433 research outputs found

    Tree Biomass and Carbon Storage in an Old Growth Forest in Southeastern Ohio

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    Recently there has been increased interest in determining the baseline levels of carbon storage in different ecosystems, because of greater concern over the issue of global climate change and increased atmospheric CO2 concentrations. With a better understanding of carbon sequestration in various ecosystems, we can use land in a more environment-conscious way, and negative human impacts on the earth can be decreased. Forest ecosystems are especially important, because they have an immense capacity to store carbon as compared to other ecosystems. The majority of carbon sequestered in forest ecosystems is contained in tree biomass, but there is also carbon contained in soil, leaf litter, and necromass. The primary objective of our experiment was to determine and compare the baseline amount of carbon sequestered in the biomass of different forest plots: old-growth versus young-growth and north-facing versus south-facing. We also compared these results to data that had been collected from the same plots in 2003. We found that for the most part, the amount of biomass had decreased; the only exception was the north-facing young-growth stand. This forest plot contained the most biomass, followed by the old-growth south-facing, then the young-growth south-facing, then the old-growth north-facing. We believe that the reason for the overall decrease in biomass was a large number of fallen trees

    Moving forward in circles: challenges and opportunities in modelling population cycles

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    Population cycling is a widespread phenomenon, observed across a multitude of taxa in both laboratory and natural conditions. Historically, the theory associated with population cycles was tightly linked to pairwise consumer–resource interactions and studied via deterministic models, but current empirical and theoretical research reveals a much richer basis for ecological cycles. Stochasticity and seasonality can modulate or create cyclic behaviour in non-intuitive ways, the high-dimensionality in ecological systems can profoundly influence cycling, and so can demographic structure and eco-evolutionary dynamics. An inclusive theory for population cycles, ranging from ecosystem-level to demographic modelling, grounded in observational or experimental data, is therefore necessary to better understand observed cyclical patterns. In turn, by gaining better insight into the drivers of population cycles, we can begin to understand the causes of cycle gain and loss, how biodiversity interacts with population cycling, and how to effectively manage wildly fluctuating populations, all of which are growing domains of ecological research

    PENGEMBANGAN BISKUIT MP-ASI DENGAN PENAMBAHAN PUREE LABU KUNING (Cucurbita moschata) DAN TEPUNG BERAS MERAH (Oryza nivara)

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    Makanan pendamping air susu ibu (MP-ASI) merupakan makanan pendamping dari air susu ibu yang disiapkan untuk membantu memenuhi kebutuhan gizi bayi. MP-ASI diberikan kepada bayi ketika air susu ibu sudah tidak cukup dalam memenuhi kebutuhan gizi anak. Pada bayi usia 12-24 bulan mulai diperkenalkan dengan jenis makanan padat seperti biskuit sebagai MP-ASI. Biskuit MP-ASI dapat dikembangkan melalui pemanfaatan bahan pangan lokal seperti labu kuning yang memiliki kandungan beta karoten dan tepung beras merah yang memiliki kandungan protein. Puree labu kuning merupakan bentuk produk olahan dari buah labu kuning dengan pemberian proses pengukusan. Tepung beras merah merupakan bentuk produk olahan dari beras merah. Penelitian ini bertujuan untuk mendapatkan biskuit MP-ASI yang mampu memberikan kandungan gizi terbaik seperti vitamin A dan protein, untuk mengetahui pengaruh penambahan puree labu kuning dan tepung beras merah pada biskuit MP-ASI, selain itu juga mengetahui tingkat kesukaan pada masing-masing formulasi biskuit. Pada penelitian ini menggunakan 4 formulasi biskuit MP-ASI, yaitu biskuit kontrol tanpa penambahan puree labu kuning dan tepung beras merah, biskuit formulasi 1 dengan penambahan 5% tepung beras merah dan 10% puree labu kuning, biskuit formulasi 2 dengan penambahan 7,5% tepung beras merah dan 7,5% puree labu kuning, serta biskuit formulasi 3 dengan penambahan 10% tepung beras merah dan 5% puree labu kuning. Analisa yang dilakukan dalam penelitian ini adalah analisa fisik, analisa kimiawi, dan analisa organoleptik. Pada analisa fisik warna yang terbaik dimiliki biskuit kontrol dan analisa tekstur terkeras dimiliki biskuit formulasi 3 dan formulasi terlunak dimiliki biskuit formulasi 1 dengan penambahan puree labu kuning terbanyak. Analisa kimiawi yang dilakukan menghasilkan biskuit formulasi 3 memiliki kadar abu tertinggi yaitu 1,63%, kadar protein tertinggi yaitu 6,16%. Kadar air tertinggi dimiliki biskuit formulasi 1 yaitu 4,80%, kadar lemak teringgi dimiliki biskuit kontrol sebesar 37,59%, dan kadar karbohidrat tertinggi dimiliki biskuit formulasi 2 yaitu sebesar 56,61%. Kadar beta karoten tertinggi dimiliki biskuit formulasi 1 yaitu sebesar 4,32 mg/100 gram produk. Hasil analisa organoleptik biskuit MP-ASI kontrol memiliki tingkat kesukaan overall tertinggi dengan rata-rata 2,88. Selain itu biskuit formulasi 1 merupakan formulasi yang agak disukai disukai panelis dengan rata-rata 2,65 dengan penambahan 10% puree labu kuning dan 5% tepung beras merah

    Factors affecting consistency and accuracy in identifying modern macroperforate planktonic foraminifera

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    Planktonic foraminifera are widely used in biostratigraphic, palaeoceanographic and evolutionary studies, but the strength of many study conclusions could be weakened if taxonomic identifications are not reproducible by different workers. In this study, to assess the relative importance of a range of possible reasons for among-worker disagreement in identification, 100 specimens of 26 species of macroperforate planktonic foraminifera were selected from a core-top site in the subtropical Pacific Ocean. Twenty-three scientists at different career stages – including some with only a few days experience of planktonic foraminifera – were asked to identify each specimen to species level, and to indicate their confidence in each identification. The participants were provided with a species list and had access to additional reference materials. We use generalised linear mixed-effects models to test the relevance of three sets of factors in identification accuracy: participant-level characteristics (including experience), species-level characteristics (including a participant’s knowledge of the species) and specimen-level characteristics (size, confidence in identification). The 19 less experienced scientists achieve a median accuracy of 57 %, which rises to 75 % for specimens they are confident in. For the 4 most experienced participants, overall accuracy is 79 %, rising to 93 % when they are confident. To obtain maximum comparability and ease of analysis, everyone used a standard microscope with only 35× magnification, and each specimen was studied in isolation. Consequently, these data provide a lower limit for an estimate of consistency. Importantly, participants could largely predict whether their identifications were correct or incorrect: their own assessments of specimen-level confidence and of their previous knowledge of species concepts were the strongest predictors of accuracy

    X-ray, Optical, and Radio Observations of the Type II Supernovae 1999em and 1998S

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    Observations of the Type II-P (plateau) Supernova (SN) 1999em and Type IIn (narrow emission line) SN 1998S have enabled estimation of the profile of the SN ejecta, the structure of the circumstellar medium (CSM) established by the pre-SN stellar wind, and the nature of the shock interaction. SN 1999em is the first Type II-P detected at both X-ray and radio wavelengths. The Chandra X-ray data indicate non-radiative interaction of SN ejecta with a power-law density profile (rho \propto r^{-n} with n ~ 7) with a pre-SN wind with a low mass-loss rate of ~2 \times 10^{-6} M_sun/yr for a wind velocity of 10 km/sec, in agreement with radio mass-loss rate estimates. The Chandra data show an unexpected, temporary rise in the 0.4--2.0 keV X-ray flux at ~100 days after explosion. SN 1998S, at an age of >3 years, is still bright in X-rays and is increasing in flux density at cm radio wavelengths. Spectral fits to the Chandra data show that many heavy elements (Ne, Al, Si, S, Ar, and Fe) are overabundant with respect to solar values. We compare the observed elemental abundances and abundance ratios to theoretical calculations and find that our data are consistent with a progenitor mass of approximately 15-20 M_sun if the heavy element ejecta are radially mixed out to a high velocity. If the X-ray emission is from the reverse shock wave region, the supernova density profile must be moderately flat at a velocity ~10^4 km/sec, the shock front is non-radiative at the time of the observations, and the mass-loss rate is 1-2 \times 10^{-4} M_sun/yr for a pre-supernova wind velocity of 10 km/sec. This result is also supported by modeling of the radio emission which implies that SN 1998S is surrounded by a clumpy or filamentary CSM established by a high mass-loss rate, ~2 \times 10^{-4} M_sun/yr, from the pre-supernova star.Comment: 14 pages, 10 figures, accepted by ApJ, includes new data (one new obs. each of SN 1999em and SN 1998S), expanded discussion of spectral fit

    Phenotypic plasticity in normal breast derived epithelial cells

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    Background Normal, healthy human breast tissue from a variety of volunteer donors has become available for research thanks to the establishment of the Susan G. Komen for the Cure® Tissue Bank at the IU Simon Cancer Center (KTB). Multiple epithelial (K-HME) and stromal cells (K-HMS) were established from the donated tissue. Explant culture was utilized to isolate the cells from pieces of breast tissue. Selective media and trypsinization were employed to select either epithelial cells or stromal cells. The primary, non-transformed epithelial cells, the focus of this study, were characterized by immunohistochemistry, flow cytometry, and in vitro cell culture. Results All of the primary, non-transformed epithelial cells tested have the ability to differentiate in vitro into a variety of cell types when plated in or on biologic matrices. Cells identified include stratified squamous epithelial, osteoclasts, chondrocytes, adipocytes, neural progenitors/neurons, immature muscle and melanocytes. The cells also express markers of embryonic stem cells. Conclusions The cell culture conditions employed select an epithelial cell that is pluri/multipotent. The plasticity of the epithelial cells developed mimics that seen in metaplastic carcinoma of the breast (MCB), a subtype of triple negative breast cancer; and may provide clues to the origin of this particularly aggressive type of breast cancer. The KTB is a unique biorepository, and the normal breast epithelial cells isolated from donated tissue have significant potential as new research tools

    Ghrelin receptor antagonist JMV2959 blunts cocaine and oxycodone drug-seeking, but not self-administration, in male rats

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    The drug overdose crisis has spawned serious health consequences, including the increased incidence of substance use disorders (SUDs), conditions manifested by escalating medical and psychological impairments. While medication management is a key adjunct in SUD treatment, this crisis has crystallized the need to develop additional therapeutics to facilitate extended recovery from SUDs. The “hunger hormone” ghrelin acts by binding to the growth hormone secretagogue receptor 1α (GHS1αR) to control homeostatic and hedonic aspects of food intake and has been implicated in the mechanisms underlying SUDs. Preclinical studies indicate that GHS1αR antagonists and inverse agonists suppress reward-related signaling associated with cocaine and opioids. In the present study, we found that the GHS1αR antagonist JMV2959 was efficacious to suppress both cue-reinforced cocaine and oxycodone drug-seeking, but not cocaine or oxycodone self-administration in male Sprague-Dawley rats. These data suggest a role of the ghrelin-GHS1αR axis in mediating overlapping reward-related aspects of cocaine and oxycodone and premises the possibility that a GHS1αR antagonist may be a valuable therapeutic strategy for relapse vulnerability in SUDs

    Race Yourselves: A Longitudinal Exploration of Self-Competition Between Past, Present, and Future Performances in a VR Exergame

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    Participating in competitive races can be a thrilling experience for athletes, involving a rush of excitement and sensations of flow, achievement, and self-fulfilment. However, for non-athletes, the prospect of competition is often a scary one which affects intrinsic motivation negatively, especially for less fit, less competitive individuals. We propose a novel method making the positive racing experience accessible to non-athletes using a high-intensity cycling VR exergame: by recording and replaying all their previous gameplay sessions simultaneously, including a projected future performance, players can race against a crowd of "ghost" avatars representing their individual fitness journey. The experience stays relevant and exciting as every race adds a new competitor. A longitudinal study over four weeks and a cross-sectional study found that the new method improves physical performance, intrinsic motivation, and flow compared to a non-competitive exergame. Additionally, the longitudinal study provides insights into the longer-term effects of VR exergames

    Exceptional freshening and cooling in the eastern subpolar North Atlantic caused by reduced Labrador Sea surface heat loss

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    Observations of the eastern subpolar North Atlantic in the 2010s show exceptional freshening and cooling of the upper ocean, peaking in 2016 with the lowest salinities recorded for 120 years. Published theories for the mechanisms driving the freshening include: reduced transport of saltier, warmer surface waters northwards from the subtropics associated with reduced meridional overturning; shifts in the pathways of fresher, cooler surface water from the Labrador Sea driven by changing patterns of wind stress; and the eastward expansion of the subpolar gyre. Using output from a high-resolution hindcast model simulation, we propose that the primary cause of the exceptional freshening and cooling is reduced surface heat loss in the Labrador Sea. Tracking virtual fluid particles in the model backwards from the eastern subpolar North Atlantic between 1990 and 2020 shows the major cause of the freshening and cooling to be an increased outflow of relatively fresh and cold surface waters from the Labrador Sea; with a minor contribution from reduced transport of warmer, saltier surface water northward from the subtropics. The cooling, but not the freshening, produced by these changing proportions of waters of subpolar and subtropical origin is mitigated by reduced along-track heat loss to the atmosphere in the North Atlantic Current. We analyse modelled boundary exchanges and water mass transformation in the Labrador Sea to show that since 2000, while inflows of lighter surface waters remain steady, the increasing output of these waters is due to reduced surface heat loss in the Labrador Sea beginning in the early 2000s. Tracking particles further upstream reveals that the primary source of the increased volume of lighter water transported out of the Labrador Sea is increased recirculation of water, and therefore longer residence times, in the upper 500–1000 m of the subpolar gyre
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