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Spatial Organization (spatial + organization)
Selected AbstractsA CITY IN MOTION: TIME-SPACE ACTIVITY AND MOBILITY PATTERNS OF SUBURBAN INHABITANTS AND THE STRUCTURATION OF THE SPATIAL ORGANIZATION OF THE PRAGUE METROPOLITAN AREAGEOGRAFISKA ANNALER SERIES B: HUMAN GEOGRAPHY, Issue 2 2007Jakub Novák ABSTRACT. This contribution attempts to reveal the relations between new suburban areas and other parts of the Prague metropolitan area by investigating the time-space activity and mobility patterns of the inhabitants of newly built suburban districts. The focus on some aspects of the everyday life of people in new suburbs helps us to identify the impact of suburbanization on the changing geography of the metropolitan region and to better understand how the spatial organization of the Prague metropolitan area is produced, reproduced and transformed. We use several interrelated concepts, which serve the theoretical foundation of our work, namely time geography, structuration theory and the post-communist city. The empirical data utilized are primarily based on 262 diaries completed by eighty-eight individuals from thirty-eight households, accompanied by household questionnaires and interviews with the heads of households. The research confirmed the implicit, generally unspoken view that new suburbs in the Prague metropolitan region are heavily dependent on the core of the metropolitan area for the provision of jobs and services. However, newly built suburban shopping facilities to some extent disrupt this pattern, keeping some daily activities of inhabitants within the suburban zone. In addition to empirical observations, the key purpose of this contribution has been to discuss and apply time geography concepts and methods to the research of urban restructuring, and to understand the structuration of metropolitan spatial organization. [source] Spatial organization, group living and ecological correlates in low-density populations of Eurasian badgers, Meles melesJOURNAL OF ANIMAL ECOLOGY, Issue 3 2002Eloy Revilla Summary 1,Territoriality and group living are described in a low-density population of Eurasian badgers, Meles meles L., by studying the patterns of spatial grouping and territory marking, as well as the differences between individuals in some of their characteristics (body condition and dispersal) and in their space use (seasonally, periods of activity and interaction between pairs of individuals) under strong seasonal fluctuations in the availability of the key resource (young rabbits, Oryctolagus cuniculus L.). Finally, the role of the spatial distribution of the main prey (young rabbits) in the development of sociality was also studied in order to test some of the assumptions and predictions of the resource dispersion hypothesis (RDH). 2,Badgers were territorial, showing a flexible system of territory marking, which includes the marking of the most used areas (sett-latrines at the centres of activity) and additionally, at the smaller territories, a system of border-latrines in the areas of contact between territories. The maximum use of border-latrines was associated with the reproductive season, and that of sett-latrines with the season of food scarcity. 3,In the study area where badgers had rabbits as main prey, territories were occupied by small groups of animals, formed by one adult female who reproduced, one adult male who also showed signs of reproductive activity, the cubs of the year (if there was reproduction) and some animals born during previous years, which remained in their natal territory until their dispersal (normally during the mating season of their third or fourth year of life). This system was not strictly fixed as males, given the opportunity, expanded their territories to encompass additional females. Territories in another study site were occupied by one adult female (marked), plus the cubs of the year and another adult individual (unmarked). 4,In winter and spring dominant females and subordinates used only a small fraction of their territories, moved short distances, at a low speed and covering small areas per night. These seasons corresponded with the reproduction of rabbits (highest food availability). Dominant females were the only individuals using all the territory available in the summer (lowest food availability), when badgers had the worst body condition. Food availability increased again in autumn, as did body condition, while range sizes were again reduced. Dominant males used the same proportion of their territories over all seasons. However, in winter (reproductive season) they moved faster, over longer distances, and covered larger areas per period of activity. These results indicate that use of space by dominant males was affected by different factors from that of dominant females and subordinates. 5,RDH does not seem to explain group living in our populations because: (a) territoriality in each pair of primary animals was driven by different factors (trophic resources for females and females for males); (b) dominant males acted as expansionists; and (c) territory size was related to its richness and not to patch dispersion. 6,We propose an integrative hypothesis to explain not only group formation but also interpopulation variability in the social organization of badgers within ecological, demographic and behavioural constraints and in the light of current theory on delayed dispersal. [source] Spatial organization and isotubulin composition of microtubules in epidermal tendon cells of Artemia franciscanaJOURNAL OF MORPHOLOGY, Issue 2 2005Godelieve R.J. Criel Abstract Epidermally derived tendon cells attach the exoskeleton (cuticle) of the Branchiopod crustacean, Artemia franciscana, to underlying muscle in the hindgut, while the structurally similar transalar tendon (epithelial) cells, which also arise from the epidermis and are polarized, connect dorsal and ventral exopodite surfaces. To establish these latter attachments the transalar tendon cells interact with cuticles on opposite sides of the exopodite by way of their apical surfaces and with one another via basal regions, or the cuticle attachments may be mediated through linkages with phagocytic storage cells found in the hemolymph. In some cases, phyllopod tendon cells attach directly to muscle cells. Tendon cells in the hindgut of Artemia possess microtubule bundles, as do the transalar cells, and they extend from the basal myotendinal junction to the apical domain located near the cuticle. The bundled microtubules intermingle with thin filaments reminiscent of microfilaments, but intermediate filament-like structures are absent. Microtubule bundles converging at apical cell surfaces contact structures termed apical invaginations, composed of cytoplasmic membrane infoldings associated with electron-dense material. Intracuticular rods protrude from apical invaginations, either into the cuticle during intermolt or the molting fluid in premolt. Confocal microscopy of immunofluorescently stained samples revealed tyrosinated, detyrosinated, and acetylated tubulins, the first time posttranslationally modified isoforms of this protein have been demonstrated in crustacean tendon cells. Microfilaments, as shown by staining with phalloidin, coincided spatially with microtubule bundles. Artemia tendon cells clearly represent an interesting system for study of cytoskeleton organization within the context of cytoplasmic polarity and the results in this article indicate functional cooperation of microtubules and microfilaments. These cytoskeletal elements, either acting independently or in concert, may transmit tension from muscle to cuticle in the hindgut and resist compression when connecting exopodite cuticular surfaces. © 2004 Wiley-Liss, Inc. [source] On functional motor adaptations: from the quantification of motor strategies to the prevention of musculoskeletal disorders in the neck,shoulder regionACTA PHYSIOLOGICA, Issue 2010P. Madeleine Abstract Background:, Occupations characterized by a static low load and by repetitive actions show a high prevalence of work-related musculoskeletal disorders (WMSD) in the neck,shoulder region. Moreover, muscle fatigue and discomfort are reported to play a relevant initiating role in WMSD. Aims: To investigate relationships between altered sensory information, i.e. localized muscle fatigue, discomfort and pain and their associations to changes in motor control patterns. Materials & Methods:, In total 101 subjects participated. Questionnaires, subjective assessments of perceived exertion and pain intensity as well as surface electromyography (SEMG), mechanomyography (MMG), force and kinematics recordings were performed. Results:, Multi-channel SEMG and MMG revealed that the degree of heterogeneity of the trapezius muscle activation increased with fatigue. Further, the spatial organization of trapezius muscle activity changed in a dynamic manner during sustained contraction with acute experimental pain. A graduation of the motor changes in relation to the pain stage (acute, subchronic and chronic) and work experience were also found. The duration of the work task was shorter in presence of acute and chronic pain. Acute pain resulted in decreased activity of the painful muscle while in subchronic and chronic pain, a more static muscle activation was found. Posture and movement changed in the presence of neck,shoulder pain. Larger and smaller sizes of arm and trunk movement variability were respectively found in acute pain and subchronic/chronic pain. The size and structure of kinematics variability decreased also in the region of discomfort. Motor variability was higher in workers with high experience. Moreover, the pattern of activation of the upper trapezius muscle changed when receiving SEMG/MMG biofeedback during computer work. Discussion:, SEMG and MMG changes underlie functional mechanisms for the maintenance of force during fatiguing contraction and acute pain that may lead to the widespread pain seen in WMSD. A lack of harmonious muscle recruitment/derecruitment may play a role in pain transition. Motor behavior changed in shoulder pain conditions underlining that motor variability may play a role in the WMSD development as corroborated by the changes in kinematics variability seen with discomfort. This prognostic hypothesis was further, supported by the increased motor variability among workers with high experience. Conclusion:, Quantitative assessments of the functional motor adaptations can be a way to benchmark the pain status and help to indentify signs indicating WMSD development. Motor variability is an important characteristic in ergonomic situations. Future studies will investigate the potential benefit of inducing motor variability in occupational settings. [source] Microtubule-dependent organization of subcortical microfilaments in the early Drosophila embryoDEVELOPMENTAL DYNAMICS, Issue 3 2007Maria Giovanna Riparbelli Abstract Dynamic alterations in the spatial organization of cytoskeletal elements constitute a prominent morphological feature of the early, syncytial stages of embryogenesis in Drosophila. Here, we describe and characterize the dynamic behavior of cytoplasmic, subcortical microfilaments, which form a series of nucleus-associated structures, at different phases of the simultaneous nuclear division cycles characteristic of early Drosophila embryos. Remodeling of the cytoplasmic microfilament arrays takes place in parallel to the established cyclic reorganization of cortical microfilament structures. We provide evidence that the cortical and subcortical microfilament populations organize independently of each other, and in response to distinct instructive cues. Specifically, formation of subcortical microfilament structures appears to rely on, and spatially mirror, the organization of polarized microtubule arrays, while cortical microfilament restructuring constitutes a centrosome-dependent process. Genetic analysis identifies a requirement for SCAR, a key mediator of Arp2/3-based microfilament dynamics, in organization of subcortical microfilament structures. Developmental Dynamics 236:662,670, 2007. © 2007 Wiley-Liss, Inc. [source] A cognitive and affective pattern in posterior fossa strokes in children: a case seriesDEVELOPMENTAL MEDICINE & CHILD NEUROLOGY, Issue 7 2010MANOELLE KOSSOROTOFF Aim, Posterior fossa strokes account for about 10% of ischaemic strokes in children. Although motor and dysautonomic symptoms are common, to our knowledge cognitive and affective deficits have not been described in the paediatric literature. Our aim, therefore, was to describe these symptoms and deficits. Method, In a retrospective study, we included all cases of posterior fossa strokes in children occurring at a single centre between 2005 and 2007, and investigated cognitive and affective deficits. Results, Five males aged 3 to 14 years met the inclusion criteria. They all presented very early with mood disturbances: outbursts of laughter and/or crying and alternating agitation or prostration that disappeared spontaneously within a few days. Persistent cognitive deficits were also diagnosed in all five: initial mutism, then anomia, followed by comprehension deficiency and deficiencies of planning ability, visual,spatial organization, and attention. Despite early and intensive rehabilitation, recovery from these cognitive deficits was slow and sometimes incomplete, and on follow-up they proved to be more disabling than the motor symptoms. Interpretation, These findings are similar to the cerebellar cognitive affective syndrome described in adults, and quite similar to the language and affective deficits observed in children after surgery for posterior fossa tumour. This is consistent with the role of the cerebellum and brainstem in affective and cognitive processes from early development. [source] Some aspects of spiralian developmentACTA ZOOLOGICA, Issue 1 2010Claus Nielsen Abstract Nielsen, C. 2010. Some aspects of spiralian development. ,Acta Zoologica (Stockholm) 91: 20,28 Spiralian development is not only a characteristic early cleavage pattern, with shifting orientations of the cleavage planes, but also highly conserved cell lineages, where the origin of several organs can be traced back to identifiable cells in the lineage. These patterns are well documented in annelids, molluscs, nemertines, and platyhelminths and are considered ancestral of a bilaterian clade including these phyla. Spiral cleavage has not been documented in ecdysozoans, and no trace of the spiral development pattern is seen in phoronids and brachiopods. Origin of the spatial organization in spiralian embryos is puzzling, but much of the information appears to be encoded in the developing oocyte. Fertilization and "pseudofertilization" apparently provides the information defining the secondary, anterior-posterior body axis in many species. The central nervous system consists of three components: an apical organ, derived from the apical blastomeres 1a111 -1d111, which degenerates before or at metamorphosis; the cerebral ganglia derived from other blastomeres of the first micromere quartet and retained in the adult as a preoral part of the brain; and the originally circumblastoporal nerve cord, which has become differentiated into a perioral part of the brain, the paired or secondarily fused ventral nerve cords, and a small perianal nerve ring. [source] Effects of spatially structured vegetation patterns on hillslope erosion in a semiarid Mediterranean environment: a simulation studyEARTH SURFACE PROCESSES AND LANDFORMS, Issue 2 2005Matthias Boer Abstract A general trend of decreasing soil loss rates with increasing vegetation cover fraction is widely accepted. Field observations and experimental work, however, show that the form of the cover-erosion function can vary considerably, in particular for low cover conditions that prevail on arid and semiarid hillslopes. In this paper the structured spatial distribution of the vegetation cover and associated soil attributes is proposed as one of the possible causes of variation in cover,erosion relationships, in particular in dryland environments where patchy vegetation covers are common. A simulation approach was used to test the hypothesis that hillslope discharge and soil loss could be affected by variation in the spatial correlation structure of coupled vegetation cover and soil patterns alone. The Limburg Soil Erosion Model (LISEM) was parameterized and verified for a small catchment with discontinuous vegetation cover at Rambla Honda, SE Spain. Using the same parameter sets LISEM was subsequently used to simulate water and sediment fluxes on 1 ha hypothetical hillslopes with simulated spatial distributions of vegetation and soil parameters. Storms of constant rainfall intensity in the range of 30,70 mm h,1 and 10,30 min duration were applied. To quantify the effect of the spatial correlation structure of the vegetation and soil patterns, predicted discharge and soil loss rates from hillslopes with spatially structured distributions of vegetation and soil parameters were compared with those from hillslopes with spatially uniform distributions. The results showed that the spatial organization of bare and vegetated surfaces alone can have a substantial impact on predicted storm discharge and erosion. In general, water and sediment yields from hillslopes with spatially structured distributions of vegetation and soil parameters were greater than from identical hillslopes with spatially uniform distributions. Within a storm the effect of spatially structured vegetation and soil patterns was observed to be highly dynamic, and to depend on rainfall intensity and slope gradient. Copyright © 2005 John Wiley & Sons, Ltd. [source] English in classrooms: only write down what you need to know: annotation for what?ENGLISH IN EDUCATION, Issue 1 2005Dr Carey Jewitt Abstract The annotation of texts in the school English classroom is central to the curriculum, examination and the history of English as a school subject. In this paper we explore ,the way it is done' across two different classrooms. We focus on the relationship between official definitions of annotation offered by national policies and examination syllabuses and its actualization in particular classrooms. The article takes a multimodal approach: attending to all modes of representation and communication in the teaching of English including image, gesture, gaze and the spatial organization of the classroom. [source] Niche heterogeneity determines bacterial community structure in the termite gut (Reticulitermes santonensis)ENVIRONMENTAL MICROBIOLOGY, Issue 7 2005Hong Yang Summary Differences in microenvironment and interactions of microorganisms within and across habitat boundaries should influence structure and diversity of the microbial communities within an ecosystem. We tested this hypothesis using the well characterized gut tract of the European subterranean termite Reticulitermes santonensis as a model. By cloning and sequencing analysis and molecular fingerprinting (terminal restriction fragment length polymorphism), we characterized the bacterial microbiota in the major intestinal habitats , the midgut, the wall of the hindgut paunch, the hindgut fluid and the intestinal protozoa. The bacterial community was very diverse (> 200 ribotypes) and comprised representatives of several phyla, including Firmicutes (mainly clostridia, streptococci and Mycoplasmatales -related clones), Bacteroidetes, Spirochaetes and a number of Proteobacteria, all of which were unevenly distributed among the four habitats. The largest group of clones fell into the so-called Termite group 1 (TG-1) phylum, which has no cultivated representatives. The majority of the TG-1 clones were associated with the protozoa and formed two phylogenetically distinct clusters, which consisted exclusively of clones previously retrieved from the gut of this and other Reticulitermes species. Also the other clones represented lineages of microorganisms that were exclusively recovered from the intestinal tract of termites. The termite specificity of these lineages was underscored by the finding that the closest relatives of the bacterial clones obtained from R. santonensis were usually derived also from the most closely related termites. Overall, differences in diversity between the different gut habitats and the uneven distribution of individual phylotypes support conclusively that niche heterogeneity is a strong determinant of the structure and spatial organization of the microbial community in the termite gut. [source] Detection of the Sexual Identity of Conspecifics through Volatile Chemical Signals in a Territorial SalamanderETHOLOGY, Issue 3 2007Benjamin J. Dantzer Territorial red-backed salamanders (Plethodon cinereus) have been shown to use nonvolatile chemical signals in both territorial defense and to convey a variety of information to conspecifics. We investigated whether or not red-backed salamanders could determine the sexual identity of conspecifics through volatile chemical signals, and we explored their use in the context of territorial defense. We exposed male and female red-backed salamanders to four experimental treatments (i.e. filter papers that had been scent marked by male or female conspecifics for 1 and 5 d) and two control treatments (i.e. unscented filter papers for 1 and 5 d tests). The focal salamanders were prevented from physically accessing the scent marked filter papers and, presumably, some of the substrate scent marks had volatile components that were detected and interpreted by the focal salamanders. Both male and female red-backed salamanders spent significantly more time in threat displays when they were exposed to volatile chemical signals from same-sex conspecifics than they did toward similar signals from opposite-sex conspecifics. A similar statistical pattern was observed for the amount of chemosensory sampling exhibited by focal red-backed salamanders. From these results, we infer that red-backed salamanders can determine the sexual identity of conspecifics through volatile chemical signals, some of which may be used in territorial defense. Further, such airborne pheromones may influence the spatial organization of salamander territories on the forest floor. [source] Pre- and postsynaptic GABAA receptors at reciprocal dendrodendritic synapses in the olfactory bulbEUROPEAN JOURNAL OF NEUROSCIENCE, Issue 11 2004Patrizia Panzanelli Abstract Presynaptic ionotropic receptors are important regulators of synaptic function; however, little is known about their organization in the presynaptic membrane. We show here a different spatial organization of presynaptic and postsynaptic GABAA receptors at reciprocal dendrodendritic synapses between mitral and granule cells in the rat olfactory bulb. Using postembedding electron microscopy, we have found that mitral cell dendrites express GABAA receptors at postsynaptic specializations of symmetric (GABAergic) synapses, as well as at presynaptic sites of asymmetric (glutamatergic) synapses. Analysis of the subsynaptic distribution of gold particles revealed that in symmetric synapses GABAA receptors are distributed along the entire postsynaptic membrane, whereas in asymmetric synapses they are concentrated at the edge of the presynaptic specialization. To assess the specificity of immunogold labelling, we analysed the olfactory bulbs of mutant mice lacking the ,1 subunit of GABAA receptors. We found that in wild-type mice ,1 subunit immunoreactivity was similar to that observed in rats, whereas in knockout mice the immunolabelling was abolished. These results indicate that in mitral cell dendrites GABAA receptors are distributed in a perisynaptic domain that surrounds the presynaptic specialization. Such presynaptic receptors may be activated by spillover of GABA from adjacent inhibitory synapses and modulate glutamate release, thereby providing a novel mechanism regulating dendrodendritic inhibition in the olfactory bulb. [source] Molecular-feature domains with posterodorsal,anteroventral polarity in the symmetrical sensory maps of the mouse olfactory bulb: mapping of odourant-induced Zif268 expressionEUROPEAN JOURNAL OF NEUROSCIENCE, Issue 10 2002Koichiro Inaki Abstract Individual glomeruli in the mammalian olfactory bulb presumably represent a single type of odourant receptor. Thus, the glomerular sheet provides odourant receptor maps at the surface of the olfactory bulb. To understand the basic spatial organization of the olfactory sensory maps, we first compared the spatial distribution of odourant-induced responses measured by the optical imaging of intrinsic signals with that detected immunohistochemically by expressions of Zif268, one of the immediate early gene products in juxtaglomerular cells. In the dorsal surface of the bulb, we detected a clear correlation in the spatial pattern between these responses. In addition, the molecular-feature domains and their polarities (spatial shifts of responses with an increase in carbon chain length) that were defined by the optical imaging method could be also detected by the Zif268 mapping method. We then mapped the Zif268 signals over the entire olfactory bulb using a homologous series of fatty acids and aliphatic alcohols as stimulus odourants. We superimposed the Zif268 signals onto the standard unrolled map with the help of cell adhesion molecule compartments. Each odourant typically elicited two pairs of clusters of dense Zif268 signals. The results showed that molecular-feature domains and their polarities were arranged symmetrically at stereotypical positions in a mirror-image fashion between the lateral and the medial sensory maps. The polarity of each domain was roughly in parallel with the posterodorsal,anteroventral axis that was defined by the cell adhesion molecule compartments. These results suggest that the molecular-feature domain with its fixed polarity is one of the basic structural units in the spatial organization of the odourant receptor maps in the olfactory bulb. [source] SPATIAL AND TEMPORAL DYNAMICS IN A SEXUAL SELECTION MOSAICEVOLUTION, Issue 4 2008Thomas P. Gosden Selective regimes and phenotypic optima could either change smoothly and in a clinal fashion or be spatially organized in a more unpredictable mosaic pattern over the geographic landscape. When natural or sexual selection is driven by intra- or interspecific biotic interactions, fine-grained spatial variation in selective regimes could result in selection mosaics rather than clinal variation in selection. We investigated temporal variation and spatial organization in sexual selection on male body size along an ecological coastal-inland gradient of a polymorphic damselfly Ischnura elegans. Body size increased in a clinal fashion along this gradient: animals were smaller in size at the coast, but became larger in the inland areas. In contrast, the sexual selection regimes on male body size showed evidence of more fine-grained spatial organization with no evidence for a clinal pattern and low spatial autocorrelations between populations. These spatially fine-grained sexual selection regimes varied in sign and magnitude and were driven by a combination of the densities of heritable female color morphs and local female body sizes. We suggest that the spatial organization of the selective regimes can be interpreted as a sexual selection mosaic that is influenced by highly localized density- and frequency-dependent social interactions. [source] A geomorphic template for the analysis of lake districts applied to the Northern Highland Lake District, Wisconsin, U.S.A.FRESHWATER BIOLOGY, Issue 3 2000JoaN. L. Riera 1. We tested the degree to which a lake's landscape position constrains the expression of limnological features and imposes a characteristic spatial pattern in a glacial lake district, the Northern Highland Lake District in north-central Wisconsin. 2. We defined lake order as a metric to analyze the effect of landscape position on limnological features. Lake order, analogous to stream order, is based solely on geographical information and is simple to measure. 3. We examined the strength of the relationship between lake order and a set of 25 variables, which included measures of lake morphometry, water optical properties, major ions, nutrients, biology, and human settlement patterns. 4. Lake order explained a significant fraction of the variance of 21 of the 25 variables tested with ANOVA. The fraction of variance explained varied from 12% (maximum depth) to 56% (calcium concentration). The variables most strongly related to lake order were: measures of lake size and shape, concentrations of major ions (except sulfate) and silica, biological variables (chlorophyll concentration, crayfish abundance, and fish species richness), and human-use variables (density of cottages and resorts). Lake depth, water optical properties, and nutrient concentrations (other than silica) were poorly associated with lake order. 5. Potential explanations for a relationship with lake order differed among variables. In some cases, we could hypothesize a direct link. For example, major ion concentration is a function of groundwater input, which is directly related to lake order. We see these as a direct influence of the geomorphic template left by the retreat of the glacier that led to the formation of this lake district. 6. In other cases, a set of indirect links was hypothesized. For example, the effect of lake order on lake size, water chemistry, and lake connectivity may ultimately explain the relation between lake order and fish species richness. We interpret these relationships as the result of constraints imposed by the geomorphic template on lake development over the last 12 000 years. 7. By identifying relationships between lake characteristics and a measure of landscape position, and by identifying geomorphologic constraints on lake features and lake evolution, our analysis explains an important aspect of the spatial organization of a lake district. [source] THE AIRPORT HOTEL AS BUSINESS SPACEGEOGRAFISKA ANNALER SERIES B: HUMAN GEOGRAPHY, Issue 3 2009Donald McNeill ABSTRACT. This article seeks to contribute to debates about the mobile nature of contemporary economic practice, through a discussion of some key themes in the evolution of airport hotels as business spaces. It argues that despite being emblematic of a hypermobile business elite, the nature of hotels as business spaces requires careful unpacking. The article begins by discussing the evolution of the airport hotel, charting the shift from basic lodging standards to recent developments of five star airport hotels. It then seeks to explain the locational geographies of airport hotel development, in response to these new trends. Finally, the article describes how the business traveller is conceived of and (speculatively) catered for by airport hotel operators and designers within a discourse of connectivity, before providing some counter-examples of how such claims fail to address the hotel's place within the complexity of airport spatial organization. [source] A CITY IN MOTION: TIME-SPACE ACTIVITY AND MOBILITY PATTERNS OF SUBURBAN INHABITANTS AND THE STRUCTURATION OF THE SPATIAL ORGANIZATION OF THE PRAGUE METROPOLITAN AREAGEOGRAFISKA ANNALER SERIES B: HUMAN GEOGRAPHY, Issue 2 2007Jakub Novák ABSTRACT. This contribution attempts to reveal the relations between new suburban areas and other parts of the Prague metropolitan area by investigating the time-space activity and mobility patterns of the inhabitants of newly built suburban districts. The focus on some aspects of the everyday life of people in new suburbs helps us to identify the impact of suburbanization on the changing geography of the metropolitan region and to better understand how the spatial organization of the Prague metropolitan area is produced, reproduced and transformed. We use several interrelated concepts, which serve the theoretical foundation of our work, namely time geography, structuration theory and the post-communist city. The empirical data utilized are primarily based on 262 diaries completed by eighty-eight individuals from thirty-eight households, accompanied by household questionnaires and interviews with the heads of households. The research confirmed the implicit, generally unspoken view that new suburbs in the Prague metropolitan region are heavily dependent on the core of the metropolitan area for the provision of jobs and services. However, newly built suburban shopping facilities to some extent disrupt this pattern, keeping some daily activities of inhabitants within the suburban zone. In addition to empirical observations, the key purpose of this contribution has been to discuss and apply time geography concepts and methods to the research of urban restructuring, and to understand the structuration of metropolitan spatial organization. [source] Changes in the expression of plasma membrane calcium extrusion systems during the maturation of hippocampal neuronsHIPPOCAMPUS, Issue 1 2006Sertac N. Kip Abstract Spatial and temporal control of intracellular calcium signaling is essential for neuronal development and function. The termination of local Ca2+ signaling and the maintenance of basal Ca2+ levels require specific extrusion systems in the plasma membrane. In rat hippocampal neurons (HNs) developing in vitro, transcripts for all isoforms of the plasma membrane Ca2+ pump and the Na/Ca2+ exchanger, and the major nonphotoreceptor Na+/Ca2+,K+ exchangers (NCKX) were strongly upregulated during the second week in culture. Upregulation of plasma membrane calcium ATPases (PMCAs)1, 3, and 4 mRNA coincided with a splice shift from the ubiquitous b-type to the neuron-specific a-type with altered calmodulin regulation. Expression of all PMCA isoforms increased over 5-fold during the first 2 weeks. PMCA immunoreactivity was initially concentrated in the soma and growth cones of developing HNs. As the cells matured, PMCAs concentrated in the dendritic membrane and often colocalized with actin-rich dendritic spines in mature neurons. In the developing rat hippocampal CA1 region, immunohistochemistry confirmed the upregulation of all PMCAs and showed that by the end of the second postnatal week, PMCAs1, 2, and 3 were concentrated in the neuropil, with less intense staining of cell bodies in the pyramidal layer. PMCA4 staining was restricted to a few cells showing intense labeling of the cell periphery and neurites. These results establish that all major Ca2+ extrusion systems are strongly upregulated in HNs during the first 2 weeks of postnatal development. The overall increase in Ca2+ extrusion systems is accompanied by changes in the expression and cellular localization of different isoforms of the Ca2+ pumps and exchangers. The accumulation of PMCAs in dendrites and dendritic spines coincides with the functional maturation in these neurons, suggesting the importance of the proper spatial organization of Ca2+ extrusion systems for synaptic function and development. © 2005 Wiley-Liss, Inc. [source] Visualizing thymocyte motility using 2-photon microscopyIMMUNOLOGICAL REVIEWS, Issue 1 2003Ellen A. Robey Summary:, Our view of a thymocyte based on its behavior in tissue culture and appearance in fixed tissue sections was of a round sessile cell. Its travel through the thymus might occur slowly, perhaps even passively, leaving it in contact with the support cells that happened to be in its immediate environment. However, when we got our first look at the behavior of thymocytes in a 3D cellular stromal cell environment, that picture changed dramatically. Instead we found that thymocytes are actively crawling, allowing them to explore their environment over relatively long distances and interact with peptide-major histocompatibility complex (pMHC)-bearing thymic stromal cells in both dynamic and stable modes. In this review, we discuss the implications of thymocyte motility for T-cell repertoire selection and for the mechanisms that determine the spatial organization of thymocyte subsets within the thymus. [source] Active Crohn's disease and ulcerative colitis can be specifically diagnosed and monitored based on the biostructure of the fecal floraINFLAMMATORY BOWEL DISEASES, Issue 2 2008Alexander Swidsinski MD Abstract Background: The intestinal microflora is important in the pathogenesis of inflammatory bowel disease (IBD). The impact of its spatial organization on health and disease is unknown. Methods: We investigated sections of paraffin-embedded punched fecal cylinders. Fluctuations in spatial distribution of 11 bacterial groups were monitored in healthy subjects (n = 32), patients with IBD (n = 204), and other gastrointestinal diseases (n = 186) using fluorescence in situ hybridization (FISH). Results: The microbial structure differed in patients with Crohn's disease (CD), ulcerative colitis (UC), and healthy and disease controls. The profiles of CD and UC were distinctly opposite in 6 of 11 FISH probes used. Most prominent were a depletion of Faecalibacterium prausnitzii (Fprau<1 × 109/mL) with a normal leukocyte count in CD and a massive increase of leukocytes in the fecal-mucus transition zone (>30 leukocytes/104,m2) with high Fprau in patients with UC. These 2 features alone enabled the recognition of active CD (Crohn's Disease Activity Index [CDAI] >150) or UC (Clinical Activity Index [CAI] >3) with 79%/80% sensitivity and 98%/100% specificity. The mismatch in the sensitivity was mainly due to overlap between single IBD entities, and the specificity was exclusively due to the similarity of Crohn's and celiac disease. When inflammatory bowel disease (IBD) patients were pooled the sensitivity was 100% for severe disease, 84% for moderate activity, 72% for IBD with ,12 months remission, and 24% for IBD with >12 months remission. Conclusions: The fecal flora is highly structured and spatially organized. Diagnosing IBD and monitoring disease activity can be performed based on analysis of punched fecal cylinders independent from the patient's complaints. (Inflamm Bowel Dis 2007) [source] Precipitation characteristics of the Eurasian Arctic drainage systemINTERNATIONAL JOURNAL OF CLIMATOLOGY, Issue 11 2003Mark C. Serreze Abstract This study examines characteristics of precipitation over the major watersheds of the Eurasian Arctic drainage system over the period 1960,92. In addition to the Ob, Yenisey and Lena (the three largest drainage systems), we examine the combined Kolyma,Indigirka in eastern Eurasia. Each basin exhibits approximately symmetric mean annual cycles of monthly total precipitation and daily event size, with winter minima and July maxima. These are strikingly similar to the annual cycles of total column water vapour (precipitable water), which fundamentally reflects the control on saturation vapour pressure by temperature. Effective precipitation mechanisms exist in all seasons. However, because of the long distance from strong moisture sources (continentality), precipitation tends to follow the seasonality in column water vapour. An effective contrast is presented for the Iceland sector. Here, the annual cycle of precipitation is tied not to the seasonality in column water vapour, but to the stronger precipitation-generating mechanisms in winter. Hence, the annual cycles of precipitation and column water vapour in this region oppose each other. Mean winter precipitation over the Eurasian watersheds is primarily driven by a modest convergence of water vapour. Whereas precipitation peaks in summer, the mean flux convergence exhibits a general minimum (negative in the Ob). Summer precipitation is hence primarily associated with surface evaporation. A strong role of convection is supported from consideration of static stability, the fairly weak spatial organization of precipitation totals and results from prior studies. On daily time scales, the largest basin-averaged precipitation events, for both summer and winter, are allied with synoptic-scale forcing. This is seen in relationships with cyclone frequency, and patterns of 500 hPa height, vertical motion and the 700 hPa vapour flux. The relative frequency of four 500 hPa synoptic types captures the basic time series structures of precipitation. Copyright © 2003 Royal Meteorological Society [source] Effects of culling on badger Meles meles spatial organization: implications for the control of bovine tuberculosisJOURNAL OF APPLIED ECOLOGY, Issue 1 2006ROSIE WOODROFFE Summary 1The incidence of bovine tuberculosis (TB) in British cattle has risen markedly over the last two decades. Failure to control the disease in cattle has been linked to the persistence of a reservoir of infection in European badgers Meles meles, a nationally protected species. Although badger culling has formed a component of British TB control policy for many years, a recent large-scale randomized field experiment found that TB incidence in cattle was no lower in areas subject to localized badger culling than in nearby areas where no experimental culls occurred. Indeed, analyses indicated that cattle incidence was higher in culled areas. 2One hypothesis advanced to explain this pattern is that localized culling disrupted badgers' territorial behaviour, potentially increasing the rate of contact between cattle and infected badgers. This study evaluated this hypothesis by investigating badger activity and spatial organization in 13 study areas subjected to different levels of culling. Badger home ranges were mapped by feeding colour-marked baits at badger dens and measuring the geographical area in which colour-marked faeces were retrieved. 3Badger home ranges were consistently larger in culling areas. Moreover, in areas not subjected to culling, home range sizes increased with proximity to the culling area boundary. Patterns of overlap between home ranges were also influenced by culling. 4Synthesis and applications. This study demonstrates that culling badgers profoundly alters their spatial organization as well as their population density. These changes have the potential to influence contact rates between cattle and badgers, both where culls occur and on adjoining land. These results may help to explain why localized badger culling appears to have failed to control cattle TB, and should be taken into account in determining what role, if any, badger culling should play in future control strategies. [source] The effects of osmotic stress on the structure and function of the cell nucleusJOURNAL OF CELLULAR BIOCHEMISTRY, Issue 3 2010John D. Finan Abstract Osmotic stress is a potent regulator of the normal function of cells that are exposed to osmotically active environments under physiologic or pathologic conditions. The ability of cells to alter gene expression and metabolic activity in response to changes in the osmotic environment provides an additional regulatory mechanism for a diverse array of tissues and organs in the human body. In addition to the activation of various osmotically- or volume-activated ion channels, osmotic stress may also act on the genome via a direct biophysical pathway. Changes in extracellular osmolality alter cell volume, and therefore, the concentration of intracellular macromolecules. In turn, intracellular macromolecule concentration is a key physical parameter affecting the spatial organization and pressurization of the nucleus. Hyper-osmotic stress shrinks the nucleus and causes it to assume a convoluted shape, whereas hypo-osmotic stress swells the nucleus to a size that is limited by stretch of the nuclear lamina and induces a smooth, round shape of the nucleus. These behaviors are consistent with a model of the nucleus as a charged core/shell structure pressurized by uneven partition of macromolecules between the nucleoplasm and the cytoplasm. These osmotically-induced alterations in the internal structure and arrangement of chromatin, as well as potential changes in the nuclear membrane and pores are hypothesized to influence gene transcription and/or nucleocytoplasmic transport. A further understanding of the biophysical and biochemical mechanisms involved in these processes would have important ramifications for a range of fields including differentiation, migration, mechanotransduction, DNA repair, and tumorigenesis. J. Cell. Biochem. 109: 460,467, 2010. © 2009 Wiley-Liss, Inc. [source] Primary mouse embryonic fibroblasts: A model of mesenchymal cartilage formation,JOURNAL OF CELLULAR PHYSIOLOGY, Issue 3 2004Christopher J. Lengner Cartilage formation is an intricate process that requires temporal and spatial organization of regulatory factors in order for a mesenchymal progenitor cell to differentiate through the distinct stages of chondrogenesis. Gene function during this process has best been studied by analysis of in vivo cartilage formation in genetically altered mouse models. Mouse embryonic fibroblasts (MEFs) isolated from such mouse models have been widely used for the study of growth control and DNA damage response. Here, we address the potential of MEFs to undergo chondrogenic differentiation. We demonstrate for the first time that MEFs can enter and complete the program of chondrogenic differentiation ex vivo, from undifferentiated progenitor cells to mature, hypertrophic chondrocytes. We show that chondrogenic differentiation can be induced by cell,cell contact or BMP-2 treatment, while in combination, these conditions synergistically enhance chondrocyte differentiation resulting in the formation of 3-dimensional (3-D) cartilaginous tissue ex vivo. Temporal expression profiles of pro-chondrogenic transcription factors Bapx1 and Sox9 and cartilaginous extracellular matrix (ECM) proteins Collagen Type II and X (Coll II and Coll X) demonstrate that the in vivo progression of chondrocyte maturation is recapitulated in the MEF model system. Our findings establish the MEF as a powerful tool for the generation of cartilaginous tissue ex vivo and for the study of gene function during chondrogenesis. © 2004 Wiley-Liss, Inc. [source] Effects of aging and gender on the spatial organization of nuclei in single human skeletal muscle cellsAGING CELL, Issue 5 2010Alexander Cristea Summary The skeletal muscle fibre is a syncitium where each myonucleus regulates the gene products in a finite volume of the cytoplasm, i.e., the myonuclear domain (MND). We analysed aging- and gender-related effects on myonuclei organization and the MND size in single muscle fibres from six young (21,31 years) and nine old men (72,96 years), and from six young (24,32 years) and nine old women (65,96 years), using a novel image analysis algorithm applied to confocal images. Muscle fibres were classified according to myosin heavy chain (MyHC) isoform expression. Our image analysis algorithm was effective in determining the spatial organization of myonuclei and the distribution of individual MNDs along the single fibre segments. Significant linear relations were observed between MND size and fibre size, irrespective age, gender and MyHC isoform expression. The spatial organization of individual myonuclei, calculated as the distribution of nearest neighbour distances in 3D, and MND size were affected in old age, but changes were dependent on MyHC isoform expression. In type I muscle fibres, average NN-values were lower and showed an increased variability in old age, reflecting an aggregation of myonuclei in old age. Average MND size did not change in old age, but there was an increased MND size variability. In type IIa fibres, average NN-values and MND sizes were lower in old age, reflecting the smaller size of these muscle fibres in old age. It is suggested that these changes have a significant impact on protein synthesis and degradation during the aging process. [source] Directing traffic in neural cells: determinants of receptor tyrosine kinase localization and cellular responsesJOURNAL OF NEUROCHEMISTRY, Issue 6 2008Robert J. Romanelli Abstract The trafficking of receptor tyrosine kinases (RTKs) to distinct subcellular locations is essential for the specificity and fidelity of signal transduction and biological responses. This is particularly important in the PNS and CNS in which RTKs mediate key events in the development and maintenance of neurons and glia through a wide range of neural processes, including survival, proliferation, differentiation, neurite outgrowth, and synaptogenesis. The mechanisms that regulate the targeting of RTKs to their subcellular destinations for appropriate signal transduction, however, are still elusive. In this review, we discuss evidence for the spatial organization of signaling machinery into distinct subcellular compartments, as well as the role for ligand specificity, receptor sorting signals, and lipid raft microdomains in RTK targeting and the resultant cellular responses in neural cells. [source] Localization of synaptic proteins involved in neurosecretion in different membrane microdomainsJOURNAL OF NEUROCHEMISTRY, Issue 3 2007Elena Taverna Abstract A number of proteins and signalling molecules modulate voltage-gated calcium channel activity and neurosecretion. As recent findings have indicated the presence of Cav2.1 (P/Q-type) channels and soluble N -ethyl-maleimide-sensitive fusion protein attachment protein receptors (SNAREs) in the cholesterol-enriched microdomains of neuroendocrine and neuronal cells, we investigated whether molecules known to modulate neurosecretion, such as the heterotrimeric G proteins and neuronal calcium sensor-1 (NCS-1), are also localized in these microdomains. After immuno-isolation, flotation gradients from Triton X-100-treated synaptosomal membranes revealed the presence of different detergent-resistant membranes (DRMs) containing proteins of the exocytic machinery (Cav2.1 channels and SNAREs) or NCS-1; both DRM subtypes contained aliquots of heterotrimeric G protein subunits and phosphatidylinositol-4,5-bisphosphate. In line with the biochemical data, confocal imaging of immunolabelled membrane sheets revealed the localization of SNARE proteins and NCS-1 in different dot-like structures. This distribution was largely impaired by treatment with methyl-,-cyclodextrin, thus suggesting the localization of all three proteins in cholesterol-dependent domains. Finally, bradykinin (which is known to activate the NCS-1 pathway) caused a significant increase in NCS-1 in the DRMs. These findings suggest that different membrane microdomains are involved in the spatial organization of the complex molecular network that converges on calcium channels and the secretory machinery. [source] Induction of a neoarthrosis by precisely controlled motion in an experimental mid-femoral defectJOURNAL OF ORTHOPAEDIC RESEARCH, Issue 3 2002Dennis M. Cullinane Bone regeneration during fracture healing has been demonstrated repeatedly, yet the regeneration of articular cartilage and joints has not yet been achieved. It has been recognized however that the mechanical environment during fracture healing can be correlated to the contributions of either the endochondral or intramembranous processes of bone formation, and to resultant tissue architecture. Using this information, the goal of this study was to test the hypothesis that induced motion can directly regulate osteogenic and chondrogenic tissue formation in a rat mid-femoral bone defect and thereby influence the anatomical result. Sixteen male Sprague Dawley rats (400 ± 20 g) underwent production of a mid-diaphyseal, non-critical sized 3.0 mm segmental femoral defect with rigid external fixation using a custom designed four pin fixator. One group of eight animals represented the controls and underwent surgery and constant rigid fixation. In the treatment group the custom external fixator was used to introduce daily interfragmentary bending strain in the eight treatment animals (12°s angular excursion), with a hypothetical symmetrical bending load centered within the gap. The eight animals in the treatment group received motion at 1.0 Hz, for 10 min a day, with a 3 days on, one day off loading protocol for the first two weeks, and 2 days on, one day off for the remaining three weeks. Data collection included histological and immunohistological identification of tissue types, and mean collagen fiber angles and angular conformity between individual fibers in superficial, intermediate, and deep zones within the cartilage. These parameters were compared between the treatment group, rat knee articular cartilage, and the control group as a structural outcome assessment. After 35 days the control animals demonstrated varying degrees of osseous union of the defect with some animals showing partial union. In every individual within the mechanical treatment group the defect completely failed to unite. Bony arcades developed in the experimental group, capping the termini of the bone segments on both sides of the defect in four out of six animals completing the study. These new structures were typically covered with cartilage, as identified by specific histological staining for Type II collagen and proteoglycans. The distribution of collagen within analogous superficial, intermediate, and deep zones of the newly formed cartilage tissue demonstrated preferred fiber angles consistent with those seen in articular cartilage. Although not resulting in complete joint development, these neoarthroses show that the induced motion selectively controlled the formation of cartilage and bone during fracture repair, and that it can be specifically directed. They further demonstrate that the spatial organization of molecular components within the newly formed tissue, at both microanatomical and gross levels, are influenced by their local mechanical environment, confirming previous theoretical models. © 2002 Orthopaedic Research Society. Published by Elsevier Science Ltd. All rights reserved. [source] The effects of spacing and titles on judgments of the effectiveness of structured abstractsJOURNAL OF THE AMERICAN SOCIETY FOR INFORMATION SCIENCE AND TECHNOLOGY, Issue 14 2007James Hartley Previous research assessing the effectiveness of structured abstracts has been limited in two respects. First, when comparing structured abstracts with traditional ones, investigators usually have rewritten the original abstracts, and thus confounded changes in the layout with changes in both the wording and the content of the text. Second, investigators have not always included the title of the article together with the abstract when asking participants to judge the quality of the abstracts, yet titles alert readers to the meaning of the materials that follow. The aim of this research was to redress these limitations. Three studies were carried out. Four versions of each of four abstracts were prepared. These versions consisted of structured/traditional abstracts matched in content, with and without titles. In Study 1, 64 undergraduates each rated one of these abstracts on six separate rating scales. In Study 2, 225 academics and research workers rated the abstracts electronically, and in Study 3, 252 information scientists did likewise. In Studies 1 and 3, the respondents rated the structured abstracts significantly more favorably than they did the traditional ones, but the presence or absence of titles had no effect on their judgments. In Study 2, no main effects were observed for structure or for titles. The layout of the text, together with the subheadings, contributed to the higher ratings of effectiveness for structured abstracts, but the presence or absence of titles had no clear effects in these experimental studies. It is likely that this spatial organization, together with the greater amount of information normally provided in structured abstracts, explains why structured abstracts are generally judged to be superior to traditional ones. [source] GATED COMMUNITIES AND SPATIAL INEQUALITYJOURNAL OF URBAN AFFAIRS, Issue 2 2007ELENA VESSELINOV ABSTRACT:,In this article we analyze gated communities as a nexus of social and spatial relations within the context of urban inequality. We apply Tickamyer's (2000) sociological framework for incorporating space into the study of inequality, which allows us to substantiate the arguments that the process of gating increases urban inequality. The contributions of this article are three: (1) We generate a new systematic theoretical approach toward the study of gated communities, which we consider as middle range theory; (2) We argue that gated communities reproduce the existing levels of social stratification and that they also define a new, permanent differentiation order in the spatial organization of cities in the United States (in this respect we also arrive at six hypotheses, which can be tested in future research); (3) We introduce the term "gating machine," where the combination of the interests and actions of local governments, real estate developers, the media, and consumers suggest that prevailing structural conditions assure the future proliferation of gated communities. [source] | |||||||||||||||||||||||||||||||||||||||||||