1,335 research outputs found
Interactions Between an Apex Predator and Mesopredators Across a Landscape with Human Interference
Human activities have populated the planet with domestic animals like livestockwhile also eliminating wild species that could conflict with them. We investigatedfactors affecting predator occurrence in semiarid landscapes of centralArgentina and tested for evidence of mesopredator release at large scales. Ourstudy region has a few, small protected areas interspersed within a mosaic of livestockranches and game hunting grounds. We hypothesized that mesopredatorswould avoid spatial and temporal overlap with the apex predator, the puma, butthat human activities (i.e., cattle raising and trophy hunting) would dampen top-downeffects and mediate habitat use of smaller carnivores.Fil: Zanón Martínez, Juan Ignacio. Consejo Nacional de Investigaciones Científicas y Técnicas. Instituto de Ciencias de la Tierra y Ambientales de La Pampa. Universidad Nacional de La Pampa. Facultad de Ciencias Exactas y Naturales. Instituto de Ciencias de la Tierra y Ambientales de La Pampa; ArgentinaFil: Seoane, Javier. Universidad Autónoma de Madrid; EspañaFil: Kelly, Marcella J.. Virginia Tech University; Estados UnidosFil: Sarasola, José Hernán. Consejo Nacional de Investigaciones Científicas y Técnicas. Instituto de Ciencias de la Tierra y Ambientales de La Pampa. Universidad Nacional de La Pampa. Facultad de Ciencias Exactas y Naturales. Instituto de Ciencias de la Tierra y Ambientales de La Pampa; ArgentinaFil: Travaini, Alejandro. Universidad Nacional de la Patagonia Austral. Unidad Académica Caleta Olivia. Centro de Investigaciones Puerto Deseado; Argentina. Consejo Nacional de Investigaciones Científicas y Técnicas; Argentin
Assessing carnivore spatial co‐occurrence and temporal overlap in the face of human interference in a semi‐arid forest
Apex predators drive top-down effects in ecosystems and the loss of such species can trigger mesopredator release. This ecological process has been well documented in human-modified small areas, but for management and conservation of ecological communities, it is important to know which human factors affect apex predator occurrence and which mediate mesopredators release at large scales. We hypothesized that mesopredators would avoid spatial and temporal overlap with the apex predator, the puma; but that human perturbations (i.e. cattle raising and trophy hunting) would dampen top-down effects and mediate habitat use. We installed 16 camera traps in each of 45, 10x10-km grid cells in the Caldén forest region of central Argentina resulting in 706 total stations covering 61,611km2. We used single-season occupancy and two-species co-occurrence models and calculated the species interaction factor (SIF) to explore the contributions of habitat, biotic, and anthropic variables in explaining co-occurrence between carnivore pairs. We also used kernel density estimation techniques to analyze temporal overlap in activity patterns of the carnivore guild. We found that puma habitat use increased with abundance of large prey and with proximity to protected areas. Geoffroy´s cats and skunks spatially avoided pumas and this effect was strong and mediated by distance to protected areas and game reserves, but pumas did not influence pampas fox and pampas cat space use. At medium and low levels of puma occupancy, we found evidence of spatial avoidance between 3 pairs of mesocarnivores. All predators were mostly nocturnal and crepuscular across seasons and mesopredators showed little consistent evidence of changing activity patterns with varying levels of puma occupancy or human interference. We found potential for mesopredator release at large scale, especially on the spatial niche axis. Our results suggest that a combination of interacting factors, in conjunction with habitat features and intervening human activities, may make mesopredator release unlikely or difficult to discern at broad scales. Overall, we believe that promoting the creation of new protected areas linked by small forest patches would likely lead to increased predator and prey abundances, as well as the interactions among carnivores inside and outside of protected areas.Fil: Zanón Martínez, Juan Ignacio. Consejo Nacional de Investigaciones Científicas y Técnicas. Instituto de Ciencias de la Tierra y Ambientales de La Pampa. Universidad Nacional de La Pampa. Facultad de Ciencias Exactas y Naturales. Instituto de Ciencias de la Tierra y Ambientales de La Pampa; Argentina. Universidad Nacional de La Pampa. Facultad de Ciencia Exactas y Naturales. Departamento de Recursos Naturales. Centro para el Estudio y Conservación de Aves Rapaces; ArgentinaFil: Seoane, Javier. Universidad Autónoma de Madrid; EspañaFil: Kelly, Marcella J.. Virginia Tech University; Estados UnidosFil: Sarasola, José Hernán. Consejo Nacional de Investigaciones Científicas y Técnicas. Instituto de Ciencias de la Tierra y Ambientales de La Pampa. Universidad Nacional de La Pampa. Facultad de Ciencias Exactas y Naturales. Instituto de Ciencias de la Tierra y Ambientales de La Pampa; Argentina. Universidad Nacional de La Pampa. Facultad de Ciencia Exactas y Naturales. Departamento de Recursos Naturales. Centro para el Estudio y Conservación de Aves Rapaces; ArgentinaFil: Travaini, Alejandro. Universidad Nacional de la Patagonia Austral. Unidad Académica Caleta Olivia. Centro de Investigaciones Puerto Deseado; Argentina. Consejo Nacional de Investigaciones Científicas y Técnicas; Argentin
Exploring and interpreting spatiotemporal interactions between native and invasive carnivores across a gradient of rainforest degradation
Studies of elusive carnivores often rely on passive sampling when investigating either spatial or temporal interactions. However, inference on behavioral mechanisms are usually lacking. We present an analysis that combines previously published spatial co-occurrence estimates and temporal kernel density estimates to explore spatiotemporal interspecific interactions. We do so by deriving a spatiotemporal value (STV) that is a relative measure of potential interaction in both niche dimensions, across a gradient of degradation, for rainforest carnivore pairs in Madagascar. We also use a conceptual framework to provide insight into the potential behavioral mechanisms of habitat selection. Of the six native and three invasive carnivores, we estimate the spatiotemporal interactions for twelve pairings, which range from no spatial/temporal relationship (n = 5) to spatiotemporal aggregation or segregation (n = 7). We visualized these spatiotemporal interactions along a fragmentation gradient and demonstrate that these interactions are not static, as STV overlap increases with increasing anthropogenic disturbance. Of the three invasive carnivores (free-ranging dogs Canis familiaris, cats Felis species, and small Indian civets Viverricula indica) the latter had the highest number of spatial occurrence (n = 4) and spatiotemporal overlap (n = 4) relationships with native carnivores. Our results highlight the potential for increasing direct and indirect interactions between native and invasive species as forest degradation and invasive predators increase. Our approach allows us to better understand adaptive behaviors, plasticity in temporal activity, community assemblage, and to develop targeted conservation strategies to manage ecological communities in rapidly changing ecosystems
Observational limits on type 1 active galactic nucleus rate in COSMOS
We present black hole masses and accretion rates for 182 Type 1 active galactic nuclei (AGNs) in COSMOS.
We estimate masses using the scaling relations for the broad H β, Mg ii, and C iv emission lines in the
redshift ranges 0.16 < z < 0.88, 1 < z < 2.4, and 2.7 < z < 4.9. We estimate the accretion rate using an
Eddington ratio LI/L_(Edd) estimated from optical and X-ray data.We find that very few Type 1 AGNs accrete below
LI/L_(Edd) ∼ 0.01, despite simulations of synthetic spectra which show that the survey is sensitive to such Type
1 AGNs. At lower accretion rates the broad-line region may become obscured, diluted, or nonexistent. We find
evidence that Type 1 AGNs at higher accretion rates have higher optical luminosities, as more of their emission
comes from the cool (optical) accretion disk with respect to shorter wavelengths. We measure a larger range
in accretion rate than previous works, suggesting that COSMOS is more efficient at finding low accretion rate
Type 1 AGNs. However, the measured range in accretion rate is still comparable to the intrinsic scatter from the
scaling relations, suggesting that Type 1 AGNs accrete at a narrow range of Eddington ratio, with LI/L_(Edd) ∼ 0.1
Observational Limits on Type 1 AGN Accretion Rate in COSMOS
We present black hole masses and accretion rates for 182 Type 1 AGN in
COSMOS. We estimate masses using the scaling relations for the broad Hb, MgII,
and CIV emission lines in the redshift ranges 0.16<z<0.88, 1<z<2.4, and
2.7<z<4.9. We estimate the accretion rate using an Eddington ratio L_I/L_Edd
estimated from optical and X-ray data. We find that very few Type 1 AGN accrete
below L_I/L_Edd ~ 0.01, despite simulations of synthetic spectra which show
that the survey is sensitive to such Type 1 AGN. At lower accretion rates the
BLR may become obscured, diluted or nonexistent. We find evidence that Type 1
AGN at higher accretion rates have higher optical luminosities, as more of
their emission comes from the cool (optical) accretion disk with respect to
shorter wavelengths. We measure a larger range in accretion rate than previous
works, suggesting that COSMOS is more efficient at finding low accretion rate
Type 1 AGN. However the measured range in accretion rate is still comparable to
the intrinsic scatter from the scaling relations, suggesting that Type 1 AGN
accrete at a narrow range of Eddington ratio, with L_I/L_Edd ~ 0.1.Comment: Accepted for pulication in ApJ. 7 pages, 5 figures, table 1 available
on reques
Threat of Hantavirus Pulmonary Syndrome to Field Biologists Working with Small Mammals
Field biologists should use personal protective equipment appropriate for their activities
The Nature of Optically Dull Active Galactic Nuclei in COSMOS
We present infrared, optical, and X-ray data of 48 X-ray bright, optically
dull AGNs in the COSMOS field. These objects exhibit the X-ray luminosity of an
active galactic nucleus (AGN) but lack broad and narrow emission lines in their
optical spectrum. We show that despite the lack of optical emission lines, most
of these optically dull AGNs are not well-described by a typical passive red
galaxy spectrum: instead they exhibit weak but significant blue emission like
an unobscured AGN. Photometric observations over several years additionally
show significant variability in the blue emission of four optically dull AGNs.
The nature of the blue and infrared emission suggest that the optically
inactive appearance of these AGNs cannot be caused by obscuration intrinsic to
the AGNs. Instead, up to ~70% of optically dull AGNs are diluted by their
hosts, with bright or simply edge-on hosts lying preferentially within the
spectroscopic aperture. The remaining ~30% of optically dull AGNs have
anomalously high f_x/f_o ratios and are intrinsically weak, not obscured, in
the optical. These optically dull AGNs are best described as a weakly accreting
AGN with a truncated accretion disk from a radiatively inefficient accretion
flow.Comment: 12 pages, 10 figures. Accepted for publication in the Ap
The COSMOS AGN Spectroscopic Survey I: XMM Counterparts
We present optical spectroscopy for an X-ray and optical flux-limited sample
of 677 XMM-Newton selected targets covering the 2 deg^2 COSMOS field, with a
yield of 485 high-confidence redshifts. The majority of the spectra were
obtained over three seasons (2005-2007) with the IMACS instrument on the
Magellan (Baade) telescope. We also include in the sample previously published
Sloan Digital Sky Survey spectra and supplemental observations with
MMT/Hectospec. We detail the observations and classification analyses. The
survey is 90% complete to flux limits of f_{0.5-10 keV}>8 x 10^-16 erg cm^-2
s^-1 and i_AB+<22, where over 90% of targets have high-confidence redshifts.
Making simple corrections for incompleteness due to redshift and spectral type
allows for a description of the complete population to $i_AB+<23. The corrected
sample includes 57% broad emission line (Type 1, unobscured) AGN at
0.13<z<4.26, 25% narrow emission line (Type 2, obscured) AGN at 0.07<z<1.29,
and 18% absorption line (host-dominated, obscured) AGN at 0<z<1.22 (excluding
the stars that made up 4% of the X-ray targets). We show that the survey's
limits in X-ray and optical flux include nearly all X-ray AGN (defined by
L_{0.5-10 keV}>3 x 10^42 erg s^-1) to z<1, of both optically obscured and
unobscured types. We find statistically significant evidence that the obscured
to unobscured AGN ratio at z<1 increases with redshift and decreases with
luminosity.Comment: Accepted for publication in the ApJ. 31 pages, 17 figures. Table 2 is
available on reques
Development of a psychiatric disorder linked to cerebellar lesions
Cerebellar dysfunction plays a critical role in neurodevelopmental disorders with long-term behavioral and neuropsychiatric symptoms. A 43-year-old woman with a cerebellum arteriovenous malformation and history of behavioral dysregulation since childhood is described. After the rupture of the cerebellar malformation in adulthood, her behavior morphed into specific psychiatric symptoms and cognitive deficits occurred. The neuropsychological assessment evidenced impaired performance in attention, visuospatial, memory, and language domains. Moreover, psychiatric assessment indicated a borderline personality disorder. Brain MRI examination detected macroscopic abnormalities in the cerebellar posterior lobules VI, VIIa (Crus I), and IX, and in the posterior area of the vermis, regions usually involved in cognitive and emotional processing. The described patient suffered from cognitive and behavioral symptoms that are part of the cerebellar cognitive affective syndrome. This case supports the hypothesis of a cerebellar role in personality disorders emphasizing the importance of also examining the cerebellum in the presence of behavioral disturbances in children and adults
Cross-sectional interactions between quality of the physical and social environment and self-reported physical activity in adults living in income-deprived communities
Background: Understanding the environmental determinants of physical activity in populations at high risk of inactivity could contribute to the development of effective interventions. Socioecological models of activity propose that environmental factors have independent and interactive effects of physical activity but there is a lack of research into interactive effects.
Objectives:
This study aimed to explore independent and interactive effects of social and physical environmental factors on self-reported physical activity in income-deprived communities.
Methods:
Participants were 5,923 adults in Glasgow, United Kingdom. Features of the social environment were self-reported. Quality of the physical environment was objectively-measured. Neighbourhood walking and participation in moderate physical activity [MPA] on ≥5 days/week was self-reported. Multilevel multivariate logistic regression models tested independent and interactive effects of environmental factors on activity.
Results:
‘Social support’ (walking: OR:1.22,95%CI=1.06-1.41,p<0.01; MPA: OR:0.79,95%CI=0.67-0.94,p<0.01), ‘social interaction’ (walking: OR:1.25,95%CI=1.10-1.42,p<0.01; MPA: OR:6.16,95%CI=5.14-7.37,p<0.001) and ‘cohesion and safety’ (walking: OR:1.78,95%CI=1.56-2.03,p<0.001; MPA: OR:1.93,95%CI=1.65-2.27,p<0.001), but not ‘trust and empowerment’, had independent effects on physical activity. ‘Aesthetics of built form’ (OR:1.47,95%CI=1.22-1.77,p<0.001) and ‘aesthetics and maintenance of open space’ (OR:1.32, 95%CI=1.13-1.54,p<0.01) were related to walking. ‘Physical disorder’ (OR:1.63,95%CI=1.31-2.03,p<0.001) had an independent effect on MPA. Interactive effects of social and physical factors on walking and MPA were revealed.
Conclusions:
Findings suggest that intervening to create activity-supportive environments in deprived communities may be most effective when simultaneously targeting the social and physical neighbourhood environment
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