72 research outputs found

    Cascading effects of a highly specialized beech-aphid–fungus interaction on forest regeneration

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    Specialist herbivores are thought to often enhance or maintain plant diversity within ecosystems, because they prevent their host species from becoming competitively dominant. In contrast, specialist herbivores are not generally expected to have negative impacts on non-hosts. However, we describe a cascade of indirect interactions whereby a specialist sooty mold (Scorias spongiosa) colonizes the honeydew from a specialist beech aphid (Grylloprociphilus imbricator), ultimately decreasing the survival of seedlings beneath American beech trees (Fagus grandifolia). A common garden experiment indicated that this mortality resulted from moldy honeydew impairing leaf function rather than from chemical or microbial changes to the soil. In addition, aphids consistently and repeatedly colonized the same large beech trees, suggesting that seedling-depauperate islands may form beneath these trees. Thus this highly specialized three-way beech-aphid–fungus interaction has the potential to negatively impact local forest regeneration via a cascade of indirect effects

    SHARED TEAM EXPERIENCES AND TEAM EFFECTIVENESS: UNPACKING THE CONTINGENT EFFECTS OF ENTRAINED RHYTHMS AND TASK CHARACTERISTICS

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    This study explores the conditions under which shared team task-specific (STTS) experiences in crew-based arrangements may negatively influence team effectiveness.We suggest that the entrained rhythms featured in social entrainment theory act as a dual-edged sword with the potential to generate complacency detriments in addition to the commonly cited synchronization benefits. We argue that the manifestation and influence of the countervailing forces (i.e., synchronization and complacency) on the STTS experience—team effectiveness relationship will depend on salient task characteristics (i.e., frequency and difficulty). More specifically, frequently performed tasks create conditions for complacency tomanifest (generating an inverted-U shaped relationship between STTS experience—team efficiency), whereas infrequently performed tasks do not (generating a positive, linear relationship). We further this distinction by layering on task difficulty that, we posit, acts to amplify the respective negative and positive consequences. Analyses of archival data from 8,236 surgeries performed over one year at a large hospital located in the southwestern region of the United States were consistent with our hypotheses and 30 semi-structured interviews with operating room personnel added richness and precision to our theory. Ancillary analyses on patient post-surgery recovery rate yielded additional insights. Implications and future directions are discussed

    SHARED TEAM EXPERIENCES AND TEAM EFFECTIVENESS: UNPACKING THE CONTINGENT EFFECTS OF ENTRAINED RHYTHMS AND TASK CHARACTERISTICS

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    This study explores the conditions under which shared team task-specific (STTS) experiences in crew-based arrangements may negatively influence team effectiveness.We suggest that the entrained rhythms featured in social entrainment theory act as a dual-edged sword with the potential to generate complacency detriments in addition to the commonly cited synchronization benefits. We argue that the manifestation and influence of the countervailing forces (i.e., synchronization and complacency) on the STTS experience—team effectiveness relationship will depend on salient task characteristics (i.e., frequency and difficulty). More specifically, frequently performed tasks create conditions for complacency tomanifest (generating an inverted-U shaped relationship between STTS experience—team efficiency), whereas infrequently performed tasks do not (generating a positive, linear relationship). We further this distinction by layering on task difficulty that, we posit, acts to amplify the respective negative and positive consequences. Analyses of archival data from 8,236 surgeries performed over one year at a large hospital located in the southwestern region of the United States were consistent with our hypotheses and 30 semi-structured interviews with operating room personnel added richness and precision to our theory. Ancillary analyses on patient post-surgery recovery rate yielded additional insights. Implications and future directions are discussed

    The Lantern Vol. 64, No. 2, Spring 1997

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    • Year\u27s End, with Resolutions • Addicted • Muerte, Carlos • Motions • At the Wyeth Gallery • Between Contexts • I\u27m Allowed (and More Nonsense) • Wall and Piece • Timekeeper\u27s Workspace • The Process • Second Sex: A Portrait of the Artist as a Woman • On the Side of the Road • Joe • To Matthew Arnold • A Deep Sleep on Hydrocodone • Madness of a Night • Return • The Sudden Grave • A Farce • Twists of Fur • Ambiguity • The Odor of Continuums • My Father\u27s Daughter • The Meaning of Life • I Aim to Tell • Nobody\u27s Fanhttps://digitalcommons.ursinus.edu/lantern/1150/thumbnail.jp

    The Lantern Vol. 63, No. 2, Spring 1996

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    • Poet, Lead Me On • St. Patrick\u27s Day • The Last Three Days • The Impressionable • Roundabout • The Bench • Carnivorous • Kyrie • Second Glance • Porch • Cruel Design • A Mime • Flaxen Crown • My Embryonic Ocean of Love • Stone Matrix • Voices from the Past • Skipping the Bullfight: Toreadors and Gaudi • Another Part of My Lacolonialism • Translucent Pane • Linguistics • Treehouse • A Disagreeable Music Piece • Vigil • A Brief History of American Poetry in Englishhttps://digitalcommons.ursinus.edu/lantern/1148/thumbnail.jp

    BOXIT—A Randomised Phase III Placebo-controlled Trial Evaluating the Addition of Celecoxib to Standard Treatment of Transitional Cell Carcinoma of the Bladder (CRUK/07/004)

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    BACKGROUND:Non-muscle-invasive bladder cancer (NMIBC) has a significant risk of recurrence despite adjuvant intravesical therapy. OBJECTIVE:To determine whether celecoxib, a cyclo-oxygenase 2 inhibitor, reduces the risk of recurrence in NMIBC patients receiving standard treatment. DESIGN, SETTING, AND PARTICIPANTS:BOXIT (CRUK/07/004, ISRCTN84681538) is a double-blinded, phase III, randomised controlled trial. Patients aged ≥18 yr with intermediate- or high-risk NMIBC were accrued across 51 UK centres between 1 November 2007 and 23 July 2012. INTERVENTION:Patients were randomised (1:1) to celecoxib 200mg twice daily or placebo for 2 yr. Patients with intermediate-risk NMIBC were recommended to receive six weekly mitomycin C instillations; high-risk NMIBC cases received six weekly bacillus Calmette-Guérin and maintenance therapy. OUTCOME MEASUREMENTS AND STATISTICAL ANALYSIS:The primary endpoint was time to disease recurrence. Analysis was by intention to treat. RESULTS AND LIMITATIONS:A total of 472 patients were randomised (236:236). With median follow-up of 44 mo (interquartile range: 36-57), 3-yr recurrence-free rate (95% confidence interval) was as follows: celecoxib 68% (61-74%) versus placebo 64% (57-70%; hazard ratio [HR] 0.82 [0.60-1.12], p=0.2). There was no difference in high-risk (HR 0.77 [0.52-1.15], p=0.2) or intermediate-risk (HR 0.90 [0.55-1.48], p=0.7) NMIBC. Subgroup analysis suggested that time to recurrence was longer in pT1 NMIBC patients treated with celecoxib compared with those receiving placebo (HR 0.53 [0.30-0.94], interaction test p=0.04). The 3-yr progression rates in high-risk patients were low: 10% (6.5-17%) and 9.7% (6.0-15%) in celecoxib and placebo arms, respectively. Incidence of serious cardiovascular events was higher in celecoxib (5.2%) than in placebo (1.7%) group (difference +3.4% [-0.3% to 7.2%], p=0.07). CONCLUSIONS:BOXIT did not show that celecoxib reduces the risk of recurrence in intermediate- or high-risk NMIBC, although celecoxib was associated with delayed time to recurrence in pT1 NMIBC patients. The increased risk of cardiovascular events does not support the use of celecoxib. PATIENT SUMMARY:Celecoxib was not shown to reduce the risk of recurrence in intermediate- or high-risk non-muscle-invasive bladder cancer (NMIBC), although celecoxib was associated with delayed time to recurrence in pT1 NMIBC patients. The increased risk of cardiovascular events does not support the use of celecoxib

    Signalling and the Evolution of Cooperative Foraging in Dynamic Environments

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    Understanding cooperation in animal social groups remains a significant challenge for evolutionary theory. Observed behaviours that benefit others but incur some cost appear incompatible with classical notions of natural selection; however, these behaviours may be explained by concepts such as inclusive fitness, reciprocity, intra-specific mutualism or manipulation. In this work, we examine a seemingly altruistic behaviour, the active recruitment of conspecifics to a food resource through signalling. Here collective, cooperative behaviour may provide highly nonlinear benefits to individuals, since group functionality has the potential to be far greater than the sum of the component parts, for example by enabling the effective tracking of a dynamic resource. We show that due to this effect, signalling to others is an evolutionarily stable strategy under certain environmental conditions, even when there is a cost associated to this behaviour. While exploitation is possible, in the limiting case of a sparse, ephemeral but locally abundant nutrient source, a given environmental profile will support a fixed number of signalling individuals. Through a quantitative analysis, this effective carrying capacity for cooperation is related to the characteristic length and time scales of the resource field

    The effects of essential oil from Lippia origanoides and herbal betaine on performance, intestinal integrity, bone mineralization and meat quality in broiler chickens subjected to cyclic heat stress

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    Essential oils (EO) affect performance, intestinal integrity, bone mineralization, and meat quality in broiler chickens subjected to cyclic heat stress (HS). Day-of-hatch Cobb 500 male broiler chicks (n = 475) were randomly divided into four groups. Group 1: No heat stress (Thermoneutral) + control diets with no antibiotics; Group 2: heat stress control + control diets; Group 3: heat stress + control diets supplemented with thymol chemotype (45 ppm) and herbal betaine (150 ppm) formulation EO1; Group 4: heat stress + control diets supplemented with phellandrene (45 ppm) and herbal betaine (150 ppm) formulation EO2. From day 10–42, the heat stress groups were exposed to cyclic HS at 35°C for 12 h (8:00–20:00). BW, BWG, FI, and FCRc were measured at d 0, 10, 28, and 42. Chickens were orally gavaged with FITC-d on days 10 (before heat stress) and 42. Morphometric analysis of duodenum and ileum samples and bone mineralization of tibias were done. Meat quality was assessed on day 43 with ten chickens per pen per treatment. Heat stress reduced BW by day 28 (p < 0.05) compared to thermoneutral chickens. At the end of the trial, chickens that received both formulations of EO1 and EO2 had significantly higher BW than HS control chickens. A similar trend was observed for BWG. FCRc was impaired by EO2 supplementation. There was a significant increase in total mortality in EO2 compared with EO1 EO1 chickens had lower FITC-d concentrations at day 42 than the HS control. In addition, EO1 treatment is not statistically different if compared to EO2 and thermoneutral. Control HS broilers had significantly lower tibia breaking strength and total ash at day 42 than heat-stressed chickens supplemented with EO1 and EO2. Heat stress affected intestinal morphology more than thermoneutral chickens. EO1 and EO2 improved intestinal morphology in heat-stressed chickens. Woody breast and white striping were more common in thermoneutral chickens than heat stress chickens. In conclusion, the EO-containing diet could improve broiler chicken growth during cyclic heat stress, becoming increasingly relevant in antibiotic-free production in harsh climates
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