Conspicuous Landmarks Research Articles

Spatial Learning by Using Non-Visual Geometry and a Visual 3D Landmark in Zebrafish (Danio rerio).

Fish conjoin environmental geometry with conspicuous landmarks to reorient towards foraging sites and social stimuli. Zebrafish (Danio rerio) can merge a rectangular opaque arena with a 2D landmark (a blue-colored wall) but cannot merge a rectangular transparent arena with a 3D landmark (a blue cylinder) without training to "feel" the environment thanks to other-than-sight pathways. Thus, their success is linked to tasks differences (spontaneous vs. rewarded). This study explored the reorientation behavior of zebrafish within a rectangular transparent arena, with a blue cylinder outside, proximal to/distal from a target corner position, on the short/long side of the arena. Adult males were extensively trained to distinguish the correct corner from the rotational one, sharing an equivalent metric-sense relationship (short surface left, long surface right), to access food and companions. Results showed that zebrafish's reorientation behavior was driven by both the non-visual geometry and the visual landmark, partially depending on the landmark's proximity and surface length. Better accuracy was attained when the landmark was proximal to the target corner. When long-term experience was allowed, zebrafish handled non-visual and visual sensory stimulations over time for reorienting. We advance the possibility that multisensory processes affect fish's reorientation behavior and spatial learning, providing a link through which to investigate animals' exploratory strategies to face situations of visual deprivation or impairments.

Real-time virtual sonography-assisted radiofrequency ablation in liver tumors with conspicuous or inconspicuous images or peritumoral landmarks under ultrasonography

ObjectivesThe objectives of this study were to determine the primary technique effectiveness (PTE), to compare the complete response and local recurrence rates between conspicuous and inconspicuous tumors using single and switching electrodes of real-time virtual sonography (RVS)-assisted radiofrequency ablation (RFA) in conspicuous and inconspicuous hepatic tumors under conventional ultrasonography (US).Subjects and methodWe compared the complete ablation of inconspicuous tumors with and without anatomical landmark (N = 54) with conspicuous liver tumors (N = 272). Conventional US imaging was done initially, and then these images were fused with CT or MRI arterial-venous-wash-out cross-sectional studies and synchronized with real-time US images.ResultsRVS-assisted RFA was technically feasible in all patients. The PTE rate after the first ablation was 94% (245/261) for conspicuous tumors, 88% (7/8) in inconspicuous tumors with landmark, and 78% (36/46) in inconspicuous tumors without landmark. The complete response (p = 0.1912 vs. p = 0.4776) and local recurrence rate (p = 0.1557 vs. p = 0.7982) were comparable in conspicuous tumors of both HCC and liver metastasis group when single or multiple switching was used. The cumulative local recurrence in the conspicuous and inconspicuous tumors of the HCC group (p = 0.9999) was almost parallel after 12 (10% vs. 4%) and 24 (13% vs. 4%) months of follow-up. In the liver metastasis group, the cumulative local recurrence for conspicuous tumors (p = 0.9564) was nearly equal after 12 and 24 months of monitoring (24% vs. 27%) while no recurrence was incurred for the inconspicuous tumors.ConclusionRVS-assisted RFA is an effective tool for the treatment of conspicuous and inconspicuous HCC and hepatic metastasis.

The role of landmarks in territory maintenance by the black saddlebags dragonfly, Tramea lacerata

Territoriality can reduce competition for resources, but territorial defense can be costly; therefore, any behavior that reduces territorial costs may increase the net benefit of territoriality. Some species will align their territory boundaries with conspicuous landmarks that may serve to reduce defense costs. Dragonflies, including black saddlebags (Tramea lacerata), defend territories at breeding sites, keeping rival males away to allow themselves access to females. We used three treatments to investigate whether T. lacerata used landmarks: constraining landmarks (an object that provided a physical barrier to flight), non-constraining landmarks (an object of the same dimensions and construction that did not impede flight), and a control without landmarks. We observed patrolling male black saddlebags and recorded the locations of turns at their territory boundary and interactions with other dragonflies. When either type of landmark was present, individuals placed their boundary at the landmark far more often than any other location. In addition, individuals that used landmarks had a significantly narrower range of turn locations than those that did not. Unlike other studies, the use of a landmark did not seem to reduce defense costs, and interestingly not all individuals used landmarks when they were provided. We hypothesize that in this species, landmarks may only reduce costs during territory establishment, rather than during territory maintenance. Alternatively, landmarks may serve as part of a spatial reference system that aids male dragonflies in efficiently searching for females, and thus may be more important in increasing benefits rather than decreasing the costs of territoriality.

Spatial Orientation in Japanese Quails (Coturnix coturnix japonica)

Finding a given location can be based on a variety of strategies, for example on the estimation of spatial relations between landmarks, called spatial orientation. In galliform birds, spatial orientation has been demonstrated convincingly in very young domestic chicks. We wanted to know whether adult Japanese quails (Coturnix coturnix japonica) without food deprivation are also able to use spatial orientation. The quails had to learn the relation of a food location with four conspicuous landmarks which were placed in the corners of a square shaped arena. They were trained to find mealworms in three adjacent food cups in a circle of 20 such cups. The rewarded feeders were located during training between the same two landmarks each of which showed a distinct pattern. When the birds had learned the task, all landmarks were displaced clockwise by 90 degrees. When tested in the new situation, all birds redirected their choices with respect to the landmark shift. In subsequent tests, however, the previously correct position was also chosen. According to our results, quails are using conspicuous landmarks as a first choice for orientation. The orientation towards the previously rewarded location, however, indicates that the neuronal representation of space which is used by the birds also includes more fine grain, less conspicuous cues, which are probably also taken into account in uncertain situations. We also presume that the rare orientation towards never rewarded feeders may be due to a foraging strategy instead of being mistakes.

Active concomitant counterclockwise rotation and northwards translation of Africa during the Albian–Campanian time: A paleomagnetic study on the Wadi Natash alkaline volcanic province (104–78 Ma), South Eastern Desert, Egypt

Africa was a key tectonic unit in the geologic evolution of the Tethyan realm in the Middle–Late Cretaceous during the rifting of the South-Equatorial Atlantic Ocean. This research sheds light on the tectonic evolution of Africa during the Albian–Campanian time. The two end members of the Wadi Natash alkaline volcanic province [WNAVP] (104–78 Ma) in the South Eastern Desert of Egypt were studied paleomagnetically. The WNAVP (24.5° N–34.25° E) is made up of a thick succession of differentiated lava flows grading from alkali olivine basalt [AOB] followed by hawaiite–mugearite and benmoreite flows with abundant sandstone interbeds, all intruded by a large number of trachyte/phonolite [Tr/Ph] circular lava domes and ring dykes forming conspicuous landmarks in the province. The oldest flows of the AOB (104 ± 7 Ma) and the youngest Tr/Ph plugs and ring dykes (86–78 Ma) as well as the interbedded Turonian “Taref” sandstone formation [previously known as “Nubian” sandstone] were sampled all over the province which covers more than 500 km 2. The isothermal remanent magnetization [IRM] study pointed to magnetite family as the major remanence in Wadi Natash volcanics, with little contribution from goethite/hematite minerals. On the other hand, goethite and/or hematite are the dominant remanence carriers in the interbedded “Taref” sandstone. After the progressive stepwise thermal demagnetization of all samples, the characteristic remanence [ChRM] direction for each rock type was visually isolated and its best-fit line was calculated, followed by the site-means, rock-unit means and the paleomagnetic poles. This paleomagnetic study revealed that: 1- In the tilt-corrected coordinates, the mean ChRM of the oldest AOB flows [N = 12 sites] was Dec./Inc. = 340°/−10° [K = 54, α95 = 6º] yielding a north pole at 55° N/250° E. The ChRM of the youngest Tr/Ph ring dykes and plugs [N = 10 sites] was Dec./Inc. = 354°/3.5° [K = 60, α95 = 6.3º] yielding a north pole at 66.5° N/229° E. 2- On the other hand, the site-mean ChRMs of the “Taref” sandstone interbeds [N = 8 sites], in the present-day in-situ coordinates, are clustered around the present-day geomagnetic field with a mean Dec./Inc. = 3°/33° [K = 37, α95 = 9.3°] yielding a north pole at 83° N/191° E. The two paleomagnetic poles of the AOB and the Tr/Ph are in accordance with Albian–Campanian poles from Africa [including Madagascar] and those rotated from the main Cratons such as the North American Craton, Europe [including Greenland and Iberia], South America and India using the published Plate Kinematics and Paleomagnetic Euler Pole [PEP] rotation parameters. Paleogeographically, the two obtained poles of Wadi Natash volcanics place the African Plate at two different azimuths and paleolatitudes during Albian–Cenomaniam and Santonian– Middle Campanian. Tectonically, these two paleomagnetic poles point to an active synchronous northwards translation associated with a counterclockwise rotational convergence of Africa towards Eurasia during the Albian–Campanian time. Between the time of the AOB eruption [104 ± 7 Ma] and the intrusion of the TR/Ph [86–78 Ma] Africa concomitantly rotated counterclockwise about 14° and translated northwards towards Eurasia about 6° of latitude.

Introduction to the Maastricht workshop: lessons from the past and new directions in galactosemia

Hereditary galactosemia is an autosomal recessive genetic disorder of carbohydrate metabolism (OMIM 230400; Fridovich-Keil andWalter 2008; Elsas 2010; Berry and Walter 2011). The mutated gene encodes a protein, galactose1-phosphate uridyltransferase (GALT, EC 2.7.7.12), that catalyzes the conversion of galactose-1-phosphate and UDPglucose to UDP-galactose and glucose-1-phosphate (Fig. 1). In the newborn period, a life-threatening disease with multiorgan involvement emerges, particularly in those infants ingesting lactose in breast milk and proprietary baby formulas containing the ingredients of cow’s milk (Berry and Walter 2011). The first observation of this nutritional toxicity state involving the neonate and breast milk was by von Reuss in 1908 (von Reuss 1908). In the next decade, Goppert documented the presence of excess galactose in the urine of a similarly affected infant (Goppert 1917). The first well characterized infant with hypergalactosemia and galactosuria who responded to a lactose-restricted diet was described by Mason and Turner in 1935 (Mason and Turner 1935). This paper, describing an African-American infant with a variant form of galactosemia, served to reveal marked hypergalactosemia as an integral component of GALT deficiency. However, establishment of the abnormal biochemistry awaited the discovery of Schwarz in 1956 (Schwarz et al. 1956) that the substrate, galactose-1-phosphate, was elevated in erythrocytes from galactosemic patients exposed to galactose, and the demonstration later that year in the Kalkar laboratory that GALTenzyme activity was absent (Isselbacher et al. 1956). This rare Mendelian disorder with a world-wide frequency of 1/40,000 to 1/60,000 newborn infants entered the modern era of molecular biology when Reichardt and Berg cloned a GALT cDNA from a human liver library (Reichardt and Berg 1988), and its correct cDNA sequence enabled cloning and delineation of the structure of the GALT gene (Flach et al. 1990; Leslie et al. 1992). Soon thereafter, many causative gene mutations were identified producing a heterogeneous array of impaired pGALT function (Elsas and Lai 1998; Tyfield 2000; Calderon et al. 2007). It was clear in the decades following the landmark Mason and Turner paper that restriction of galactose intake in the affected newborn infant would usually permit survival and allow the following early infantile complications to remit, resolve or disappear: poor growth, poor feeding, emesis, jaundice, liver enlargement and dysfunction that includes hyperbilirubinemia, transaminasemia, hypofibrinoginemia with bleeding diathesis, cataracts, encephalopathy, including lethargy, irritability and hypotonia, hyperchloremic metabolic acidosis, albuminuria, generalized aminoaciduria and anemia. Yet, between 1970 and 1990, there was a growing awareness that there were “clouds over galactosemia” (Anonymous 1982; Holton and Leonard 1994), that patients were not faring as well as physicians had expected (Komrower and Lee 1970; Lee 1972; Fishler et al. 1972, 1980; Komrower 1982; Waisbren et al. 1983; Gitzelmann and Steinmann 1984), especially given the fact that lactose restriction largely eliminates death from E. coli sepsis (Levy et al. 1977). And, this was all the more poignant, as infants Communicated by: Estela Rubio

Suburban Diversity and Economic Inequality: Can the Democrats Meet the Challenge?

Since 2004, the sixty-two-foot statue of Jesus erected by the Solid Rock Church has stood as one of the most conspicuous landmarks in southern Ohio, located at the midpoint of the fifty-mile corridor of suburban sprawl along I75 between Cincinnati and Dayton. The evangelical megachurch built the "King of Kings" statue, featuring a fiberglass and styrofoam Messiah rising with uplifted arms from a large reflecting pool, to proclaim the gospel to the surrounding community and especially to motorists passing by on the highway. This year, the icon, tagged with such nicknames as "Touchdown Jesus" and "Drowning Jesus," provided an even greater spectacle when a lightning strike burned it down late in the evening of June 14. The complex's large neon billboard, which flashes messages such as "No God, No Peace," emerged unscathed. Solid Rock Church immediately promised to rebuild what it had claimed as the largest sculpture of Jesus Christ in the United States, while secular critics across America had a field day mocking the tacky tastes and in-your-face religious values of this Middle American exurb. A columnist for the San Francisco Chronicle sarcastically wondered if gay rights activists had torched the giant Jesus as payback for heartland homophobia and imagined "fundamentalists scurry[ing] about in a baffled frenzy, unsure what it all might mean." Others observed that God had spared the thriving Hustler Hollywood megastore, located at the same interstate exit, which Larry Flynt opened in his home state over the resistance of public officials and a religious right group called Citizens for Community Values.

How ants find each other; temporal and spatial patterns in nuptial flights

Reproduction is a key factor in understanding population ecology and therefore species occurrence. However, patterns in reproductive behaviour for distinct ant species remain insufficiently known. In this paper strategies in mate finding are studied for six ant species (Lasius niger, Lasius umbratus, Temnothorax nylanderi, Myrmica rubra, Myrmica ruginodis, Stenamma debile) in a forest – forest edge – agricultural field gradient. Using window traps, we studied whether these species had a restricted nuptial flight season, displayed swarming behaviour, and whether the alates aggregated at the forest edge. The flight season was limited to one month or less for L. niger, T. nylanderi, M. rubra, M. ruginodis and S. debile. Swarming behaviour occurred in all but one (L. umbratus) species. Although none of the six species seemed to have highest nest density at the forest edge, three of them, M. rubra, M. ruginodis and S. debile, showed male aggregations there, indicating this to be the main reproduction site. This last finding could be due to a more suitable micro-climate, but most likely, edges are conspicuous land marks which are used by ants to meet mates. The behavioural patterns of ant sexuals at the forest edge can influence dispersal possibilities in fragmented landscapes, reproductive success and nest densities.

Homing flights of pigeons over familiar terrain

The routes of nine adult pigeons repeatedly released from a familiar site 9.1 km west of their Frankfurt home loft were recorded with the help of GPS-based flight recorders. Analysis of the tracks shows considerable variability not only between individual birds, but also between the tracks of each individual concerning duration of flight, flying speed and the routes chosen. The efficiencies (direct route divided by length of the route taken) are fairly high, ranging from 0.77 to 0.91. They did not increase significantly, nor did the tracks become more similar, as the pigeons became more familiar with the area between the release site and the loft. Homing flights begin with a starting phase of lower efficiency. Five hundred metres from the release point, all birds were significantly oriented; at 2500 m, they showed a small southerly deviation from the home direction. The overland flights were mostly very straight, with efficiencies above 0.9, and so was the approach to the loft. The flying corridor crossed the western suburbs of metropolitan Frankfurt, rich with conspicuous landmarks and highways, but an obvious influence of these features was not observed. In contrast to what was reported from other areas, our pigeons did not show a pronounced tendency to follow highways. Loops and detours in the course of the return flights are in part attributed to social interactions with other pigeons.

Mental maps in chacma baboons (Papio ursinus): using inter-group encounters as a natural experiment

Encounters between groups of wild chacma baboons (Papio ursinus) can be viewed as a natural experiment to investigate the nature of these primates' mental representations of large-scale space. During a 16-month field study in a high population density habitat we recorded the foraging routes and the most important resources of a group of 25 individuals. Also, we estimated the locations of additional baboon groups relative to the study group. Routes were less linear, travel speed was higher, and inter-resource distances were larger when other groups were present within 500 m of the focal group; thus, the study group avoided others by taking detours. We predicted that evasive manoeuvres would be characteristic of different possible orientation mechanisms, and compared them with our observations. We analysed 34 evasive manoeuvres in detail. In an area that lacked prominent landmarks, detours were small; larger detours occurred when resources were directly visible, or in the vicinity of a hill offering conspicuous landmarks. In areas without prominent landmarks, detours were along familiar routes and waiting bouts of up to 60 min occurred; on one occasion the study group aborted their entire day's journey. We discuss these findings in the light of time and energy costs and suggest that the baboons lack the ability to compute Euclidean relations among locations, but use network maps to find their way to out-of-sight locations.

Learning to select distinctive landmarks for mobile robot navigation

In landmark-based navigation systems for mobile robots, sensory perceptions (e.g., laser or sonar scans) are used to identify the robot’s current location or to construct internal representations, maps, of the robot’s environment. Being based on an external frame of reference (which is not subject to incorrigible drift errors such as those occurring in odometry-based systems), landmark-based robot navigation systems are now widely used in mobile robot applications. The problem that has attracted most attention to date in landmark-based navigation research is the question of how to deal with perceptual aliasing, i.e., perceptual ambiguities. In contrast, what constitutes a good landmark, or how to select landmarks for mapping, is still an open research topic. The usual method of landmark selection is to map perceptions at regular intervals, which has the drawback of being inefficient and possibly missing ‘good’ landmarks that lie between sampling points. In this paper, we present an automatic landmark selection algorithm that allows a mobile robot to select conspicuous landmarks from a continuous stream of sensory perceptions, without any pre-installed knowledge or human intervention during the selection process. This algorithm can be used to make mapping mechanisms more efficient and reliable. Experimental results obtained with two different mobile robots in a range of environments are presented and analysed.

Geometric modules in animals' spatial representations: A test with chicks (Gallus gallus domesticus).

Recent work has shown that in place-finding tasks rats rely on the geometric relations between the goal object and the shape of the environment. We tested young chickens (Gallus gallus domesticus) on similar tasks in a reference memory paradigm to determine whether differences exist between species in the ability to use geometric and nongeometric spatial information. The main findings were that chicks: (a) encoded and used both geometric and nongeometric (featural) information; (b) did not use the overall spatial arrangement of the features; (c) relied primarily on nongeometric cues when faced with contradictory information. Two mechanisms are evident in chicks' spatial representations: a metric frame for encoding the spatial arrangement of surfaces as surfaces and a cue-guidance system for encoding conspicuous landmarks near the target. The possibility of hierarchical organization and species differences in these two mechanisms are discussed.

A neuroanatomical map of the suboesophageal and prothoracic ganglia of the honey bee ( Apis mellifera )

The basic organization of the prothoracic and suboesophageal ganglia of the honey bee is described from transverse, horizontal, and sagittal serial sections by using a variety of staining methods. Drawings of sections demonstrate neuropils, tracts, commissures, clusters of somata and other conspicuous landmarks. These provide the elements of a map of the ganglion in which specific neurons can be related to their structural context. The prothoracic ganglion contains nine longitudinal tracts in each hemiganglion. Six main dorsal and four ventral commissures link the two halves of the ganglion together. Other conspicuous structures are the ventral association centre and a T-tract: a ring tract is not strongly developed. The suboesophageal ganglion (SOG) is a fusion of the mandibular, maxillary, and labial neuromeres, the latter clearly showing the same basic organization as that found in the prothoracic ganglion. The more anterior mandibular and maxillary neuromeres successively decrease in volume compared with the posterior labial neuromere. Whereas the ventral parts of the neuromeres are demarcated from each other by prominent midline tracts, the dorsal part of each neuromere is confluent with the next. This may be, in part, due to the tilt of about 90° in the anterior-posterior axis (neuraxis) between the suboesophageal ganglion and the brain. Presumably, in morphogenesis this results in a compression of the dorsal parts of the suboesophageal ganglion. Eight longitudinal tracts run through each half of the ganglion. The number of main dorsal commissures declines from six in the labial to five in the maxillary and three in the mandibular neuromere. There are five ventral commissures in the maxillary, and four in both the mandibular and labial neuromeres. The organization of the suboesophageal and pro­thoracic ganglia in the honey bee is compared with those found in the cockroach, locust and cricket. The data support the hypothesis that insect ganglia have a common morphological building plan.

Observations of a Large Roost of Common Ravens

Observations of a Large Roost of Common Ravens

III. On some Special Indications of Volcanic Action in the Carboniferous Period at Burntisland, Firth of Forth

On the northern margin of the Firth of Forth, opposite Edinburgh, a line of steep craggy slope sweeps round from behind the village of Burntisland to the shore about half a mile eastward. The highest and most precipitous portion rises to a height of 631 feet; and the space between its base and the shore is so short that when seen from a short distance, the hill seems to shoot almost directly out of the sea. Hence these heights form conspicuous landmarks all over the Lothians. Their scarred fronts and verdurous slopes bear all the characteristic features of the minor hills in the lowlands of Scotland — a union of brown mouldering crag, often steep and bold, with soft green hollows, and with shelving sides that are either cumbered with ruins from the cliff overhead, or dotted with bushes of golden gorse. Such scenery is to a geological eye eminently ‘trappean;’ it at once suggests beds of greenstone, basalt, and ash, with the other concomitants of ancient volcanic eruptions. And truly amid all the rich development of volcanic phenomena in these Lowlands, the rocks of the Burntisland shore deserve to stand up as conspicuous landmarks. They have been laid bare by rains and frosts and the waves of the Firth along some miles of the coast-line, where they can be studied, bed after bed, in the minutest detail. I know of no such section in any other part of the kingdom.