3,550 research outputs found

    Effects of Hurricane Disturbance on Stream Water Concentrations and Fluxes in Eight Tropical Forest Watersheds of the Luquillo Experimental Forest, Puerto Rico

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    Stream water chemistry responds substantially to watershed disturbances, but hurricane effects have not been extensively investigated in tropical regions. This study presents a long-term (2.5-11 y) weekly record of stream water chemistry on eight forested watersheds (catchment basins) in the Luquillo Mountains of Puerto Rico. This includes a period before and at least 2 y after the disturbance caused by the 1989 Hurricane Hugo. Nitrate, potassium and ammonium concentrations increased after the hurricane and remained elevated for up to 2 y. Sulphate, chloride, sodium, magnesium and calcium showed smaller relative significant changes. Average stream water exports of potassium, nitrate and ammonium increased by 13.1, 3.6 and 0.54 kg ha -1 y -1 in the first post-hurricane year across all watersheds. These represent increases of 119, 182 and 102 of record. The increased stream outputs of potassium and nitrogen in the first 2 y post-hurricane are equivalent to 3of the hurricane-derived plant litter. Effects of hurricanes on tropical stream water potassium and nitrogen can be greater than those caused by canopy gaps or limited forest cutting, but less than those following large-scale deforestation or fire

    Dissolved organic carbon uptake in streams: A review and assessment of reach‐scale measurements

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    Quantifying the role that freshwater ecosystems play in the global carbon cycle requires accurate measurement and scaling of dissolved organic carbon (DOC) removal in river networks. We reviewed reach‐scale measurements of DOC uptake from experimental additions of simple organic compounds or leachates to inform development of aquatic DOC models that operate at the river network, regional, or continental scale. Median DOC uptake velocity (vf) across all measurements was 2.28 mm min−1. Measurements using simple compound additions resulted in faster vf (2.94 mm min−1) than additions of leachates (1.11 mm min−1). We also reviewed published data of DOC bioavailability for ambient stream water and leaf leachate DOC from laboratory experiments. We used these data to calculate and apply a correction factor to leaf leachate uptake velocity to estimate ambient stream water DOC uptake rates at the reach scale. Using this approach, we estimated a median ambient stream DOC vf of 0.26 mm min−1. Applying these DOC vf values (0.26, 1.11, 2.28, and 2.94 mm min−1) in a river network inverse model in seven watersheds revealed that our estimated ambient DOC vf value is plausible at the network scale and 27 to 45% of DOC input was removed. Applying the median measured simple compound or leachate vf in whole river networks would require unjustifiably high terrestrial DOC inputs to match observed DOC concentrations at the basin mouth. To improve the understanding and importance of DOC uptake in fluvial systems, we recommend using a multiscale approach coupling laboratory assays, with reach‐scale measurements, and modeling

    Potential of Deshi Cattle of India for Dairy Production

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    There were 1,405 lactation records of 336 cows at the Central Livestock Research- cum-Breeding Station, Haringhata, India from 1958 to 1968 used to estimate the potential dairy merit of Deshi cattle. This breed is native to northeast India and one of the smallest breeds in India (mature females 200 kg and males 250 kg). Averages and standard deviations for milk yield (exclusive of that suckled), age of first calving, calving interval, lactation length, days open, and days dry were 412 ± 178 kg, 44.5 ± 6.8 months, 419 ± 90 days, 264 ± 81 days, 135 ± 86 days, and 139 ± 80 days. Mortality, culling, and retention rates for females from birth to first calving were 24, 27, and 49%. Lactation number, season of calving, and death of calf early in lactation had significant effects on milk yield. Repeatabilities of milk yield, lactation length, calving interval, dry period, and days open were .42, .19, .21, .03, and .23 with corresponding heritabilities .64, .19, .09, .19, and .27. Heritability for age of first calving was .84. Confounding by some environmental effects probably biased heritability estimates upward. Potential genetic improvement of milk yield by mass selection was estimated at .8% per year. Contemporary Jersey X Deshi crosses exceeded Deshi for milk yield, age of first calving, lactation length, calving interval, and days open by +923 kg, -15 months, +41, -84, and -96 days. At least one generation of crossing with European breeds is recommended over mass selection of Deshi

    Complexity-based learning and teaching: a case study in higher education

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    This paper presents a learning and teaching strategy based on complexity science and explores its impacts on a higher education game design course. The strategy aimed at generating conditions fostering individual and collective learning in educational complex adaptive systems, and led the design of the course through an iterative and adaptive process informed by evidence emerging from course dynamics. The data collected indicate that collaboration was initially challenging for students, but collective learning emerged as the course developed, positively affecting individual and team performance. Even though challenged, students felt highly motivated and enjoyed working on course activities. Their perception of progress and expertise were always high, and the academic performance was on average very good. The strategy fostered collaboration and allowed students and tutors to deal with complex situations requiring adaptation

    Measuring social desirability amongst men with intellectual disabilities: The psychometric properties of the Self- and Other-Deception Questionnaire—Intellectual Disabilities

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    Background Social desirability has been construed as either inaccurately attributing positive characteristics to oneself (self-deception), or inaccurately denying that one possesses undesirable characteristics to others (other-deception or impression management). These conceptualisations of social desirability have not been considered in relation to people with intellectual disabilities (IDs), but they are important constructs to consider when undertaking a psychological assessment of an individual, especially within forensic contexts. Therefore, we revised two existing measures of self- and other-deception and considered their psychometric properties. Methods Thirty-two men with mild IDs and 28 men without IDs completed the Self- and Other-Deception Questionnaires—Intellectual Disabilities (SDQ-ID and ODQ-ID) on two occasions, two weeks apart. Results Men with IDs scored significantly higher on the SDQ-ID and the ODQ-ID than men without IDs. However, these differences disappeared when Full Scale IQ, Verbal IQ and Performance IQ were controlled in relation to the SDQ-ID, and partially disappeared in relation to the ODQ-ID. The SDQ-ID and the ODQ-ID had substantial internal consistency in relation to men with IDs (k = 0.82 and 0.84 respectively). The test-retest reliability of the SDQ-ID was good (ri = 0.68), while the test-retest reliability of the ODQ-ID was moderate (ri = 0.56), for men with IDs. The SDQ-ID had moderate (k = 0.60) and the ODQ-ID had substantial (k = 0.70) internal consistency in relation to men without IDs, while the test-retest reliability of the SDQ-ID was excellent (ri = 0.87) as was the case for the ODQ-ID (ri = 0.85). Conclusions The SDQ-ID and the ODQ-ID have satisfactory psychometric properties in relation to men with and without IDs. Future research using these instruments is propose

    A longer vernal window: The role of winter coldness and snowpack in driving spring thresholds and lags

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    Climate change is altering the timing and duration of the vernal window, a period that marks the end of winter and the start of the growing season when rapid transitions in ecosystem energy, water, nutrient, and carbon dynamics take place. Research on this period typically captures only a portion of the ecosystem in transition and focuses largely on the dates by which the system wakes up. Previous work has not addressed lags between transitions that represent delays in energy, water, nutrient, and carbon flows. The objectives of this study were to establish the sequence of physical and biogeochemical transitions and lags during the vernal window period and to understand how climate change may alter them. We synthesized observations from a statewide sensor network in New Hampshire, USA, that concurrently monitored climate, snow, soils, and streams over a three-year period and supplemented these observations with climate reanalysis data, snow data assimilation model output, and satellite spectral data. We found that some of the transitions that occurred within the vernal window were sequential, with air temperatures warming prior to snow melt, which preceded forest canopy closure. Other transitions were simultaneous with one another and had zero-length lags, such as snowpack disappearance, rapid soil warming, and peak stream discharge. We modeled lags as a function of both winter coldness and snow depth, both of which are expected to decline with climate change. Warmer winters with less snow resulted in longer lags and a more protracted vernal window. This lengthening of individual lags and of the entire vernal window carries important consequences for the thermodynamics and biogeochemistry of ecosystems, both during the winter-to-spring transition and throughout the rest of the year

    Reproductive efficiency and viability in two \u3ci\u3eBos indicus \u3c/i\u3eand two \u3ci\u3eBos taurus \u3c/i\u3e breeds in the tropics of India and Colombia

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    Records from two herds in India and two in Columbia representing respectively two breeds of Bos indicus (Hariana and Deshi) and two Bos taurus breeds—Blanco Orejinegro (BON) and Costeño Con Cuernos (CCC) were evaluated for breeding efficiency and viability. Average age at first calving was 52.1, 46.3, 39.5 and 40.7 months for Hariana, Deshi, CCC and BON. Season of birth did not influence age at calving. Ranking for calving interval was similar, average 479, 418, 396 and 382 days with season effects significant (P\u3c.05) for only Deshi. BON and CCC had fewer days open but much shorter lactation periods, average 73 and 157, thus days carried calf in lactation were similar for all breeds. Percent of time dry per calving interval was high for all breeds, 44.2, 36.7, 64.1 and 81.0 for Hariana, Deshi, BON and CCC. Average annual mortality of females by 12 months of age was 23.6% for Hariana, 17.0% Deshi and 27.0% BON. In the same herds 46.4%, 51.1% and 49.0% of females born alive lived to first calving and annual losses among cows were 18.0%, 17.0%, and 21.0%; therefore, affording little opportunity for selection among females. Temperament, as determined by response to the milking process with and without the calf present, showed all the breeds were similar in this respect. Environmental effects were most important for all traits but genetic differences were indicated for age at first calving and milk yield. On a theoretical basis little gain could be expected in net dairy merit from crosses between the Columbian and Indian breeds

    Introduction: Examined Live – An Epistemological Exchange Between Philosophy and Cultural Psychology on Reflection

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    Besides the general agreement about the human capability of reflection, there is a large area of disagreement and debate about the nature and value of “reflective scrutiny” and the role of “second-order states” in everyday life. This problem has been discussed in a vast and heterogeneous literature about topics such as epistemic injustice, epistemic norms, agency, understanding, meta-cognition etc. However, there is not yet any extensive and interdisciplinary work, specifically focused on the topic of the epistemic value of reflection. This volume is one of the first attempts aimed at providing an innovative contribution, an exchange between philosophy, epistemology and psychology about the place and value of reflection in everyday life. Our goal in the next sections is not to offer an exhaustive overview of recent work on epistemic reflection, nor to mimic all of the contributions made by the chapters in this volume. We will try to highlight some topics that have motivated a new resumption of this field and, with that, drawing on chapters from this volume where relevant. Two elements defined the scope and content of this volume, on the one hand, the crucial contribution of Ernest Sosa, whose works provide original and thought-provoking contributions to contemporary epistemology in setting a new direction for old dilemmas about the nature and value of knowledge, giving a central place to reflection. On the other hand, the recent developments of cultural psychology, in the version of the “Aalborg approach”, reconsider the object and scope of psychological sciences, stressing that “[h]uman conduct is purposeful”

    Discreet element modeling of under sleeper pads using a box test

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    It has recently been reported that under sleeper pads (USPs) could improve ballasted rail track by decreasing the sleeper settlement and reducing particle breakage. In order to find out what happens at the particle-pad interface, discrete element modelling (DEM) is used to provide micro mechanical insight. The same positive effects of USP are found in the DEM simulations. The evidence provided by DEM shows that application of a USP allows more particles to be in contact with the pad, and causes these particles to transfer a larger lateral load to the adjacent ballast but a smaller vertical load beneath the sleeper. This could be used to explain why the USP helps to reduce the track settlement. In terms of particle breakage, it is found that most breakage occurs at the particle-sleeper interface and along the main contact force chains between particles under the sleeper. The use of USPs could effectively reduce particle abrasion that occurs in both of these regions

    Natural history of Arabidopsis thaliana and oomycete symbioses

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    Molecular ecology of plant–microbe interactions has immediate significance for filling a gap in knowledge between the laboratory discipline of molecular biology and the largely theoretical discipline of evolutionary ecology. Somewhere in between lies conservation biology, aimed at protection of habitats and the diversity of species housed within them. A seemingly insignificant wildflower called Arabidopsis thaliana has an important contribution to make in this endeavour. It has already transformed botanical research with deepening understanding of molecular processes within the species and across the Plant Kingdom; and has begun to revolutionize plant breeding by providing an invaluable catalogue of gene sequences that can be used to design the most precise molecular markers attainable for marker-assisted selection of valued traits. This review describes how A. thaliana and two of its natural biotrophic parasites could be seminal as a model for exploring the biogeography and molecular ecology of plant–microbe interactions, and specifically, for testing hypotheses proposed from the geographic mosaic theory of co-evolution
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