103 research outputs found
Sacred fig trees promote frugivore visitation and tree seedling abundance in South India
While sacred groves (forest fragments protected for
religious reasons) are widely acknowledged to have a
beneficial effect on biodiversity conservation, the ecological benefits of individual sacred trees remain unknown. Fig trees are present as sacred trees in humandominated landscapes across South Asia and are considered keystone species for wildlife in tropical forests. If frugivores continue to visit fig trees in disturbed landscapes, they may deposit seeds of other tree species beneath fig canopies, ultimately facilitating forest regeneration. We studied whether sacred fig trees in Tamil Nadu, India can facilitate seed dispersal in human-dominated landscapes. We quantified abundance of sacred fig trees at the study site, assessed
whether seed-dispersing frugivore visitation to fig
trees is affected by human disturbance, and compared
tree seedling density beneath fig trees and open areas.
We found that some species of frugivorous birds and
bats will visit large fig trees in conditions of high
human disturbance and that tree seedling density is
significantly higher under sacred trees compared to
open areas. By promoting frugivore activity, sacred
fig trees may have a beneficial effect on biodiversity
conservation in human-dominated landscapes
Scaling Up Sagebrush Chemistry with Near-Infrared Spectroscopy and UAS-Acquired Hyperspectral Imagery
Sagebrush ecosystems (Artemisia spp.) face many threats including large wildfires and conversion to invasive annuals, and thus are the focus of intense restoration efforts across the western United States. Specific attention has been given to restoration of sagebrush systems for threatened herbivores, such as Greater Sage-Grouse (Centrocercus urophasianus) and pygmy rabbits (Brachylagus idahoensis), reliant on sagebrush as forage. Despite this, plant chemistry (e.g., crude protein, monoterpenes and phenolics) is rarely considered during reseeding efforts or when deciding which areas to conserve. Near-infrared spectroscopy (NIRS) has proven effective in predicting plant chemistry under laboratory conditions in a variety of ecosystems, including the sagebrush steppe. Our objectives were to demonstrate the scalability of these models from the laboratory to the field, and in the air with a hyperspectral sensor on an unoccupied aerial system (UAS). Sagebrush leaf samples were collected at a study site in eastern Idaho, USA. Plants were scanned with an ASD FieldSpec 4 spectroradiometer in the field and laboratory, and a subset of the same plants were imaged with a SteadiDrone Hexacopter UAS equipped with a Rikola hyperspectral sensor (HSI). All three sensors generated spectral patterns that were distinct among species and morphotypes of sagebrush at specific wavelengths. Lab-based NIRS was accurate for predicting crude protein and total monoterpenes (R2 = 0.7–0.8), but the same NIRS sensor in the field was unable to predict either crude protein or total monoterpenes (R2 \u3c 0.1). The hyperspectral sensor on the UAS was unable to predict most chemicals (R2 \u3c 0.2), likely due to a combination of too few bands in the Rikola HSI camera (16 bands), the range of wavelengths (500–900 nm), and small sample size of overlapping plants (n = 28–60). These results show both the potential for scaling NIRS from the lab to the field and the challenges in predicting complex plant chemistry with hyperspectral UAS. We conclude with recommendations for next steps in applying UAS to sagebrush ecosystems with a variety of new sensors
Jump-Starting the Socialization Experience: The Longitudinal Role of Day 1 Newcomer Resources on Adjustment
This is the author accepted manuscript. the final version is available from SAGE Publications via the DOI in this recordWe examine the newcomer adjustment patterns of 985 new hires at a Fortune 500 technology organization across their first year on the job. Data were collected from newcomers, their managers, and company records from organizational entry (employee’s first day) to the end of the first year of employment. We examined, first, whether newcomer resources (material, personal, social, and status resources) related to early newcomer adjustment levels (role clarity, task mastery, and acceptance) and rates of adjustment and, second, how newcomer resources and the rate of adjustment related to manager ratings of newcomer adjustment at 9 and 12 months post-entry. The average of every adjustment variable was higher at the latest data collection point, indicating that time was on newcomers’ side and was related, overall, to higher adjustment levels. Finally, we explored which resources related to the three newcomer adjustment indicators and the shapes adjustment trajectories took depending on resources at organizational entry. Results indicated that personal resources (proactive personality, optimism, and organizational knowledge) were related to early adjustment. Regarding material resources, having a work station ready the first day on the job was related to adjustment. For social resources, meeting one’s manager the first day on the job was related to early social acceptance. For status resources, greater newcomer job level was unexpectedly not related to early adjustment. We found partial support for the direct relationships between early adjustment levels or adjustment rates and manager ratings of adjustment at 9 months but limited support for manager ratings of adjustment at 12 months
Increased Expression of Simple Ganglioside Species GM2 and GM3 Detected by MALDI Imaging Mass Spectrometry in a Combined Rat Model of A beta Toxicity and Stroke
The aging brain is often characterized by the presence of multiple comorbidities resulting in synergistic damaging effects in the brain as demonstrated through the interaction of Alzheimer\u27s disease (AD) and stroke. Gangliosides, a family of membrane lipids enriched in the central nervous system, may have a mechanistic role in mediating the brain\u27s response to injury as their expression is altered in a number of disease and injury states. Matrix-Assisted Laser Desorption Ionization (MALDI) Imaging Mass Spectrometry (IMS) was used to study the expression of A-series ganglioside species GD1a, GM1, GM2, and GM3 to determine alteration of their expression profiles in the presence of beta-amyloid (A beta) toxicity in addition to ischemic injury. To model a stroke, rats received a unilateral striatal injection of endothelin-1 (ET-1) (stroke alone group). To model A beta toxicity, rats received intracerebralventricular (icv) injections of the toxic 25-35 fragment of the A beta peptide (A beta alone group). To model the combination of A beta toxicity with stroke, rats received both the unilateral ET-1 injection and the bilateral icv injections of A beta(25-35) (combined A beta/ET-1 group). By 3 d, a significant increase in the simple ganglioside species GM2 was observed in the ischemic brain region of rats who received a stroke (ET-1), with or without A beta. By 21 d, GM2 levels only remained elevated in the combined A beta/ET-1 group. GM3 levels however demonstrated a different pattern of expression. By 3 d GM3 was elevated in the ischemic brain region only in the combined A beta/ET-1 group. By 21 d, GM3 was elevated in the ischemic brain region in both stroke alone and A beta/ET-1 groups. Overall, results indicate that the accumulation of simple ganglioside species GM2 and GM3 may be indicative of a mechanism of interaction between AD and stroke
Pulsation modes in rapidly rotating stellar models based on the Self-Consistent Field method
Context: New observational means such as the space missions CoRoT and Kepler
and ground-based networks are and will be collecting stellar pulsation data
with unprecedented accuracy. A significant fraction of the stars in which
pulsations are observed are rotating rapidly.
Aims: Our aim is to characterise pulsation modes in rapidly rotating stellar
models so as to be able to interpret asteroseismic data from such stars.
Methods: The pulsation code developed in Ligni\`eres et al. (2006) and Reese
et al. (2006) is applied to stellar models based on the self-consistent field
(SCF) method (Jackson et al. 2004, 2005, MacGregor et al. 2007).
Results: Pulsation modes in SCF models follow a similar behaviour to those in
uniformly rotating polytropic models, provided that the rotation profile is not
too differential. Pulsation modes fall into different categories, the three
main ones being island, chaotic, and whispering gallery modes, which are
rotating counterparts to modes with low, medium, and high l-|m| values,
respectively. The frequencies of the island modes follow an asymptotic pattern
quite similar to what was found for polytropic models. Extending this
asymptotic formula to higher azimuthal orders reveals more subtle behaviour as
a function of m and provides a first estimate of the average advection of
pulsation modes by rotation. Further calculations based on a variational
principle confirm this estimate and provide rotation kernels that could be used
in inversion methods. When the rotation profile becomes highly differential, it
becomes more and more difficult to find island and whispering gallery modes at
low azimuthal orders. At high azimuthal orders, whispering gallery modes, and
in some cases island modes, reappear.Comment: 16 pages, 11 figures, accepted for publication in A&
Relational consequences of compulsive Internet use: A longitudinal study among newlyweds
This article examines how compulsive Internet use and marital well-being are related to each other. We suggest that they are negatively related and explore whether compulsive Internet use predicts marital well-being or vice versa. The relation between compulsive Internet use and marital well-being is tested in a two-wave prospective study among 190 newlywed couples. The results suggest that (a) compulsive Internet use predicts marital well-being, and not vice versa, (b) that this is a within- rather than a cross-partner effect, and (c) that the frequency of Internet use may be positively related to marital well-being. The results are discussed in terms of the mechanisms that underlie the link between compulsive Internet use and relationship quality
Peer Acceptance Protects Global Self-esteem from Negative Effects of Low Closeness to Parents During Adolescence and Early Adulthood
Is the keystone role of figs maintained across a gradient of increasing human disturbance?
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