scholarly journals Role of malnutrition and parasite infections in the spatial variation in children’s anaemia risk in northern Angola

2013 ◽  
Vol 7 (2) ◽  
pp. 341 ◽  
Author(s):  
Ricardo J. Soares Magalhães ◽  
Antonio Langa ◽  
João Mário Pedro ◽  
José Carlos Sousa-Figueiredo ◽  
Archie C.A. Clements ◽  
...  
Keyword(s):  
Spatial Variation ◽  
Parasite Infections

Consistent patterns of trophic niche specialization in host populations infected with a non-native copepod parasite

Parasitology ◽  
2017 ◽  
Vol 144 (7) ◽  
pp. 945-953 ◽  
Author(s):  
J. PEGG ◽  
D. ANDREOU ◽  
C. F. WILLIAMS ◽  
J. R. BRITTON
Keyword(s):  
Trophic Niche ◽  
Isotopic Niche ◽  
Trophic Specialization ◽  
Generalist Species ◽  
Copepod Parasite ◽  
Niche Specialization ◽  
Parasite Infections ◽  
Native Parasite ◽  
Fish Hosts

SUMMARYPopulations of generalist species often comprise of smaller sub-sets of relatively specialized individuals whose niches comprise small sub-sets of the overall population niche. Here, the role of parasite infections in trophic niche specialization was tested using five wild fish populations infected with the non-native parasite Ergasilus briani, a copepod parasite with a direct lifecycle that infects the gill tissues of fish hosts. Infected and uninfected fishes were sampled from the same habitats during sampling events. Prevalence in the host populations ranged between 16 and 67%, with parasite abundances of up to 66 parasites per fish. Although pathological impacts included hyperplasia and localized haemorrhaging of gill tissues, there were no significant differences in the length, weight and condition of infected and uninfected fishes. Stable isotope analyses (δ13C, δ15N) revealed that the trophic niche of infected fishes, measured as standard ellipse area (i.e. the isotopic niche), was consistently and significantly smaller compared with uninfected conspecifics. These niches of infected fishes always sat within that of uninfected fish, suggesting trophic specialization in hosts. These results suggested trophic specialization is a potentially important non-lethal consequence of parasite infection that results from impaired functional traits of the host.

Property Relations and Landlordism—a Realist Approach

1983 ◽  
Vol 1 (2) ◽  
pp. 191-203 ◽  
Author(s):  
J Allen
Keyword(s):  
Spatial Variation ◽  
Philosophy Of Science ◽  
Conceptual Analysis ◽  
Social Research ◽  
Alternative Mode ◽  
Rental Market ◽  
Property Relations ◽  
Mechanistic Approach ◽  
Different Types

Analysis of the role of concepts in urban social research is largely an undeveloped area. Justification of the adoption of particular forms of classification in studies are rarely offered and are often passed over in favour of a discussion of the more tractable areas of empirical research. In this paper the practice of conceptual analysis adopted in one sphere of urban research, landlordism and property relations, is evaluated and criticised for its unreflective mechanistic approach. Invariably, the object (landlordism) is subjected to a form of analysis which treats it as if it were analogous to an onion, from which layers may be peeled off, one after another. It is argued that this mode of analysis does not reveal the economic and social properties that constitute different types of landlordism, which, in turn, may provide the basis for an understanding of the spatial variation in the structure of the market for privately rented housing in Britain. An alternative mode of conceptual analysis, based upon the principles of a realist philosophy of science, is proposed, which has the potential to explain the structural unevenness of the rental market and the roles adopted by different groups of landlords in this market.

Spatial variation of amount effect over peninsular India and Sri Lanka: Role of seasonality

2015 ◽  
Vol 42 (13) ◽  
pp. 5500-5507 ◽  
Author(s):  
P. R. Lekshmy ◽  
M. Midhun ◽  
R. Ramesh
Keyword(s):  
Sri Lanka ◽  
Spatial Variation ◽  
Peninsular India ◽  
Amount Effect

scholarly journals Effects of Invariant NKT Cells on Parasite Infections and Hygiene Hypothesis

2016 ◽  
Vol 2016 ◽  
pp. 1-9 ◽  
Author(s):  
Jun-Qi Yang ◽  
Yonghua Zhou ◽  
Ram Raj Singh
Keyword(s):  
Hygiene Hypothesis ◽  
Lymphoid Cells ◽  
Parasitic Infections ◽  
Inkt Cells ◽  
Invariant Nkt Cells ◽  
Natural Ligands ◽  
Parasite Infections ◽  
Underlying Mechanisms ◽  
Invariant Natural Killer

Invariant natural killer T (iNKT) cells are unique subset of innate-like T cells recognizing glycolipids. iNKT cells can rapidly produce copious amounts of cytokines upon antigen stimulation and exert potent immunomodulatory activities for a wide variety of immune responses and diseases. We have revealed the regulatory effect of iNKT cells on autoimmunity with a serial of publications. On the other hand, the role of iNKT cells in parasitic infections, especially in recently attractive topic “hygiene hypothesis,” has not been clearly defined yet. Bacterial and parasitic cell wall is a cellular structure highly enriched in a variety of glycolipids and lipoproteins, some of which may serve as natural ligands of iNKT cells. In this review, we mainly summarized the recent findings on the roles and underlying mechanisms of iNKT cells in parasite infections and their cross-talk with Th1, Th2, Th17, Treg, and innate lymphoid cells. In most cases, iNKT cells exert regulatory or direct cytotoxic roles to protect hosts against parasite infections. We put particular emphasis as well on the identification of the natural ligands from parasites and the involvement of iNKT cells in the hygiene hypothesis.

scholarly journals Spatial Variation in Demographic Processes and the Potential Role of Hybridization to Future Persistence

2021 ◽  
Author(s):  
Meaghan R Gade ◽  
Qing Zhao ◽  
William E Peterman
Keyword(s):  
Spatial Variation ◽  
Spatial Scales ◽  
High Elevation ◽  
Spatially Explicit ◽  
Fine Scale ◽  
Demographic Rates ◽  
Demographic Traits ◽  
Demographic Processes ◽  
Demographic Responses

Abstract CONTEXTSpatial variation in life history traits plays a crucial role in the structure and dynamics of populations. The demographic responses of local populations to fine-scale habitat heterogeneity have consequences for species at a broader scale and responses vary across spatial scales. Yet, the specific nature of such relationships is unclear across taxa.OBJECTIVESWe evaluated the spatial variation in demographic traits of cryptic terrestrial salamanders across the broad scale environmental gradient of elevation (i.e. temperature) and the fine-scale gradient of stream distance (i.e. moisture).METHODSUsing a 4-years of spatial mark-recapture and count data, we implemented a spatially explicit Integrated Population Model to understand demographic rates across scales. We also investigated how hybridization, which occurs in between lungless salamanders at mid-elevations, may influence demographic rates.RESULTSWe found that high elevation animals grow faster and move more, especially far from streams likely as a result of increased temperatures. Survival was highest but recruitment rates were lowest at low elevations and significantly declined with distance to stream. We also found that hybrid animals at low elevations had higher survival probabilities.CONCLUSIONSOur study reveals nuanced spatial variation in demographic rates that differ in magnitude depending on the scale at which they are assessed. Our results also show animals exhibit demographic compensation across abiotic gradients, underscoring the need for further conservation and management efforts to implement spatially explicit and dynamic strategies to match the demographic variation of species and populations of species separated across space.

scholarly journals The Role of Institutional Environment in International Trade. The Case of Spanish Regions

REGION ◽  
2016 ◽  
Vol 3 (2) ◽  
pp. 125
Author(s):  
Laura Márquez-Ramos
Keyword(s):  
International Trade ◽  
Spatial Variation ◽  
Institutional Environment ◽  
Institutional Quality ◽  
Trade Agreements ◽  
Common Trend ◽  
Spanish Regions ◽  
Heterogeneous Effect

We move beyond the nation-state as the unit of analysis and use subnational spatial variation to study the effect of the institutional environment on international trade. Additionally, we address the heterogeneous effect of trade agreements on different regions within a country. Employing a gravity model approach, we use a region-to-country dataset to estimate the determinants of Spanish regional exports and we apply quantile regressions for panel data. We find that better institutional quality of trade agreements leads to an increase in both the intensive and the extensive margins of trade. The institutional quality of trade agreements exerts a differential effect on regional exports at different locations within a country, although differences across Spanish regions seem to be larger for the intensive margin than for the extensive margin. We do, however, find a common trend: for the relatively more important exporting regions, the institutional quality of TAs is less relevant for trade margins. Therefore, our results posit that subnational spatial variation should be added to the analysis of the determinants of international trade flows.

The passion of place

2003 ◽  
Author(s):  
Doreen Massey ◽  
Nigel Thrirt
Keyword(s):  
Spatial Variation ◽  
Human Geography ◽  
History Of ◽  
Separate Region

Place has long been a key element in geographical thought and writing. Along with ‘region’, it has been a core conceptual focus of what geography, or certainly human geography, has been thought to be about. In some ways, indeed, it is hard to separate region from place or place from region. ‘Places’ as objects of conceptualisation and of research raise some crucial issues that have long been the concern of geographers: the issue of spatial variation, the conceptualisation of space, and the passivity or influence of the spatial realm; the ‘problem’ of specificity and uniqueness, of the significance of these and of how (indeed whether) they can be ‘scientifically’ analysed; issues around the conceptualisation of ‘identity’; and the problems and possibilities of geography's supposed character as a synthesising discipline. This chapter recounts a history of the role of place in British geography.

Stimulus Intensity and Spatiality in Tactile Temporal Numerosity Discrimination

Perception ◽  
1974 ◽  
Vol 3 (3) ◽  
pp. 297-302 ◽  
Author(s):  
E C Lechelt
Keyword(s):  
Spatial Variation ◽  
Signal Intensity ◽  
Presentation Rate ◽  
Middle Finger ◽  
Absolute Judgment ◽  
Numerosity Discrimination ◽  
Multiple Loci ◽  
Stimulus Complex ◽  
Left Middle

The role of signal intensity in tactile temporal numerosity discrimination was investigated for limited conditions of signal number and presentation rate. Trains of 5 to 18 mechanical ‘taps’ were presented at rates of 6, 8, 10, 12, or 15 s−1 to the ball of the left middle finger at either 75 or 125 V (15 or 20 dB SL, respectively). Trains of signals of greater intensity were counted reliably more accurately. Results from this spatially static arrangement are compared to those obtained under conditions of spatial variation where signals of identical intensity were delivered to multiple loci instead of to a single locus. It is concluded that the absolute judgment of the number of tactile signals in a train is a very labile process and highly dependent upon, and specific to, the physical characteristics—temporal, spatial, and intensive—of the stimulus complex.

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