosen as the independent variable, were motivated by an example of in-flight-to-in-flight negative transfer of training reported in several helicopter accidents. Indeed, many engine failure accidents result from an apparent loss in rotor performance (different helicopter dynamics), which is unexpected for pilots who only practiced autorotations with a power recovery (i.e., terminating in a hover). For helicopters with free-turbine engines, even in a ground-idle setting, the engine still transmits some power to the rotor. This is a clear example of in-flight-to-in-flight negative transfer of training: practicing power-recovery autorotations (task A) interferes with learning or performing real power-out autorotations (task B) for helicopters with free-turbine engines, due to the fact that there is a crucial mismatch between the helicopter dynamics characteristics in the two task situations. Here, a pilot's mental model of the helicopter is not representative of the actual helicopter, which requires a different control strategy than learned during training.Experienced helicopter pilots participated in the two quasi-transfer-of-training experiments on autorotation. They were divided in two groups, which were balanced according to participants' background (license type) and experience (flight hours), and performed a straight-in autorotation maneuver with two different helicopter dynamics presented in a different sequence. The two dynamics used in the experiments were selected to require a different level of pilot control compensation. To this end, a sensitivity analysis on the helicopter eigenmodes was performed to understand which design parameters control the autorotative flare index, a metric to evaluate autorotative performance in terms of available energy over required energy and thus influence helicopter dynamics in autorotation. This was achieved through the structural evaluation and comparison of the helicopter natural modes of motion in steady-descent autorotation. Thirty-two configurations were compared by individually varying the main rotor blade chord, the main rotor radius, the main rotorspeed and the helicopter weight from the baseline value (Bo-105 helicopter) to get eight different values of the autorotation index, spanning from 5 to 40 ft3/lb. This range was chosen after comparing the autorotative flare indices for various existing helicopters. Among these configurations, the two requiring the most and the least pilot control compensation were selected.In the first experiment on autorotation, fourteen pilots performed the straight-in autorotation maneuver controlling a 3-degrees-of-freedom (DOF) longitudinal dynamics + rotor speed DOF model. Ten pilots performed the same task with a 6-DOF rigid-body dynamics + rotor speed DOF model in the second experiment. In both experiments clear positive transfer was found from the most to the least demanding helicopter dynamics, but not the opposite. This is observed especially for the rate of descent at touch-down, which is considered the key indicator of a smooth landing. The outcome of these two experiments suggests the need to update the current simulator training syllabus for autorotation to include a wide range of helicopter configurations with different handling characteristics. Such configurations can be obtained for example considering different models of the same helicopter family, to give to the trainee the opportunity to familiarize with helicopters with different sizes, dynamics and "feel". This can help inexperienced pilots to better understand that an autorotation is not a "by-the-numbers" procedure and that adaptability and judgement of the pilot should always cover a prominent role in the accomplishment of the task.To strenghten the experiments on autorotation, a thourough analysis was conducted to investigate the effects of the rotorspeed degree-of-freedom in autorotation on the classical rigid-body modes. Although the developed 3-DOF and 6-DOF models are characterized by a different level of fidelity, good agreement in terms of stability characteristics of the longitudinal modes of motion was found between the two models. Especially the phugoid and the heave-subsidence modes are strongly affected by the additional rotorspeed degree of freedom, meaning that autorotation requires a different stabilization strategy by the pilot with respect to straight level flight. On the contrary, the pitch subsidence in both models and the lateral-directional modes in the 6-DOF rigid-body helicopter model do not change significantly in steady-descent in autorotation with respect to straight level flight.In conclusion, this thesis provides enhanced insight into helicopter pilot training in flight simulators by addressing two critical training tasks, hover (Part I of this thesis) and autorotation (Part II of this thesis), that represent two of a helicopter's most unique capabilities. With these new insights, this thesis lays the foundations for an enhanced understanding of the future requirements for helicopter pilots training in flight simulators, which will become even more important considering the current trends towards Urban Air Mobility. Indeed, the transition from helicopters as a niche sector in the aerospace industry to the widespread future use of personal aerial vehicles (PAVs) based on rotorcraft concepts needs to be accompanied by a disruptive change in aviation regulations, encompassing every aspect of safety, including training. Even though these future PAVs will be characterized by a high level of automation, the human operators will keep playing an important role in the safe operation of the flight, hence raising the need to develop training requirements for PAV pilots.Control & Simulatio
Cells assemble invadopodia-like structures and invade into matrigel in a matrix metalloprotease dependent manner in the circular invasion assay
No full textThe ability of tumor cells to invade is one of the hallmarks of the metastatic phenotype. To elucidate the mechanisms by which tumor cells acquire an invasive phenotype, in vitro assays have been developed that mimic the process of cancer cell invasion through basement membrane or in the stroma. We have extended the characterization of the circular invasion assay and found that it provides a simple and amenable system to study cell invasion in matrix in an environment that closely mimics 3D invasion. Furthermore, it allows detailed microscopic analysis of both live and fixed cells during the invasion process. We find that cells invade in a protease dependent manner in this assay and that they assemble focal adhesions and invadopodia that resemble structures visualized in 3D embedded cells. We propose that this is a useful assay for routine and medium throughput analysis of invasion of cancer cells in vitro and the study of cells migrating in a 3D environment
